Accepted projects

Land use impact on soil quality using soil arthropods in the Negev (QBSN)

ExpeER TA Site: Negev, ISRAEL
TA User (visit): Cristina Menta, Dept. of Life Sciences, Parma University, Italy (March, 2015 – 06 days)
Project Description: We propose an efficient and low-cost biological index of soil quality: QBS-ar index (acronym of soil biological quality, in Italian “Qualità Biologica del Suolo”). This index is a biological method that joins the biodiversity of soil microarthropods community with the degree of soil animal vulnerability. It is based on the following concept: the higher is the soil quality, the higher is the number of microarthropod groups morphologically well adapted to soil. This protocol, through the study of the soil microarthropods, provides information on the soil biological quality, which is an indicator of land degradation. QBS-ar has been developed by an Italian team (Parisi et al, 2005) more than ten years ago, and it has been applied by Italian and European specialists in several ecosystems, agricultural lands, grasslands, urban soils, woods at different level of naturality, and degraded soils (Galli et al., 2014; Hartley et al. 2008; Menta et al., 2008, 2011, 2014). It has been adopted by WP2 of ExpeER as the protocol to study soil fauna.
The study is intended for the assessment of the soil mesofauna present in a studied site using a simple index which doesn’t involve species identification skills. Soil samples will be collected in 5 sites of the Negev LTER, soil microarthropods will be extracted by a dynamic extraction method (Berlese-Tüllgren funnel) in laboratory and successively identified at the level of Recognizable Taxonomic Unit (RTU). Each RTU receives a score ranging from 1 to 20, according to its adaptation degree to soil, following a score grid. The final index sums up these scores to the QBS-ar index of soil health. This study will compare 5 sites of the Negev LTER and evaluate the effects of the land use on the soil quality. We will also compare these results to the scores obtained in several sites already studied of the colder Europe. We will also develop a modified version of the QBS-ar index that include the abundance data, similarly to Rubenstein (2012) weighted index.

Distribution of soil organic matter in deep soil layers under maize cultivation (DEEPSOM)

ExpeER TA Site: Tetto Frati, ITALY
TA User (visit): Taru Lehtinen, Austrian Agency for Health and Food Safety, Austria (March, 2015 – 05 days)
Project Description: Deep soil organic matter (SOM) and microbial activity in the deeper soil layers is a topic not often covered in agricultural studies since the main interest lies within the most active topsoils and deep soils are more time consuming to sample. However, studies have shown that deep SOM does matter (Harper and Tibbet, 2013), although its function and dynamics are not fully understood yet (Rumpel and Kögel- Knabner, 2011). Deep SOM originates mainly from dissolved organic carbon, root products, and transported particulates from the soil surface (Rumpel and Kögel-Knabner, 2011). Subsoils can contribute up to more than half of the total soil C stocks, as was recently confirmed in England and Wales (Gregory et al., 2014), thus, their role, e.g. in C sequestration, should not be underestimated (Rumpel and Kögel-Knabner, 2011). Organo-mineral interactions may play a major role in SOM stabilization, as was shown in calcareous soils from Germany (Grünewald et al., 2006). It has been shown that the molecular structure alone does not determine the stability of SOM, but physical connections and disconnection between microorganisms and SOM control how much is stabilized in the soil (Schmidt et al., 2011). .
In this study, the main aim is to investigate the soil organic matter dynamics in the first meter of the soil profiles in the long-term maize cropping system experiment Tetto Frati, in the vicinity of the Po river in Northern Italy. In addition, soil aggregate stability will be investigated. The detailed objectives of this study are: - Can soil management induced differences that have been detected in the topsoils also be detected in the deeper soil layers? - How are the active carbon, total organic carbon, total nitrogen and potentially mineralizable N distributed in the soil profiles? - How is soil respiration affected by the soil depth? - How is aggregate stability affected by the soil depth? - How are carbon and nitrogen distributed in the micro- (<250μm) and macroaggregates (>250μm)?

Mapping forest background reflectance in an arid region using multi-angle remote sensing data

ExpeER TA Site: Negev, ISRAEL
TA User (visit): Jan Pisek, Tartu Observatory, Toravere, Estonia (March, 2015 – 05 days)
Project Description: Since ground layer (understory or background) has an essential contribution to the whole-stand reflectance signal in many forests, its reflectance spectra are urgently needed in various forest reflectance modelling efforts. However, systematic reflectance data covering different site types are almost missing. Measurement of background reflectance is a real challenge because of extremely high variability of irradiance at the forest floor, weak signal in some parts of the spectrum and its variable nature. Forest background might consist of several sub-layers (tree regeneration, shrub, grasses or dwarf shrub, mosses or lichens, litter, bare soil), it has spatially-temporally variable species composition and ground coverage. Additional problems are introduced by patchiness of ground vegetation, ground surface roughness and understory-overstory relations. Due to this variability, remote sensing might be the only technology to provide consistent data at the required spatially extensive scales. The objective of this project is to collect in situ measured background reflectance data in Yatir Forest, Israel. The obtained in situ measurements will be used for the validation and comparison with the background reflectance retrievals over the same area (Yatir Forest) using MODIS BRDF data and methodology outlined in Pisek et al. (2012, 2015). The methodology was originally developed for the forest background signal retrieval in a boreal region. Here its performance will be tested in arid forest conditions, which is a necessary step before conducting global-scale mapping over forested areas. The results can be also used as an input for improved modeling of local carbon and energy fluxes.

Investigating the impacts of deforestation on hydrological and sediment connectivity in the Wüstebach catchment, Germany (LACOCON)

ExpeER TA Site: TERENO (ITS1, Jülich, GERMANY)
TA User (visit): Ronald Poppl, University of Vienna, Austria (March, 2015 – 05 days)
Project Description: Knowledge on sediment dynamics is fundamental to the understanding of geomorphic and ecologic systems as geomorphic processes can for instance erode valuable soil layers. Entering the fluvial system the transported matter can modify channel morphology and thus influence flow dynamics, habitat evolution and element concentration, or even govern the fate of sediment-associated detrimental pollutants. To current knowledge, those earth surface shaping processes are strongly influenced by climate, underlying lithology, vegetation and human impact (Syvitsky & Milliman 2007). However, we are lacking basic concepts and methodological approaches to untangle the complexity inherent in hydro-geomorphic systems which are related to interactions and feedback processes between landscape compartments and processes involved.
Recently, the role of connectivity in controlling runoff and erosion has received significant and increasing scientific attention (e.g. Parsons et al. 2015, in press). Related to sediment dynamics, sediment connectivity is defined by Hooke (2003, p. 79) as “the potential for a specific [sediment] particle to move through the system”. Connectivity concepts and assessments are increasingly used to describe linkages between sediment source areas and the corresponding sinks within a catchment (Croke et al. 2005) and are therefore an important tool to estimate sediment conveyance and propagation through a system (e.g. Poeppl et al. 2012). Investigating sediment connectivity in geomorphic systems provides an important opportunity to improve our understanding of how physical linkages govern geomorphic processes (Van Oost et al. 2000; Wainwright et al. 2011) and geomorphic responses to change. Given that the sensitivity of a system to change is largely governed by the capacity of its various components to transmit an impulse, an effective assessment of connectivity between these components provides a basis to identify transmission linkages, coupling efficiencies and thus sensitive elements within the system (Brunsden 2001, Brierley et al. 2006).
The main aim of the proposed project is to investigate the impacts of deforestation on hydrological and sediment connectivity in the Wuestebach catchment. Research questions: a) How does deforestation influence hydrological connectivity, sediment pathways and fluxes in the Wuestebach catchment? b) Is gross sediment transport governed by high-magnitude meteorological events, or are small magnitudes equally important? c) How does deforestation influence the river runoff regime and channel morphology? d) How does geomorphic catchment evolution evolve in future?

Climate Change impact on tree growth (CC-Imp)

ExpeER TA Site: Hesse, FRANCE; Achenkirch, AUSTRIA; Klausenleopoldsdorf, AUSTRIA; Zöbelboden, AUSTRIA; Hoglwald Forest, GERMANY; Eifel, GERMANY
TA User (visit): Pierluigi Bombi, CNR-IBAF, Italy (March, 2015 – 05 days)
Project Description: Recent Climate Change is recognized as one of the main threat to natural ecosystems (Walther et al., 2002; Parmesan and Yohe, 2003; Root et al., 2003). Climate Change influences several aspects of species biology, such as physiology (e.g. Valentini et al., 2000), phenology (e.g. Peñuelas and Filella, 2001), and distribution (e.g. Kelly and Goulden, 2008). Species range shifts are due to changes in habitat suitability across space, which drive species to move towards those areas where climate continue to fulfill the species niche (Wiens et al., 2009). Species distribution models are often used for predicting future range shifts under climate change scenarios and adapting conservation strategies (Guisan and Zimmermann, 2000).
Nevertheless, the validation of species distribution models is difficult in dynamic scenarios and their real applicability is still debated (e.g. Araújo et al., 2005). In addition, in order to plan effective measures of impact mitigation, an instrument for detecting the real effects of climate change on natural ecosystem is required. We hypothesize that the spatial pattern of dynamic response (as tree growth) to climate change can allow to disentangle multiple effects of different drivers (e.g. habitat alteration, pollution, climate change), providing a key for validating models and monitoring ecosystem dynamics. In particular, in sites close to the front border of a shifting range, the environmental conditions are becoming more suitable than in the past. Therefore, we expect that in these sites tree growth has speeded up during the last years. On the contrary, in sites close to the rear border, the environment is less suitable than in the past and we can expect that tree growth has slowed down during the last years. Similarly, sites far from both front and rear borders are as suitable as in the past and we can expect that tree growth is rather constant. The detection of this spatial pattern of growth trends can confirm the model outcomes and highlight the occurring impact.
The aim of this project is to test our hypothesis and to set up a method for identifying climate change effect on forest ecosystems. To do this, we will use three species (i.e. Abies alba, Picea abies, and Fagus sylvatica) with different distributions and environmental requirements. On the basis of their current distributions, we will predict their range shifts due to climate change and we will verify whether their growth is following our expected spatial pattern. If we will find the expected pattern of growth for the three species, we will obtain at the same time a strong field-based validation for our models and a ring of alarm for European forests impacted by climate change.

Development of a regional hydrological and biogeochemical model

ExpeER TA Site: Zöbelboden, AUSTRIA
TA User (visit): Andreas Hartmann, University of Freiburg, Institute for Geo- and Environmental Natural Sciences, Germany (March, 2015 – 05 days)
Project Description: In past studies at the LTER Zöbelboden, Dr Hartmann and the local team of researchers developed and applied simulation tools to simulate and predict the hydrological and biogeochemical behvior of the test site (Hartmann et al., 2010, 2012, 2015). As it is regarded to be representative for its region (National Park “Kalkalpen”) it is now time upscale the information gained from the long-term monitoring at the LTER Zöbelboden site to apply the model on a regional scale, which is crucial for understanding the measured impact on larger scales. Regional simulations and predictions of water availability and its quality will facilitate the present and future water and ecosystem management of this valuable nature reserve.

Prior Spectral Knowledge for Ecosystem Service Monitoring and Understanding (PriorSpecK4ECOS)

ExpeER TA Site: Negev, ISRAEL
TA User (visit): Andrea Baraldi , Università degli Studi di Napoli Federico II, Italy (February / March, 2015 – 90 days)
Project Description: Although rarely acknowledged by the remote sensing (RS) community, prior knowledge-based preliminary classification (pre-classification) of multi-spectral (MS) imagery, suitable for driven-by-knowledge continuous color space discretization (quantization, partitioning), has a long history. Equivalent to color naming in a natural language, it is the deductive counterpart of popular inductive data learning algorithms for vector data quantization, like the k-means algorithm. In recent years, the presentation of the prior knowledge-based Satellite Image Automatic Mapper (SIAM) and RGB-SIAM color quantizers in operating mode has brought new developments in the design and implementation of hybrid inference-based (combined deductive/top-down and inductive/bottom-up) remote sensing (RS) image understanding systems (RS-IUSs). The SIAM/ RGB-SIAM expert systems are capable of generating, alternately automatically and in near real-time, multi-level pre-classification maps and multi-scale segmentation maps of a multi-source (e.g., spaceborne/airborne) multi-resolution MS image, either radiometrically calibrated (into top-of-atmosphere reflectance, surface reflectance or surface albedo values) or radiometrically uncalibrated, respectively. The goal of the present research and technological development project proposal is to employ the novel SIAM/RGB-SIAM pre-attentive vision technology to improve, in terms of quantitative metrological/ statistically-based quality indexes of operativeness (QIOs, encompassing degree of automation, accuracy, efficiency, robustness, scalability, timeliness and costs), any pre-existing ecological processing model whose input land surface variables, either categorical (e.g., land cover (LC) classes) or continuous (e.g., leaf area index), are estimated from RS imagery. To reach this overarching goal, specific research topics are gathered into three main categories (I) to (III), namely: (I) Sensory data. Automatic driven-by-knowledge stratified data pre-preprocessing, e.g., MS image mosaicking, co-registration, compositing, topographic correction, surface albedo estimation, etc. (II) Categorical variables. Automatic multi-sensor multi-resolution LC/LC change (LCC) detection in single-date/multi-temporal MS/hyperspectral imagery, e.g., rain fed afforestation, runoff harvesting afforestation, managed/unmanaged grazing, etc. (III) Continuous variables. Spectral prior knowledge-based stratification of statistical/semi-empirical ecosystem processing models, e.g., development and validation of innovative all-channel combined categorical/continuous spectral variables (e.g., greenness index).

Methane (CH₄) and nitrous oxide (N₂O) fluxes from boreal tree species (MENOFLUX)

ExpeER TA Site: Hyytiala, FINLAND
TA User (visit): Katerina Machacova, Global Change Research Centre, Academy of Sciences of the Czech Republic (February / March, 2015 – 16 days)
Project Description: Boreal upland forests have been considered to be an important natural sink of CH₄ and a natural source of N₂O. However, measurement campaigns in boreal upland forest in Hyytiala, Southern Finland, showed for the first time that Scots pine (Pinus sylvestris), European spruce (Picea abies), and silver birch (Betula pendula), as typical boreal tree representatives, can emit both N₂O and CH₄, and can significantly contribute to the N₂O and CH₄ exchange of the boreal forest (Machacova et al. 2013a, 2014). However, the question is whether all three tree species emit N₂O and CH₄ all year long.
Therefore, the proposed project will continue the successful measurement campaigns in 2013 and 2014 to study the seasonal changes of tree CH₄ and N₂O flux rates. The main objective will be to characterize and quantify the CH₄ and N₂O fluxes from stems of P. sylvestris, P. abies and B. pendula in winter. We assume that the CH₄ and N₂O fluxes from stems will be significantly reduced due to decreased transpiration. This hypothesis is based on the assumption of a transpiration stream as a pathway for N₂O and CH₄ (Macháčová 2013b). The gas fluxes will be investigated on mature trees under natural field conditions using stem chamber systems and subsequent gas chromatographic analyses of emitted trace gases. Forest floor fluxes of CH₄ and N₂O will be determined parallel to stem fluxes to enable their comparison. Continuously measured micro-climatic data will be used for correlation analyses to investigate their effects on tree fluxes of N₂O and CH₄.

C and N dynamics in an amended soil-plant system (AMENISOT)

ExpeER TA Site: Grignon, FRANCE
TA User (visit): Maria Angeles Bustamante Munoz, Department of Agrochemistry and Environment, Miguel Hernandez University, Spain (February / March, 2015 – 15 days)
Project Description: The intensification of the livestock production systems has produced an increase in the production of manures and slurries, which must be properly managed to avoid a potential environmental impact. Composting is not a new technology, but it is being increasingly considered as an alternative to the disposal of this type of waste, obtaining a stabilised and humified material that can be used in agriculture and/or soil restoration. The effects of compost addition to soil are mainly associated to the nature and dynamics of its constituent organic matter. However, it is difficult to quantify the changes in organic matter during composting and the subsequent compost effects on soil organic matter. The natural abundance stable isotope 13C and 15N (or δ13C and δ15N) tracer technique can be used to characterise the dynamics of ‘native’ and ‘new’ soil organic C and N (Lynch et al., 2006). Isotope fractionation during composting may produce organic materials with a more homogenous δ13C and δ15N signature, which can allow the study of their fate in soil (Lynch et al., 2006). However, relatively few studies (Högberg, 1997; Bol et al., 2000, 2004; Glaser et al., 2001) have applied this technique to improve the knowledge about the transformation, utilisation and stabilisation of amendment C and N in soil, while the effect of composting on the δ13C and δ15N signature of manures and waste materials remains unexamined. In addition, as the natural abundance of the stable isotope 15N is considered as an integrator of N cycle processes (Högberg, 1997; Robinson, 2001), it has been applied extensively to provide information on the dynamics of N in soil–plant system (Högberg, 1997). For example, variations in 15N values of leaves or whole parts of plants have often been thought to reflect the sources of N used by plants. Since manure and compost are more enriched in 15N than inorganic fertiliser due to ammonia volatilisation, thereby leaving the residual N enriched in 15N (Kerley and Jarvis, 1996), crop and soil amended with manure or compost may show higher 15N than those treated with inorganic fertiliser (Yoneyama et al., 1990).
Therefore, we aim to evaluate the efficiency of the δ13C and δ15N tracer technique to study the effect of composting on the δ13C and δ15N signature of two livestock derived wastes, as well as the variations in the natural 13C and 15N abundances of soil and rosemary plants after the application of these composts. This research proposal is integrated within a research project to evaluate the efficiency of the use of organic amendments as a method of recovering and protecting Mediterranean areas prone to degradation. The research project was based on the study of the effects of the incorporation into a semiarid soil from central Italy of two composts elaborated using the solid fraction of two digestates (obtained after the anaerobic digestion of cattle and pig slurry, respectively) at different rates (30 t/ha and 60 t/ha), compared with a control treatment (the unamended soil) and a mineral fertilised soil. Additionally, in these soils, rosemary (Rosmarinus officinalis) plants were planted.
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Gradient measurements of NO concentration in soil pore space (GraMeNO)

ExpeER TA Site: Höglwald Forest, GERMANY
TA User (visit): Ute Skiba, Natural Environment Research Council, Centre for Ecology and Hydrology - CEH Edinburgh, UK (February / March, 2015 – 40 days)
Project Description: Recently we have completed two TA projects investigating the importance of soil NO emissions during cold time periods and its contribution to the annual budget. The “Wintertime emission of Nitric Oxide from Soil (WTENOS, P64)” project provided evidence of regularly occurring winter NO emissions with some large emission peaks, confirming previous reported data by Laville et al. (2011) and Yao et al., (2010). The contribution of cold time NO emissions was significant and contributed ca. 29% to the annual NO emission budget for Höglwald forest during the period 1994-2010. In the second TA project “Relationships between soil N₂O and NO Emission under Freeze-Thaw Events (REFTE; P77)” we have demonstrated strong positive relationships between NO and N₂O during freeze-thaw events. Moreover we have indicated steady correlation of both gases (NO and N₂O) with CO₂ fluxes, which suggests a heterotrophic origin of both N-gases. However, occasionally there were strict time delays of thawing induced NO emission peaks occurring ca. 2 days after the N₂O peak, usually following periods a prolonged subzero temperatures. The processes for this delay may be of physical rather than biochemical nature, due to a gradual accumulation of N₂O during the frozen period, where most of produced NO was trapped and converted into N₂O underneath the ice film (Maljanen et al., 2009; Jefferies et al., 2010; Yanai et al., 2011). The data showed that during melt all accumulated N₂O was rapidly released and both gases could be production and released (without ice obstacle) driven mainly by temperature and soil moisture. The data demonstrated that the soil moisture content in the appropriate layers could have negative effects on NO emission under very wet conditions. Also atmospheric pressure may be important in soil gas release to the atmosphere. Despite the progress we achieved in the WTENOS and REFTE TAs we still have no direct data of NO concentrations in the soil pore space at different depths neither during the cold nor the rest of the year to explain emission rates. It is widely reported that the top few cm of a soil are responsible for NO emissions (e.g., Ludwig et al., 2001; Schreiber et al., 2012; Pilegaard, 2013; Medinets et al., 2015) and those emissions seem to be cumulative originated by various processes (Medinets et al., 2015). However the answer to a seemingly simple question “why is only shallow soil layer responsible for NO emissions?” has not yet been answered. Possible causes could be related to 1) a NO concentration gradient at the soil atmosphere interface; 2) easier NO release from surface than deeper soil layers, 3) O₂ concentration dependence, 4) favorable conditions for biochemical processes, 5) cumulative effect of several/all listed factors.
To address the above points we will develop a high resolution system for in situ soil gradient NO concentration measurements and apply it at Höglwald Forest. The main objective is to develop and install an in situ high resolution system for gradient NO concentration monitoring; study the levels of NO concentrations in soil pore spaces at different depths during the cold periods in winter/early spring. In addition the main abiotic parameters, such as soil temperature and soil moisture will be measured in each layer. We are considering the possibility to monitor O₂ concentration in the soil pore space air, provided the equipment can be made available. The date will determine which soil layers are responsible for NO production and consumption. Knowledge of the O₂ and moisture levels would indicate the dominant microbial processes responsible for NO production within each layer. These data are important for model development and refinement, such as Landscape DNDC. The data generated in this TA project are novel and will result in a publication to be submitted to a high impact journal.

Long-term drought manipulation effects on tree biochemistry (ChemisTree)

ExpeER TA Site: Puechabon, FRANCE
TA User (visit): Jesus Rodriguez-Calcerrada, School of Forest Engineering, Technical University of Madrid, Spain (February, 2015 – 05 days)
Project Description: Precipitation manipulation experiments are an effective way to assess drought impact on tree and ecosystem functions while minimizing confounding factors. Current researches on tree acclimation to drought using such experiments have mostly focused on structural (e.g. Martin-StPaul et al. 2013) and functional changes (e.g. Rodriguez-Calcerrada et al. 2014), while overlooking the biochemical changes induced by recurrently increased drought. These biochemical changes concern in particular the tree reserves of non-structural carbohydrates (NSC), which have a demonstrated importance for subsequent tree growth and survival to extreme drought events (McDowell 2011). They also concern the nutrient concentration and stoichiometry (Nitrogen, Phosphorus, and Potassium) in tree tissues, which subsequently affects photosynthesis and growth. The overarching aim of this project is to assess experimental possibilities for studying long-term precipitation manipulation (>10 years) impact on tree biochemistry while strengthening up the scientific relationship between the Forest Genetics and Ecophysiology Research Group (Technical University of Madrid, Spain) and the Research Group “Dynamique réactionnelle des ecosystèmes, Analyses spatiale et Modélisation” from the Centre of Functional and Evolutionary Ecology (CNRS, France). More specifically, the visit of Jesús Rodríguez Calcerrada will have the following objectives: 1) assess the sampling methodology for biochemical analyses at the TA (Puéchabon, with a long-term experimental manipulation of throughfall), 2) share experience and protocols for nutrient and NSC content analyses, and 3) discuss previously acquired data and prepare research articles.

Xylem CO₂ fluxes derived from wood respiration in drought-stressed trees (ResStress)

ExpeER TA Site: Puechabon, FRANCE
TA User (visit): Roberto Salomon Moreno, Forest Genetics and Ecophysiology Reserch Group, Technical University of Madrid, Spain (February, 2015 – 05 days)
Project Description: Mediterranean forests are expected to suffer more intense droughts based on climate change predictions. Reduced water availability limits stem respiration (RS) in Mediterranean forests (Rodríguez-Calcerrada et al., 2014) at the same time that autotrophic respiration acclimation in the long-term mitigates reductions in carbon use efficiency (Rambal et al., 2014). To accurately estimate RS, commonly assumed as the radial CO₂ efflux to the atmosphere (EA), internal CO₂ fluxes through xylem (FT) need to be taken into account since the transpiration stream transports a portion of locally respired CO₂ upwards (Teskey et al., 2008). Under water stress conditions, FT decreases due to inhibited respiration rates and reduced resistance to radial CO₂ diffusion because of the limited stem water content (Salomón et al., in prep.). Rainfall manipulation experiments provide excellent scenarios to investigate the role of water availability on FT and its interaction with EA in order to better understand and model the acclimation to drought of autotrophic respiration.
The objective of this project is to assess of how water deficit jointly affects FT and EA to accurately estimate RS in Mediterranean coppices of Quercus ilex in South France and Quercus pyrenaica in the Iberian Peninsula. Furthermore, this project would strengthen the relationship between the Forest Genetics and Ecophysiology Research Group (Technical University of Madrid, Spain) and the Research Group “Dynamique réactionnelle des ecosystèmes, Analyses spatiale et Modélisation” from the Centre of Functional and Evolutionary Ecology (CNRS, France).
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Genetic variability in tillering response of durum wheat to assimilate availability modulated by PPFD. TILLER.

ExpeER TA Site: MontpellierEcotron, FRANCE
TA User (visit): Fulvia Rizzi, Consiglio per la Ricerca e la sperimentazione in Agricoltura, Genomics Research Centre (CRA - GPG), Italy (February, 2015 – 05 days)
Project Description: The increase in biomass and grain production of 12 durum wheat varieties to elevated atmospheric CO₂ (570 ppm vs. ambient) tested with two years of FACE (Free Air Carbon dioxide Enrichement) was mainly related to increased tillering (Badeck et al. 2013). Similar results have previously been obtained for other crops (Gifford, 1977; Ziska et al. 2004; Shimono et al. 2009; Thilakarathne et al. 2013, Tausz-Posch et al. 2015). As most effects of elevated CO₂ have been shown to be mediated through variation of photosynthetic rates that cause downstream allocation changes, the most parsimonious hypothesis to explain the association between tillering response and biomass response, is that increased assimilate availability leads to increased numbers of tillers which provide an increased sink for further assimilates. The proposed experiment tests this hypothesis through variation of an other factor, the incident photon flux in a controlled environment and the related genotypic variability (Sanna et al. 2014).

Impact of CO₂ fixation by PEPC on carbon isotope composition of root-respired CO₂ in a C3 plant. (ISOPEP 2)

ExpeER TA Site: MontpellierEcotron, FRANCE
TA User (visit): Franz-W. Badeck, Consiglio per la Ricerca e la sperimentazione in Agricoltura, CRA-GPG , Italy (February, 2015 – 45 days)
Project Description: Carbon isotope composition of leaf bulk organic matter is often used as reference for photosynthetic discrimination in both plant and ecosystem level studies. However, we have shown that leaves are in general 13C-depleted compared to all other organs suggesting that post-photosynthetic discriminations do also occur. With an exploratory experiment (ExpeER fast track grant ISOPEP) we recently showed that one of the candidate mechanisms, i.e. a contribution of PEPc activity (re-fixation of CO₂ by PEP carboxylase via anaplerotic pathway) in heterotrophic organs can be detected with online measurements. The aim of the present proposal is to apply the new measurement system for investigating the role of PEPc activity in roots.

Legacy effects of crop management on pest suppressiveness of soils (SUPERSOILS)

ExpeER TA Site: Jena, GERMANY
TA User (visit): Heikki Hokkanen, University of Helsinki, Finland (February, 2015 – 05 days)
Project Description: We wish to determine how crop and soil management in agricultural systems affect the natural occurrence in the soil of the most important natural antagonists of crop pests – entomopathogenic fungi and nematodes. These components of functional biodiversity will determine the “suppressiveness” of soils towards pest insects. In our earlier studies (e.g., in the EU-MASTER project) we have shown that conventionally managed arable fields growing annual crops in Europe are practically void of these antagonists, but that different crop and soil management strategies support their existence. We also know that natural, undisturbed habitats such as forests and orchards harbour high levels of activity by these microbial antagonists of crop pests. The objective of this project is to use the existing long-term soil treatment experiments in Europe to determine whether the history of crop and soil management (‘legacy’) influences the diversity and strength of the antagonistic capacity (functional biodiversity) in agricultural fields.

Groundwater invertebrate drift at karst springs: a tool for assessing karst biodiversity and community dynamics (BIOKARST)

ExpeER TA Site: Zöbelboden, AUSTRIA
TA User (visit): Tiziana Di Lorenzo, Institute of Ecosystem Study, CNR - National Research Council of Italy (February, 2015 – 05 days)
Project Description: The subterranean environment harbours a unique fauna of unexpectedly high diversity.Thousands of species have been described from shallow and deep aquifers, hyporheic zones of streams and rivers, springs, caves and saturated zone of karst. Groundwater organisms (stygobionts) have long fascinated biologists because of its adaptation to the extreme conditions of ground water, such as their convergent morphology, loss of pygments and eyes, and the elaboration of extraoptic sensory structures. Groundwater communities are known to encompass most of the major taxonomic groups encountered in surface water habitats. Stygobionts exhibit a high degree of endemism and ecological specialization and are known today to be widespread, occurring in nearly all groundwater environments and throughout the world. However, information on their geographic coverage is still patchy and the biodiversity of this environment remains poorly known compared to that of freshwater surface habitats. Several aspects of the study of groundwater fauna create special difficulties, mainly related to the restricted access to the subterranean environments, such as karst systems. Many karst aquifers are often physically inaccesible due to the lack of extensive cave systems. However, collecting groundwater fauna at the outlets (springs) of a karst systems has proved to be a useful method to investigate the karst community and its biodiversity.
Groundwater species show different aptitude to dispersal, depending on their intrinsic expansionistic behavior, on micro-habitat location and species-specific dispersal capabilities and habitat preferences. Collecting groundwater drift at karst outlets such as spring has proved to give information about groundwater community dynamics, habitat partitioning and ecological preferences.
The aim of this project is to enhance the level of information about groundwater diversity and its dynamics through sampling groundwater drifts at the main outlets of a karst system. The Zöbelboden represents one of the best known karst catchment in Europe with long-term data series of the major components of its ecosystems. Moreover, sampling of chemical specimens is done by local staff at the main spring on a weekly base and through irregular sampling at all other springs. The project objectives are to integrate the chemical analysis by performing a preliminary biological sampling survey at the springs of Zöbelboden kasrt site, in order to collect the faunal drift. The results of the preliminary sampling will provide the first information of groundwater biodiversity at Zöbelboden site. Furthermore, based on these results, a regular sampling scheme could be proposed for further investigation aimed at assessing groundwater community dynamics and the ecological preferences of its species.

Identification of soil organic carbon thresholds for sustained soil functions in agroecosystems

ExpeER TA Site: Rothamsted, UK
TA User (visit): Lars Juhl Munkhorn, Department of Agroecology, Research Centre Foulum, Aarhus University, Denmark (February, 2015 – 05 days)
Project Description: The samples will be used for Johannes Lund Jensen’s PhD project with the title “Identification of soil organic carbon thresholds for sustained soil functions in agroecosystems”, and hopefully the bigger recently applied research project “Critical levels of soil organic Carbon for sustained soil functioning of arable soils (CritiCarb)”. The research aims at determining critically low levels of inherent soil content of carbon and improving our knowledge on added organic carbon for the purpose of restoring or sustaining soil structure. This is done by focusing on the ratio between mineral fines (<20µm) and soil organic carbon. We expect that this ratio identifies a functional threshold for soil physical behaviour as well as decomposability by microbes of labile organic matter.
We want to perform the research at the selected site because there is a broad gradient in soil organic carbon due to contrasting long-term land use. We plan to sample in plots with different long (>50 years) and short-term managements (AA, GG, AG, FG, GF, long-term fallow and arable). This will give us a gradient from the bare fallow treatment, which is highly degraded to the reseeded grass treatment, which is highly saturated in soil organic carbon.
Hypotheses: 1. The ratio between mineral fines (<20μm) and soil organic carbon can be used as an indicator of critical low soil organic carbon content for soil physical properties. 2. The ratio between mineral fines and soil organic carbon has an impact on the turnover of organic matter and hence the release of relevant nutrients for plant growth. 3. Addition of organic matter (flow) may restore soils with poor physical properties caused by unsaturation with organic carbon (low C stock).

Oxygen as missing link to respiratory quotient: measurement tests in the ECOTRON large scale lysimeters

ExpeER TA Site: Montpellier Ecotron, FRANCE
TA User (visit): Marian Kazda, Institute of Systematic Botany and Ecology, Ulm University, Germany (January, 2015 – 40 days)
Project Description: The 12 lysimeters of the ECOTRON macrocosms facility were filled with 2 m deep intact soil monoliths. Each six of them were planted with beans and cotton, respectively, and grown for 6 months. Previous measurements of CO₂ dynamics in lysimeter soils showed diurnal cycles of CO₂ concentrations. Such finding is supported by a recent study by Han et al. (2014) who found the daytime cycles of soil respiration being linearly correlated to plant photosynthesis with a lag of 1 to 1.5 hours. Therefore, our timely high-resolution measurements will provide a valuable information for both, the O₂ and CO₂ diurnal dynamics. Such high-resolution data can be used in a subsequent modeling of soil gas exchange processes.
After the cotton/bean experiment, the ECOTRON macrocosms lysimeters were harvested and the soil was not watered for 10 months during which maintenance and tests were done on the platform. These lysimeters are now in a rehydration phase and they will be planted with bean for a biological test of the heterogeneity within and between macrocosms. Such set-up also offers an unique possibility to test the various hypothesis related to CO₂ and O₂ dynamics in soil profiles while assessing the RQ. The planed CO₂ and O₂ measurements will test the following overall hypothesis: The soil respiratory activity and the oxygen consumption are directly related to the size of the plant pool (above-ground and below-ground biomass) and its metabolic activity. This approach will also offer a possibility for other projects, linking our results to the size and availability of plant-derived soil organic matter. The hypothesis will be tested using the following assumptions: - Soil CO₂ concentrations and the differences between soil pO₂ and pO₂ in the ambient air will increase gradually after the establishment of the plants.
- Soon after the planting, the soil RQ starts to increase up to nearly 1 due to metabolic activity of plant roots and supply of root exudates (Bare soil at the beginning of the experiment has a low RQ due to low-level microbial respiration based mainly on internal reserves and the use of recalcitrant carbon.) - Plant stress (i.e. drought) impair carbon fixation and decreases the supply of carbohydrates to below-ground and the soil microbiota starts to degrade more recalcitrant organic matter leading to lower RQ. Plant harvest will at first lead to increasing RQ due to fast mineralisation of fine plant roots and to nitrification, the later consuming O₂ without concomitant CO₂ production.
- Modelling of short-time changes in CO₂ and O₂ concentration gradients will reveal new insights into soil gas exchange such as sorption/re-sorption and temporary sinks for CO₂ and O₂ in soils.

Oxygen as missing link to respiratory quotient: measurement tests in the Ecotron large scale lysimeters (RESP_O₂).

ExpeER TA Site: Montpellier Ecotron, France
TA User (visit): Marian Kazda, Ulm University, Germany (November, 2014 – 3 days)
Project Description: Soil respiration (the sum of root and heterotrophic respiration) is highly dependent on plant cover, soil temperature and humidity. However, there are only few experimental approaches examining the response of soil respiration and its sensitivity to combined environmental effects such as warming and drought (Suseela & Dukes, 2013). Even though, vast majority of the studies are investigating solely soil respiration as release of CO₂ from the soil without considering oxygen consumption i.e. respiratory quotient (RQ=CO₂ eliminated/O₂ consumed). Direct oxygen measurements for estimation of respiratory quotients were done in comparatively few soil studies and moreover mainly in incubation experiments (Jenkins & Adams, 2011).
Furthermore, RQ is highly dependent on the origin of organic substances used by soil microbes. Readily degradable organic material gives a RQ ~ 1 but the degradation of more recalcitrant organic matter results in RQ < 1 (Dilly, 2003). In this respect RQ is also linked to the roots exudates, i.e. plant growth and metabolic activity. It is assumed, that about 20% of C assimilated by higher plants via photosynthesis is released by roots as exudates consisting of easily degradable hydrocarbons (Hinsinger et al. 2006).
It can be hypothesised, that soils with active and unstressed plants will have higher RQ but plants under severe stress such as prolonged drought will shut down the exudation of carbohydrates (c.f. Fuchslueger et al. 2014). Consequently, soil respiration will go back to less degradable organic compounds thus leading to a decline in RQ. However, drought stress-tolerant corn cultivars increased their root exudation under drought as a part of their stress acclimation (Song et al. 2012). Therefore, changes in the plant-soil-microbiota system under stress and their influence on soil respiration processes need further understanding.
The aim of the present study is to test the feasibility of implementing optical oxygen measurements into already existing assessment of soil CO₂ within the ECOTRON macrocosms facility. This should allow future tests of the hypothesis, that drought-induced changes in soil respiration also affect the respiratory quotient due to decreased input of root exudates.

Methane (CH₄) and nitrous oxide (N₂O) emissionsfromstemsofpine, spruce and birchtrees (MENOTREE)

ExpeER TA Site: Hyytiala, FINLAND
TA User (visit): Katerina Machacova, Global Change Research Centre, Academy of Sciences of the Czech Republic (October, 2014 – 17 days)
Project Description: The boreal forests with area of about 920 million ha represent 29 % of the total world forest cover. Based on soil chamber measurements, boreal upland forests have been considered to be an important natural sink of CH₄ and a natural source of N₂O. However, last year measurement campaign in boreal upland forest in Hyytiala, Finland, showed for the first time that Scots pine trees (Pinus sylvestris) can emit both N₂O and CH₄ from their stems and shoots and can significantly contribute to the N₂O and CH₄ exchange of the boreal upland pine forest (Machacovaet al. 2013a). Moreover, based on results obtained from the measurement campaign in Hyytiala from May to July 2014, spruce (Picea abies) and birch (Betulapendula) trees, as further important representatives of the boreal forest, emit both gases from their stems.The stem emissions seem to be dependent on soil water content. However, the question is whether all three tree species emit CH₄ and N₂O all year long.  
Therefore, the main objective of the proposed project will be to characterize and quantify the CH₄ and N₂O emissions from stems of P. sylvestris, P. abies and B. pendulain autumn after the loss of foliage by birch trees. We assume that CH₄ and N₂O emissions from stems of B. penduladecrease with loss of the foliage. This hypothesis is based on the assumption of a transpiration stream as a pathway for N₂O and CH₄ (Macháčová 2013b). The experiments will continue the successful measurement campaign in summer 2014 (financially supported by ExpeER project). The gas fluxes will be investigated on mature trees under natural field conditions using stem chamber systems and subsequent gas chromatographic analyses of emitted trace gases. Forest floor emissions of CH₄ and N₂O will be determined parallel to stem emissions to enable their comparison. Continuously measured micro-climatic data will be used for correlation analyses to investigate their effects on tree emissions of N₂O and CH₄. At the end of the campaign, the applicant will de-install the stem chamber systems installed in May 2014.

Contribution of belowground biomass carbon to stable soil organic matter pool (Maistable).

ExpeER TA Site: Tetto Frati, Italy.
TA User (visit): An Vanderhasselt, Ghent University, Belgium (September, 2014 - 3 days).
Project Description: Different agricultural management practices have been shown to increase sequestration of C in soil (Follett, 2001; Janzen et al., 1998). Crop residue management for example influences the retention of carbon in the soil.
In order to maintain soil fertility and –quality, or even improve it, it is important to supply enough organic matter to the soil. Only a smaller part of this organic matter also is on the decadal scale stabilized against microbial decomposition. Cereal crop residues are most often removed from the field and used as stable bedding or as a source for energy production. Yet there is growing interest to valorize grain maize straw for different potential purposes including bio-energy production, biorefining, construction material, ingredient of animal fodder…. By doing so, soil fertility or stable soil organic matter content should not be depleted, in order not to become a possible source of atmospheric CO₂. The increasing removal of aboveground crop residues increases the importance of belowground residues or roots. Recently, however, some field experiments have shown that the stable organic carbon pool in the soil is relatively unaffected by the removal of the aboveground biomass from the field (Monaco et al., 2008). Therefore, the intention of this research is to investigate the contribution of belowground biomass carbon to the stable soil organic matter pool. To this end it can be examined wheter belowground biomass is the major contributor to the stable organic carbon pool and which mechanisms are responsible.
The contribution of belowground biomass C to the stable organic matter pool is, however, not fully understood. Over the past 15 years increasing attention has been paid to investigate the relative stability of above- vs. belowground biomass derived SOC. From these research efforts it is now clear that root-derived C remains two times longer in the soil as stable SOC than shoot-derived C (Rasse et al., 2005, Kong & Six, 2010) However, the importance of several hypothesized mechanisms responsible for the stabilization of root-derived C and the interactions with agricultural management are not well understood.

3-D monitoring of simulated rainfall infiltration in natural soils.

ExpeER TA Site: Harz/Central German Lowland, Germany.
TA User (visit): Alessandro Arato, DIATI - Department of Environment, Land and Infrastructure Engineering, Politecnico di Torino (September, 2014 - 5 days).
Project Description: Infiltration of water from the surface and subsequent redistribution through the unsaturated zone is an important hydrological process, having implications for management of agricultural crops, soil drainage and groundwater recharge. Improved soil moisture management is crucial for sustainable improvement of food production and water supply (FAO, 2003).
Non-invasive characterization of flow and transport phenomena in the unsaturated zone gained importance in geophysical community in the last decades, contributing to the development of a branch also known as hydro-geophysics. More specifically, time-lapse non-invasive electrical resistivity tomography (ERT) has been recently applied to monitor flow and transport phenomena in soils at field and laboratory scale, soil–plant interactions in the root zone and gain a better understanding for modeling exchanges of fluxes in the soil–vegetation–atmosphere system (e.g. Binley et al., 1996, 2002, Garrè et al, 2010).
The integration of hydrological and geophysical measurements in a fully coupled 3D hydro-geophysical inversion seems a useful way forward to feed comprehensive hydrologic modeling tools with a suitable amount of good quality data (Romano, 2014). Moreover, we have a strong background on the application of resistivity tomography to environmental problems, since we worked in the recent years in the integrated characterization of NAPL-contaminated sites (Arato et al., 2013), and developed innovative tools for processing of  ERT data to increase the accuracy of the cross-hole tomographic surveys (Arato et. al. 2014).
We aim on testing the suitability of 3D inversion of high resolution electrical measurements at very small field scale for imaging infiltration patways in soils under natural conditions, towards the improved understanding of runoff response to rainfall in soils.
The Schäfertal study site, part of the Harz/Central German Lowland TERENO observatory (Zacharias et al, 2011) is a perfect test site for the proposed method because of the provided infrastructure (wireless soil moisture monitoring, time-lapse EMI measurements) and the resulting detailed knowledge on soil characteristics and soil moisture dynamics.

Simulation of water and snow dynamics at the Schäfertal catchment.

ExpeER TA Site: Harz/Central German Lowland, Germany.
TA User (visit): Marco Bittelli, Department of Agricultural Science, University of Bologna (ITALY) (September, 2014 - 5 days).
Project Description: The purpose of this research is to investigate the dominant hydrological processes at the Schäfertal catchment experimental site and to provide a broad description of the hydrological and environmental variables at the site. Moreover, we will investigate the relationships between the soil water and the soil heat balance, for a better understanding of the processes involved.
Specifically, the different hydrological processes are determined by a variery of processes, including geomorphological features, weather variables and their spatial distribution, soil properties, plant variables, soil management and so forth. Therefore to fully understand the processes taking place at a specific site, it is necessary to employ a broad approach, where all these components are considered. Because of the complexity involved in considering the system as a whole, and because of the non-linearity of many transport processes, a broad experimental and modelling is necessary.
This complex task can be reached by combining detailed experimental measurements and modelling. Our contribution to the current project is the modelling of the hydrological processes at the site. Our research group has developed an hydrological model (called CRITERIA) for multiscale applications. A simple one-dimensional version can be used at the plot scale, then a three-dimensional version can be employed for small catchments and then a regional scale version is available for regional studies. Some information and bibliographical information can be found at the website.
The use of a model developed by the same group involved in the project is a key component for a successful project, since we have the flexibility to modify and write new the code to include additional processes or modify the boundary conditions, depending on the specific site features, as needed.
The project will be developed in close collaboration with the XXXX group, performing the experiment at the site. Specifically, digital elevation data (DEM), weather, soil and plant data will be measured at the site. These data are necessary as input for the model. Moreover, the  groundwater table depth will be periodically measured to provide input as time-dependent lower boundary condition of the unsaturated zone.
In addition, this project will include algorithms into the model for computation of coupled heat, liquid water and water vapour transport in the vadose zone. The model will be tested by comparing the output data against soil temperature measurements performed at the site.
The project will enhance the understanding of a complex geo-hydrological system, by investigating the dynamics of a large variety of processes. The combined experimental and modelling effort will allow for identification of the dominant hydrological processes.

Impact of CO₂ fixation by PEPc on carbon isotope composition of root-respired CO₂ in a C₃ plant (ISOPEP).

ExpeER TA Site: Montpellier Ecotron, France.
TA User (visit): Franz-W. Badeck, Consiglio per la Ricerca e la sperimentazione in Agricoltura, Genomics research centre (CRA - GPG), Italy (September, 2014 - 5 days).
Project Description: Carbon isotope composition of leaf bulk organic matter is often used as reference for photosynthetic discrimination in both plant and ecosystem level studies. However, we have shown that leaves are in general 13C-depleted compared to all other organs (Badeck et al. 2005, see also Cernusak et al. 2009) suggesting that post-photosynthetic discriminations do also occur. Two of several hypotheses to explain this between-organ isotopic difference, are (1) opposite respiratory fractionation between leaves and heterotrophic organs, (2) higher PEPc activity (re-fixation of CO₂ by PEP carboxylase via anaplerotic pathway) in heterotrophic organs compared to leaves, etc. (see our recent review Ghashghaie & Badeck 2014). We have already validated hypothesis 1 (see references below) and the aim of the present proposal is to investigate hypothesis 2 on the role of PEPc activity mainly in roots.
An exploratory experiment to examine if CO₂-fixation by roots can be measured in situ will be conducted in September in the ECOTRON. Our model plant French bean will be used for these experiments for which we have already demonstrated the opposite apparent respiratory isotope discrimination between leaves and roots. The bean plants will be grown in small pots specially made for these experiments (pots have the inlet and outlet tubes allowing gas exchange measurements and isotope labelling of roots). The culture will be done in vermiculite with nutrient solution and the pots will be placed in one growth chamber of the Microcosmes platform in the Montpellier ECOTRON under standard environmental conditions. At the end of September, during a 5-days  measurement period  (the length of the Transnational access visit), on 3 week old plants, the top of the pots will be sealed to avoid exchange with the ambient air. Respiration rate and ¹³C exchange will be measured using the Ecotron CO₂ and ¹³C analyser with different inlet air to the root compartment for 3 different sets of plants (4 plants for each set): (i) CO₂ free air, (ii) air with normal CO₂ isotope composition at –8 per mil, and (iii) air with industrial CO₂ at –40 per mil. Del13C of net root respired CO₂ is expected to be invariable with changing ambient rooting volume CO₂ concentration and del¹³C if there is no CO₂ fixation via carboxylation reactions. Plants will be harvested at the end of the experiments for carbon isotope composition on root metabolites (malate, AOA, sugars) involved in the anaplerotic pathway and respiration and organic mass by Prof. Jaleh Ghashghaie (at the platform “metabolism-métabolome” of the IFR87, Université Paris-Sud, Orsay).
The proposed 4 week exploratory experiment serves to evaluate the feasibility of the use of the ECOTRON facility for online measurements (Barbour et al. 2007) of the ¹³C isotopic signature of root-respired CO₂ under varying concentration and del¹³C of air supplied to the rooting volume. Del¹³C of net root respired CO₂ is expected to be invariable with changing ambient rooting volume CO₂ concentration and del13C if there is no CO₂ fixation via carboxylation reactions. Variation of root-space gas composition will be used to separate CO₂ release during respiration from CO₂ fixation during anaplerotic carboxylation reactions. In case of a positive outcome it is envisaged to subsequently propose a full experiment to be done on the Microcosms platform. This full experiment will serve to study the role of anaplerotic root metabolism under variable N nutrition (Raven & Farquhar, 1990) for apparent fractionation of ¹³C in root respiration. The results of the experiment and of a potential full experiment on the successful test contribute to better characterize plant root gas exchange in the frame of studies of belowground gas fluxes (Brüggemann et al., 2011).

Response of isoprene emission and photosynthetic apparatus to urban stresses in sweet gum (Liquidambar styracifluaL.) ISOSWEET.

ExpeER TA Site: Bologna, Italy.
TA User (visit): Arkadiusz Przybysz, Warsaw University of Life Science, Warsaw, POLAND (September, 2014 - 13 days).
Project Description: Urban areas undergoes continuous and often adverse changes. Increased temperature, salinity and reduced water availability are major factors limiting plant growth. It has been predicted that drought periods will be even more frequent and severe in the near future, and these conditions will be especially pronounced in the cities. Salt is commonly used in order to de-ice roads. Solution can be appropriate design and maintenance of urban greenery. Unfortunately data on factors allowing plants to mitigate urban stresses do not cover all plant defence mechanisms. This project aims to study involvement of antioxidant system and photoprotective mechanisms in drought resistance. As most researches on plant antioxidants has focused on non-volatile compounds, in this work we will examine volatile organic compounds belonging to the isoprenoid family, which are also involved in protection against oxidative and other abiotic stresses. Isoprene is known as a thermal protectant to the photosynthetic apparatus. Moreover, these volatile isoprenoids, once emitted into the atmosphere, play a crucial role in the formation of tropospheric ozone and other oxidants, and increases the lifetime of greenhouse gases such as methane. For this reason isoprenoids emission may influence climate changes. Thus, in this project isoprene emission from plant will be investigated for both reasons, protective role against oxidative stress in plants and effect on air quality. The study object will be Liquidambar styraciflua, as this species is listed among high isoprene emitters and drought sensitive. The experiments will be performed on potted plants exposed to salt stress and drought cycles. Measurements of the efficiency of photosynthetic apparatus (i.e. gas exchange, chlorophyll a fluorescence), photosynthetic pigments (xanthophylls, chl a and b, lutein, β-carotene) and water status (transpiration rate, leaf water potential, relative water content) will be performed together with the analysis of isoprenoid emission potential to gain information on effect of applied stress on plant conditions and VOC emission. Efficiency of photosynthesis apparatus and transpiration will be measured in situ using a portable gas exchange system Licor 6400 set up also for VOC sampling. Identification and quantification of VOC will be performed by using a Gas Chromatograph-Mass Spectrometer and Proton Transfer Reaction-Mass Spectrometer. This study is continuation of last year work during which the isoprene emission and physiological responses of low isoprene emittor Cercis siliquastrum exposed to controlled drought were investigated.

COS as a new tracer for photosynthesis (photoCOS).

ExpeER TA Site: Hyytiälä, Finland.
TA User (visit): Dan Yakir, Weizmann Institute of Science (Earth & Planetary Sciences), ISRAEL (September, 2014 - 5 days).
Project Description: With this research visit, we aim at exchanging experience and information, and at developing collaboration on COS measurements as a novel tracer of photosynthetic CO₂ flux in two contrasting environments. Future applications of COS exchange for modelling photosynthesis and tree water relations will be discussed.
The expected results are to establish common methodology for COS measurement in Finland and Israel; make joint research plans for the incorporation of COS measurements into on going ecosystem research on the partitioning of ecosystem-atmosphere net CO₂ fluxes into its main components. Establish a new comparative research framework to assess the response of contrasting ecosystem to change: coniferous forests in high (Finland) and low (Israel) latitudes.
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Forest re-initiation (FoR).

ExpeER TA Site: Tatra Windstorm, Slovakia.
TA User (visit): Radek Bace, Department of  Forest Ecology, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences, CZECH REPUBLIC (August, 2014 - 15 days).
Project Description: The management practices all over the European national parks shifted towards non-intervention approach in the last decades. The transition raised a lot of concern about the future forest appearance and composition, because the scale and frequency of natural disturbances distinctly increased. One of the main issues is the precondition for successful survival of saplings in the mountain spruce forests. We propose to estimate the probability of survival and growth of spruce saplings, based on the impact of intraspecific competition (dependent on size and distance to the closest neighbor), as well as on the interaction with the growth substrate and vegetation composition. In 2011, we already founded 25 monitoring plots in the region of High Tatra National Park. The plots were situated in forest gaps subject to recent bark-beetle outbreak (for the majority of plots, in 2007). Our objective is to estimate the mortality and annual growth increment of spruce seedlings in order to elucidate the processes of successful stand re-initiation after natural disturbances in spruce mountain forests.
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Relationships between soil N₂O and NO Emission under Freeze-Thawing Events (REFTE).

ExpeER TA Site: Höglwald Forest, Germany.
TA User (visit): Ute Skiba, Natural Environment Research Council, Centre for Ecology and Hydrology - CEH Edinburgh, UK. July 2014 (1st stage) and September 2014 (2nd stage).
Project Description: Recently we have completed the TA project “Wintertime emission of Nitric Oxide from Soil” (WTENOS, P64) and confirmed the evidence (Laville et al., 2011; Yao et al., 2010) and importance of cold time NO emission in forest and arable sites. From our first assessment of 16 years of high resolution wintertime soil NO efflux data we know that contribution of cold time NO emission is significant with a contribution of up to 29% to the annual NO emission budget. Although wintertime soil temperature explained a larger part of the variation in NO efflux, peaks in NO efflux occurred during freeze-thaw events and very likely after snowmelt. Due to current lack in snow data, the latter however remains speculative. We further found evidence that NO and N₂O emission patterns overlap during distinct cold season periods. Surprisingly, up to date there are no published data regarding this challenge and focuses on the joint dependence of N₂O and NO emissions during freeze-thaw events. This is mainly due to lack of continuous data sets which include winter periods and due to the complexity of field measurements at sub-zero temperatures and snow cover as well as simultaneously measurements of N₂O and NO trace gases. It is well known that thawing frozen soils increases the availability of soil water content, thereby rehydrating cells, mobilizing soil nutrients and triggering metabolic activity of dormant or senescent microbial communities (Kieft et al., 1987; Schimel and Clein, 1996; Kemmitt et al., 2008; Kim et al., 2012). The magnitude of such effects seems to depend on the duration of the thaw period, rate of temperature increase, soil properties and climatic conditions (Balser and Firestone, 2005; Vargas et al., 2010) and thereby affect processes involved in the consumption and production of N trace gases such as NO and N₂O. Therefore, during winter, we assume to find correlations but maybe also offsets between N₂O and NO peak emissions, triggered by freeze/thaw or snowmelt.
In the proposed project we will use the recently generated high resolution dataset on NO fluxes in combination with those available N₂O raw data for selective representative years, which have to be re-proceeded in high resolution during that project. The main objective is to investigate retrospectively the evidence, frequency, magnitude and driving factors of cold time N₂O emission peaks and find relationships and determine offset with NO emission peaks in order to get an idea of possible interactions between of NO and N₂O production and consumption during winter. We will proceed, refine, combine and analyse N₂O and NO emissions, soil environmental and climatic long-term datasets from the Höglwald site, which is the only and thus unique research-monitoring station with continuous N₂O and NO flux data sets covering more than 16 years. Furthermore, we plan to further validate already analysed data, especially focusing on temperature and soil moisture data. We will compare and gapfill our temperature and rainfall data and add snow data from nearby research stations or weather stations. Our first TA project “Wintertime Emission of Nitric Oxide from Soil” enabled us to generate a basic dataset of high resolution NO fluxes. By analyzing the improved climate data and the new long-term high frequency soil NO and N₂O efflux data as proposed in this follow up project, we are very confident to come up with important findings which can be published in a high impact journal. The project will deliver also highly relevant data to further develop and refine the process descriptions of LandscapeDNDC for simulation of freeze-thaw driven NO emissions.

Changes in leaf inclination angle distribution with height for European deciduous broadleaf tree species.

ExpeER TA Site: Hesse, France.
TA User (visit): Jan Pisek, Tartu Observatory, Toravere, Estonia  (July/August, 2014 - 5 days).
Project Description: Leaf inclination angle distribution is a key parameter in determining the transmission and reflection of radiation by vegetation canopies. It has been previously observed that leaf inclination angle might change gradually from more vertical in the upper canopy and in high light habitats to more horizontal in the lower canopy and in low light habitats (McMillen and McClendon, 1979). Despite its importance, relatively few measurements on actual leaf angle distributions have been reported for different tree species. Importantly, when inverting canopy transmittance measurements for estimating the leaf area index or foliage clumping, incorrect assumptions on leaf angles may lead to considerable errors (Pisek et al., 2013).
The objective of this project is to collect vertical profiles of leaf angle inclination distribution for boradleaf tree species occuring at the Hesse site, France (i.e. European beech (F. sylvatica), horn-beam (C. betulus), oak (Q. robur), goat willow (S. capreae), silver birch (B. pendula), aspen (P. tremula) and wild cherry (Pr. avium). The obtained vertical profiles will be used to examine if the often assumed spherical leaf angle distribution is indeed a valid assumption for given broadleaf tree species in temperate ecoclimatic region. Next, the leaf angle inclination distributions from Hesse site will be compared with previously obtained profiles for co-occuring measured tree species (B. pendula, P. tremula) from Estonia in hemi-boreal ecoclimatic region to see if there might be any changes in leaf inclination angle distribution profiles with latitude. Effect of wind on changes in the leaf inclination angle distribution will be possibly also quantified. The results can be also used as an input for improved modeling of local carbon and energy fluxes.

Spatio-temporal vegetation signals of global change in Doñana wetland forests (WETFORSIG).

ExpeER TA Site: Doñana, Spain.
TA User (visit): Patricia María Rodríguez-González, Centro de Estudos Florestais, Instituto Superior de Agronomia, Universidade de Lisboa, Portugal (July, 2014 - 18 days).
Project Description: Doñana harbours the largest ibero-atlantic wetland forest under Mediterranean climate. Owing to its tight dependence of hydrologic regime, monitoring riparian plant communities is key, not only to track biological responses to local and global environmental changes but also to identify early warning signals of prospective changes in the ecosystem functioning which might affect other species and habitats. In 2002 we started a landscape scale monitoring protocol of riparian vegetation at Arroyo de la Rocina, Soto Chico and Soto Grande, using Landsat TM remote sensing of vegetation. In 2004, the project added a permanent plot network where community (species composition, structure) and environmental data are being recorded in the field every five years. In parallel, we are studying the spatial patterns of functional and phylogenetic herbaceous diversity across environmental gradients and the dendroecology of the main tree species.
Preliminary results of the Normalized Vegetation Difference Index (NDVI) through time revealed shifts in the riparian cover and suggest species-specific temporal signatures for the dominant trees. At the local scale (permanent plots), our data indicate increasing senescence of wetland population structure in la Rocina, associated to the particular persistence strategy maintained by the dominant trees (Salix). Our results so far give rise to new questions about the importance of the hydrologic dynamics, the regeneration patterns and the demogenetic structure of these forest populations if we are to understand their driving processes and to preserve their viability on the long term. Therefore, it is of utmost importance to keep up the riparian vegetation monitoring protocol in the long term, maintaining the remote sensing approach combined with the field sampling.
The general objectives of the research are characterizing the spatial and temporal variation trends in the community structure and in the ecophysiological processes occurring in Southern European wetland forests and to identify indicators of the whole ecosystem vulnerability.
Specifically the present proposal aims at:

• Performing a field validation of the preliminary temporal signatures of NDVI variation identified with Landsat TM images for the main tree species.
• Developing and testing a sampling design for the intermediate scale remote sensing of vegetation across the Doñana wetland forests, using the unmanned aerial vehicle (UAV) recently acquired by LAST-EBD.
• Carrying out the quinquennial sampling protocol of community composition and structure in the established network of permanent plots, to integrate the 2014 data with the 2004 and 2010 samplings and afterwards, combine the field with the remote sensing results.
• Exploring and tracking plant community responses and functional relationships of trees to environmental change.
• Reinforcing and enlarging the collaboration with local researchers in the long-term monitoring program development (Natural Processes Monitoring Team, LAST, LEM).

Holm oak phenology and relationships with acorn production (ACOPHEN).

ExpeER TA Site: Puechabon, France.
TA User (visit): Maria Dolores Carbonero, Institute of Agricultural and Fishing Research and Education (IFAPA), (June, 2014 - 57 days).
Project Description: Despite the influence of the acorn production to support livestock, wildlife and tree regeneration, little is known about their evolution over time and its relationships with meteorology or endogenous factors such as trade-offs between vegetative growth, phenology and masting. It is therefore very difficult to establish in what way the acorn crops will oscillate over the years. The objectives of this project are: determining the relationships between production of female flowers and acorns with meteorology, phenology, male flowering, vegetative shoot growth and nutritional status of the leaves. The experiment will be undertaken in southern Spain holm oaks located in a pasture farm in the province of Córdoba (University of Córdoba and Institute of Agricultural and Fishing Research and Education-IFAPA) and in the oak forest of Puechabon station, 35 km north of Montpellier (CEFE/CNRS). Data collection and analysis in Puechabon will be held on May 5th  to August 18th, 2014, coinciding with Tthe stay of Maria Dolores Muñoz Carbonero (IFAPA). We will analyze the correlations of female flowers and fruits in July with (a) phenology, (b) the intensity of male flowering, (c ) growth and thickness of the shoot in which the flowers are located, (d) the number of leaves of the shoot in which the flowers are located and (e) the chemical composition of the leaves of the shoot in which the flowers are located.

AGRISOM

ExpeER TA Site: Grignon and Lusignan, France.
TA User (visit): Marco Panettieri, IRNAS-CSIC Spain (June, 2014 - 30 days).
Project Description: Dr. Marco Panettieri, postdoctoral researcher at the “Institute of Natural Resources and agrobiology of Seville (IRNAS-CSIC)” together with Dr. Marie-France Dignac and Dr. Cornelia Rumpel of the “Institute for Ecology and Environmental Sciences of Paris (iEES-Paris)” are willing to establish a collaboration among them to evaluate the feasibility of a project focused on the study of the storage/degradation cycles of soil organic matter using high resolution spectrometric techniques.
The definition of “molecular recalcitrance” has been outdated by recent researches on the role played by organo-mineral interactions and microbial communities in SOM storage. The main goal of this project is to unveil how organic compounds interact with soil matrix promoting their preservation. To reach this objective, soil samples will be collected from the SOERE ACBB site Lusignan, in which a C3 to C4 plants conversion (prairie to maize cropping) has been established, and then analysed by high resolution techniques of spectrometry (GC/MS, GC/C-IRMS, CP MAS and HR MAS 13C NMR) and cutting-edge isolation methods. Samples will be taken from topsoil and subsoil, in order to distinguish from above and belowground biomass, and successively fractionated by sieving into aggregate size fractions, and by density separation into particulate organic matter fractions.
The applicant will travel to the iEES-Paris in three different periods of 10 days. During the first stay, scheduled from the 20th to the 29th of June 2014, Dr. Marco Panettieri will participate in the samples collection and preparation procedures. During the second stay, scheduled from the 10th to the 19th of July 2014, the protocols for the samples fractionation will be implemented into the iEES-Paris. The third stay, scheduled from the 8th to the 17th of September 2014 will be focused on the optimizing of mass spectrometry and nuclear magnetic resonance techniques for the analyses of the fractions of the sampled soil. The results will be used for the developing of future research projects.
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Vertical profiles of foliage clumping in Mediterranean evergreen forest.

ExpeER TA Site: Roma-Lecceto, Italy.
TA User (visit): Jan Pisek, Tartu Observatory, Toravere, Estonia (May/June, 2014 – 5 days).
Project Description: Clumping index (CI), quantifying the level of foliage grouping within distinct canopy structures relative to a random distribution, is a key structural parameter of plant canopies and is very useful in ecological and meteorological models. Recently, global foliar CI maps were developed using the multi-angle remote sensing data from Polarization and Directionality of Earth Reflectances (POLDER) instrument at 6 km resolution (Chen et al. 2005, Pisek et al. 2010), Moderate Resolution Imaging Spectroradiometer (MODIS) at 500 m resolution (He et al. 2012), and Multi-angle Imaging SpectroRadiometer (MISR) at 275 m resolution (Pisek et al. 2013). The vertical distribution of foliage and especially the effect of understory needs to be taken into account while validating foliage clumping products from remote sensing products with values measured in the field. Satellite measurements respond to the structural effects near the top of canopies, while ground measurements may be biased by the lower vegetation layers.
The objective of this project is to collect vertical profiles of foliage clumping for representative Mediterranean evergreen forest sites. No such vertical profiles are currently available for this ecosystem. The obtained profiles will be used for the validation and comparison of the existing foliage clumping products derived from remote sensing data. The results can be also used as an input for modeling local carbon and energy fluxes.

Effects of salinity on the leaf physiology and VOC emission of two contrasting grapefruit varieties (SALinGRA).

ExpeER TA Site: Bologna, Italy.
TA User (visit): Indira Paudel, Agriculture Research Organization, Israel (May/June, 2014 – 18 days).
Project Description: Effluents were main water sources since 10-15 years in world for irrigating of plantation especially in Mediterranean belt. Recently there are many reports of damage to plantations refracted in the gradual yield decreased up to about 75% compared with freshwater irrigation. In extreme cases there has been a breakdown the trees. Effects of effluents irrigation in plants are unclear. The negative impact of effluents on soil structure and high concentration of soluble organic matter in combination with excessive irrigation in heavy soils may lead to shortage of oxygen in the roots. And this element can affects directly on the hydraulic conductivity of root and shoots of many species and can may distract the photosynthesis apparatus of leafs. Thus, the main research goal is to identify and characterize the periodic and continuous application waste water irrigation in heavy soil and its response morphological to physiological effects on root and shoot level and possible in-depth cause in aspect to the water relation point of view.
Therefore, the aim of the project is to study the physiological response of grapefruit trees under different quality. Also, understanding the physiological aspects (gas exchange, Photosynthesis, chlorophyll florescence, mesophyll conductance, chlorophyll contents, carbon isotope ratio, root to shoot ratio and many other parameters) of grapefruit grown under different water quality in field and in green house conditions. For this, we have two experimental site in green house and in field conditions. Then, eco-physiological measurements, with portable or laboratory based gas exchange systems, Mass spectrophotometry (PTR_MS), minirhizctron studies will performed.
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Ecosystem service and dis-service analysis of rain fed and runoff harvesting afforestation (ECOFOR).

ExpeER TA Site: Negev, Israël.
TA User (visit): Jan Dick, Centre for Ecology & Hydrology (CEH), Edinburgh, UK. (May, 2014 - 8 days)
Project Description: The utility of ecosystem services as a concept for landscape planning is well established. However there is a need for research on indicators to assess the services both positive and negative (so called dis-services). A range of indicators have been proposed e.g. MA, TEEB and CICIES. These are high level classifications which provide an over view of the type of services which should be included and differ primarily on their treatment of the biological compenent of the service (biodiversity, primary productivity etc).
In this study we will directly compare two published lists one based on the MA and the other TEEB in a place-based assessment.
In this project we will work closely with in-country collaborators to compare two lists of ecosystem services (modified -Dick et al 2011 and Kandziora 2013) for two specific land uses in the Negev ExpeER site, Israel. The ecosystem services and dis-services of the rain fed afforestation and runoff harvesting afforestation areas of the site will be analysed. This work builds on the detailed measurements of ecosystem function collected by the site which are necessary to be able to utilise the Kandziora list of ecosystem service indicators. Additional services and dis-services will be added as appropriate.
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Testing the importance of the optimal canopy nitrogen distribution hypothesis for plant diversity effects in the field.

ExpeER TA Site: Jena, Germany.
TA User (visit): Dörte Bachmann ETH Zurich, Dept. of Environmental System Sciences, Institute of Agricultural Sciences, Switzerland (May - 5 days).
Project Description: A previous study by Milcu et al. (2014) found evidence for a positive relationship between the functional diversity of leaf nitrogen (N) concentration, carbon (C) uptake and derived efficiency measures. A higher functional diversity of leaf N concentration in the canopy of high compared to low diverse plant communities suggests an optimal vertical distribution of leaf N within the canopy in parallel to the vertical light extinction. This might optimize canopy photosynthesis, and eventually canopy C gain in accordance with the optimal-N-distribution-hypothesis (Anten et al. 1995). However, this assumption requires to be tested directly with field measurements. Therefore, within the planned project we would like to relate leaf N concentrations, canopy light extinction profiles and canopy C uptake measured at different height strata within the canopy to directly test the assumptions of the previous study by Milcu et al. (2014). The measurements will be carried out in plant communities of the Jena Experiment differing in their number of species to test the importance of plant species richness for the assumed relationships. The study will be a collaboration with teams of Germany (Jena, Leipzig, Freiburg) and France (Montpellier) and Switzerland.

Methane (CH₄) and nitrous oxide (N₂O) emissions from different tree species of boreal upland forest (MENOBUF).

ExpeER TA Site: Hyytiälä, Finland.
TA User (visit): Katerina Machacova, CzechGlobe Global Change Research Centre ASCR, Czech Republic (May, 2014 – 60 days).
Project Description: The boreal forests with area of about 920 million ha represent 29 % of the total world forest cover and 73 % of the world coniferous forests. Based on soil chamber measurements, boreal upland forests have been considered to be an important natural sink of CH₄ and a natural source of N₂O. However, last year measurement campaign in boreal pine forest in Hyytiala, Finland, showed for the first time that Scots pine (Pinus sylvestris) can emit not only N₂O but also significant amount of CH4 from stems and shoots (Machacova et al. 2013). This highly important finding revealed one of the missing unknown CH4 sources in the upland boreal forest of Hyytiala and can partially explained preliminary determination of small positive CH₄ fluxes above this ecosystem during summer time (Peltola et al. 2012).
The boreal forest of the experimental station in Hyytiala consists of a mix of Scots pine, European spruce (Picea abies), birch (Betula pendula) and common aspen (Populus tremula). To my knowledge, data on the CH₄ and N₂O emissions from three last mentioned tree species are not available; however, these are highly required for the understanding and quantification of trace gas fluxes in boreal forests.
Therefore, the main objective of the proposed project will be to characterize and quantify the CH₄ and N₂O emissions from stems of P. abies, B. pendula and P. tremula as affected by different soil humidity. Moreover, additional measurements on P. sylvestris will be performed. The gas fluxes will be investigated on mature trees under natural field conditions using stem chamber systems and subsequent gas chromatographic analysis of emitted trace gases. Forest floor emissions of CH₄ and N₂O will be determined parallel to stem emissions to enable their comparison. Continuously measured micro-climatic data will be used for correlation analyses to investigate their effects on tree emissions of N₂O and CH₄. Finally, the applicant will be involved in comparison campaign of static soil chambers used for measurements of N₂O emissions from soil.
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Using the Photochemical Reflectance Index (PRI) as proxy of seasonal variation in biogenic Volatile Organic Compounds (VOCs) emission capacity (PRITOVOC).

ExpeER TA Site: Hyytiälä, Finland.
TA User (visit): Josep Penuelas, CREAF/Universitat Autonoma de Barcelona, Spain (April, 2014 – 60 days).
Project Description: The purpose of the project is to evaluate the connection between VOC emissions, leaf pigment contents, pigment and terpenoid precursors (DMAPP), and the photochemical reflectance index (PRI) during the spring-to-summer recovery of photosynthesis in boreal Scots pine. The work is based on preliminary evidence that suggests that the PRI could be used as a remote sensing proxy of VOC emission capacity. This project validates the hypothesis in a real case scenario. The Transnational Access includes a 2 month visit for MSc. Chao Zhang to conduct leaf-level spectral measurements and collect needle samples in Hyytiälä Forest Research Station during the period 1 April 2014 - 31 May 2014, as well as a 1 week visit for Prof. Josep Peñuelas and Dr Iolanda Filella to start-up measurements and plan data analysis and upcoming publications. The resulting spectral and biochemical data will be combined with data from ongoing measurements in SMEAR-II/Hyytiälä Station: VOC monitoring, Gas exchange measurements, Chlrophyll fluorescence measurements, eddy covariance data, as well as tower based Spectral Reflectance. Hyytiälä offers the required infrastructure for this activity. This TA is part of a collaborative project between Prof. Peñuelas, Prof. Jaana Bäck (UHEL) and Dr. Porcar-Castell (UHEL). Pigment and DMAPP analysis will be carried out in Helsinki during summer 2014 in collaboration with Dr. Albert Porcar-Castell (UHEL). Analysis costs will be covered by ongoing projects of Bäck and Porcar-Castell. The visit is expected to yield at least one high-profile publication.

Nitrogen cycling in a peat land: the effect of different forms and loads of nitrogen deposition on N₂, NO and N₂O losses to the atmosphere (NitroWHIM).

ExpeER TA Site: Whim, UK.
TA User (visit): Eva Van Den Elzen, Radboud University Nijmegen, The Netherlands (April, 2014 – 5 days) - “Fast Track” Application.
Project Description: Peatlands represent an important and at the same time fragile carbon sink that is important with respect to climate change. Given the strong link between the carbon (C) and the nitrogen (N) cycle, the consequences of increasing anthropogenic N deposition is of concern for the sustainability of these ecosystems. Peat bogs are likely to be highly sensitive to enhanced nitrogen inputs, since they have evolved under conditions of restricted nitrogen inputs (Bobbink et al 1998) and peat mosses (Sphagnum spec., the keystone genus of peatlands) are able to outcompete other species by monopolizing nutrients and carbon (Lamers et al 1999; 2000; Fritz et al 2014). High N loads were shown to counteract this competitive advantage of Sphagnum and can result in leaching of N and opportunities for vascular plants to take over.
The Whim bog field study (CEH) is a long-term (since 2002) nitrogen application experiment in an ombrotrophic bog site in Scotland. At a relatively low background N deposition a free air release of NH3 and real-time additions of NO^3- and NH⁴⁺ in rainwater have been applied. The effects of these different N forms on biogeochemistry and physiological processes in Sphagnum peat have been studied since 2005 in active collaboration between CEH Edinburgh (Dr. L Sheppard and Mr. I Leith) and Radboud University Nijmegen (Prof. J Roelofs and Dr. L van den Berg).
Especially dry N deposition (NH3) was shown to cause strong declines of Sphagnum mosses (Sheppard et al 2013), as this form can easily become toxic at high concentrations and lead to N losses to the atmosphere as the greenhouse gas N_^¬2O. It seems to take a much longer time for wet deposition (in the form of NO^3- or NH⁴⁺) to have negative effects on peat bog vegetation. Because different species in the bog respond differently to the various N forms, defining critical loads for this ecosystem is challenging (Sheppard et al 2014) and soil chemistry seems to play an important role as well.
We now aim to add to these studies by studying the effects of different forms of N-deposition on total nitrogen dynamics of Sphagnum peatlands.  As the total nitrogen cycle and budget remains obscure du tor the lack of N output data, we propose to investigate the fate of the additional N once it leaches into the peat soil, and how the biogeochemical processes of denitrification and anammox are affected by the different forms and loads of nitrogen.

The relation between physiological responses of Sphagnum capillifolium and nitrogen losses to the ground water due to elevated atmospheric nitrogen deposition (NPLOSS_WHIM).

ExpeER TA Site: Whim, UK.
TA User (visit): Leon van den Berg, Radboud University Nijmegen, the Netherlands (April, 2014 – 5 days).
Project Description: Earlier studies have shown that the living Sphagnum layer filters nitrogen (N) by retaining and storing substantial amounts of N in biomass and peat (e.g. Lamers et al 2000). It was shown that the N-filter ‘’fails’’ at high N-loads resulting in N leaching to deeper soil layers where it can stimulate peat breakdown and growth of vascular plants such as sedges and grasses. Assimilation of especially the reduced N forms (NH⁴⁺ and NH₃) can become problematic to many mosses as these forms are toxic in high concentrations. Recently strong declines of Sphagnum mosses have been related to atmospheric N deposition in a long term N-manipulation experiment (Sheppard et al 2014) and decline occurred most dramatically in the plots that received reduced N as the dominant N form. Earlier work by our groups has resulted in an identification of physiological responses of the Sphagnum mosses to different N forms and N loads. A recent experiment (Fritz et al 2014) showed that N uptake rates decline over longer exposure time, probably due to physiological restrictions, and that uptake rates are N-form dependent. During short exposure time, uptake rates were high and N-filtering was near to 100%. In a follow-up experiment, dominant N form in deposition was also linked to phosphorus (P) uptake rates (van den Berg et al in prep) showing higher P uptake rates when oxidised N was the dominant N form in deposition. These findings have important ecological and evolutionary implications: at high N input rates, the risk of N-toxicity seems to be reduced by lower uptake rates of Sphagnum, at the expense of its long-term filter capacity and related competitive advantage over vascular plants. This implies that N losses (leaching) to deeper groundwater layers are expected to be higher where N input is higher or where N uptake rates are reduced by the mosses (i.e. where oxidised N is dominant and deposited in high loads). In addition, in P-polluted bogs, P levels are high and P may not be retained in the mosses when reduced N is the dominant N form. This may result in P leaching and higher P availability in ground and pore water where it can stimulate growth of vascular plants. The environmentally relevant and scientifically interesting differences in assimilation rates and physiological responses of Sphagnum peat under different N deposition regimes in relation to N and P losses to deeper ground water have, until now, not been studied in long term experiments.

Wintertime Emission of Nitric Oxide from Soil (WTENOS).

ExpeER TA Site: Höglwald Forest, Germany.
TA User (visit): Ute Skiba, Natural Environment Research Council, Centre for Ecology and Hydrology - CEH Edinburgh, UK (March/April, 2014 – 30 days).
Project Description: Rewetting of dry soils and thawing of frozen soils have similar short-term effect increasing the soil water availability that lead to rehydrate cells, soil nutrient mobilization and stimulating of metabolic activity of dormant or senescent microbial community (Kieft et al., 1987; Schimel and Clein, 1996; Kemmitt et al., 2008; Kim et al., 2012). Whereas the magnitude of such effects could depend on soil properties, vegetation type and climate condition (Balser and Firestone, 2005; Vargas et al., 2010). It is well known that during/after rewetting periods high NO emission peaks have been observed for different ecosystems (Guenzi et al., 1994; Hutchinson and Brams, 1992; Wu et al., 2010; McCalley and Sparks, 2008) and could contribute up to 80% of annual emission. However data regarding thawing effect on NO flux is still limited (Kim et al., 2012) mainly due to lack of continuous data sets covering whole year including winter period and due to complexity of field measurements under negative temperature and snow cover. At present time only sporadically, on an occasional basis, published data, regarding some evidence of NO emission during freezing/thawing periods could be found. Clear evidence of NO flux rising following thawing has been reported from cropland in France (Laville et al., 2011) and from laboratory incubation of four types of soils in Mongolia (Yao et al., 2010). Recently occasionally wintertime NO peaks were observed in Southern Ukraine during ECLAIRE project measurements (Medinets et al., unpublished data) as well as the same pattern was found after screening of Höglwald forest stand data (Kiese, pers. comm.). The main objective of this project is to investigate retrospectively the evidence, frequency, magnitude and driving factors of wintertime NO peaks as well as a significance for annual budget, analysing NO emission, soil environment and climatic long-term dataset of Höglwald site, which is the only unique research-monitoring station with continuous data set (including wintertime periods) covering more than 15 years of intensive investigations regarding soil-atmosphere exchange. Furthermore based on that knowledge we plan to develop and potentially conduct targeted laboratory/field experiments for further improvement of process understanding driving peak NO winter emissions across different ecosystem types. We suggest that despite of freeze-thaw events usually occur occasionally the contribution to annual NO flux magnitude could be significant and winter period of investigation should not be neglected.

BVOC measurements in a boreal forest using PTR-MS.

ExpeER TA Site: Hyytiälä, Finland.
TA User (visit): Dušan Materić, The Open University, UK (February, 2014 – 5 days).
Project Description: The aim of the short visit to SMEAR II, Finland, is to obtain valuable experience in the following areas: branch enclosure techniques for VOCs emission research, PTR-MS set up and its use for research in the field, dealing with issues connected to sample piping, simultaneous photosynthesis and VOC measurement in the field, application of gas standards in the open systems due the calibration, models for tower estimation of VOCs emission.Furthermore, potential long-term collaboration as a part of the applicant’s PhD project will be discussed together with associated logistics. It is expected that initial measurement will be done, as well.

Effects of residue management on NH3 losses in multi-plot trial (REMAL).

ExpeER TA Site: Tetto Frati, Italy and Lusignan, France.
TA User (visit): Andreas Pacholski, Crop Science, Kiel University, Germany (November, 2013 – 21 days).
Project Description: Livestock production contributes 70-80% of the anthropogenic ammonia (NH₃) emissions in Europe and application of manure contributes a large proportion of these losses. Many cost-effective abatement techniques have been proposed to reduce NH₃ volatilization in relation with manure spreading. However, common local manure utilization techniques need further investigation to promote best agronomic practices that reduce NH₃ volatilization.
Objectives: The first objective is the in-field quantification of NH₃ emissions from farmyard manure and cattle slurry applications on soil with and without maize residues, as they represent the most interesting treatments of the main experimental site for this issue. A second objective is a comparison among different methods for NH₃ emissions investigation.
Materials and Methods: in field NH₃ emissions will be measured for 3 days after surface application of cattle slurry, farmyard manure and for 2 weeks after application of urea on bare soil with and without maize residues (six treatments as total, with three replications).
Measurements shall be done according to a new multi-plot method developed in Germany (Gericke et al. 2011). Comparisons between treatments and replicate measurements are done by semi-quantitative sampling with acid traps. The obtained values are scaled to absolute losses by measurements with a calibrated chamber method (Pacholski et al. 2006). This approach has been proven valid compared to micrometeorological standard methods in several field trials in Germany (Quakernack et al. 2012, Ni et al. 2012). At some measurement campaigns micrometeorological measurements (Sommer et al. 2005) will be done to test the validity of the multi-plot approach under conditions of Northern Italy.

Functional and physiological divergence in lizards (LIZARUN).

ExpeER TA Site: Doñana, Spain.
TA User (visit): Antigoni Kaliontzopoulou, CIBIO/InBio, University of Porto, Portugal (October, 2013 – 11 days).
Project Description: Whole-organism performance, the ability of an organism to perform ecologically relevant tasks, is central to our understanding of how selection has shaped the morphological and ecological traits of animal species and, ultimately, the diversity we observe in different groups. Classic examples of whole-organism performance traits include bite force and locomotor capacity, which are relevant for basic ecological functions, such as prey capture, escape from predators, territory acquisition and habitat use. As such, they are directly linked to individual fitness and are under strong effects of both natural and sexual selection (Irschick 2003). A different, but tightly associated, type of performance traits encompasses physiological functions, such as body temperature and hormones. Both types of performance traits are highly integrated, as the interplay between physiology, morphology and behaviour defines individual functional potential and consequently fitness. While the above aspects of performance have received extensive attention, their relative influence on species activity and distribution patterns have been less explored. In the proposed study we will conjunctively study physiological and functional performance traits in three lizards from two different genera (Podarcis and Tarentola) with similar habitat requirements, but radically different thermal and activity patterns in order to compare the relative contribution of these traits in determining temporal and microspatial segregation between species. Specifically, we will measure bite force, locomotor performance, selected temperature and water loss rates and we will compare these traits across species. Additionally, we will examine if pairs of species with different activity patterns and ecological requirements are more differentiated in terms of functional or physiological performance, to obtain insight into the contribution of each set of traits in determining temporal and spatial segregation.
The project team has already performed similar experiments in previous occasions and all the necessary instrumentation is available in our research center. However, access to the Reserva Biológica de Doñana is essential for this project because the Doñana NP constitutes the center of geographic overlap between these three species. Further, previous investigation in this are facilitates data collection and provides the basis for the successful development of the project.
The data obtained will be presented in international conferences and integrated with other data that is being collected by the project team on the Podarcis hispanica and Tarentola mauritanica species complexes to be published in international journals.
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Effect of the Clean Development Mechanism Scheme on Dryland Afforestation and Farming (ECDMSDAF).

ExpeER TA Site: Negev, Israël.
TA User (visit): Henri Rueff, School of Geography, Oxford University, UK (October, 2013 – 10 days).
Project Description: It is widely acknowledged that tree plantations in deserts have potential for becoming important carbon sinks (Sedjo 1999, Gruenzweig et al. 2003, Lal 2004, Olschewski 2005, Ornstein 2009, UNCCD 2005). With a CO₂-enriching atmosphere, dryland trees improve their water-use-efficiency and hence become more resistant to drought and can be planted deeper into deserts. The UNFCCC reported that the Clean Development Mechanism (CDM) represented, as of June 2012, a $215.4 billion total investment while the Kyoto protocol had been extended until 2020. Rainfed agriculture at the edge of deserts faces high yield uncertainties. Desert farmers may benefit from renouncing wheat and plant rainfed trees instead to cushion risk and protect land from degradation, while securing a steady income from trading emission reductions through the CDM. It is currently unknown whether desert farmers in non-annex I countries may actually benefit from foregoing wheat for trees while capturing the high yield uncertainty of the former, characterizing desert agriculture. This project aims at answering this question by taking advantage of the knowledge acquired by scientists and foresters working in the Yatir forest, which is part of the Negev LTER. Yatir forest is unique in that it was planted in the early 1960s in the driest possible conditions for a large-scale afforestation project. Scientists and foresters working there have accumulated substantial experience in desert forest management and data. Nearby experimental farms have also measured wheat yields under various climatic conditions and can make this data available. The project shall compare, on an infinite time horizon, the net present value (NPV) of engaging in a small-scale plantation of Aleppo Pine seeking a reward from emission reductions and forest thinning by products, to the NPV of a wheat farm, which yields are predicted on an iterative simulation to capture weather uncertainties. Results shall have scientific relevance by providing a more accurate understanding of the worth of tree planting in desert under the CDM scheme when erratic weather and yields are fully integrated in the predictions. Findings will also have important policy relevance in understanding the minimum price of emission reductions needed for farmers to engage in the plantation of trees, and identify how transaction costs can be reduced. To carry out this research, Dr Henri Rueff shall visit Dr Moshe Schwartz at the Ben Gurion University of the Negev during 10 days, to acquire and analyse remote sensing data, interview foresters and scientists active in Yatir on the forest management, acquire forest yield data, acquire agricultural data, and interview dryland farming scientists and farmers.

Mircoclimate versus plant effects on relationships between soil CO₂ concentrations and efflux.

ExpeER TA Site: Montpellier Ecotron, France.
TA User (visit): David Reinthaler, Institute of Ecology, University of Innsbruck, Austria (October, 2013 – 21 days).
Project Description: Terrestrial ecosystems are an important component of the global carbon cycle whereas more than thirty percent of the CO₂ in the atmosphere is exchanged annually with the terrestrial biosphere (e.g. Ciais et al 1997). The two most important fluxes which regulate the carbon balance of terrestrial ecosystems are canopy photosynthesis and ecosystem respiration. The largest source of CO₂ from terrestrial ecosystems is soil CO₂ efflux that includes heterotrophic and autotrophic CO₂ (Schlesinger and Andrews, 2000, Bond-Lamberti & Thomson 2010). The role of soil CO₂ efflux from ecosystems in the terrestrial carbon cycle and its feedbacks to climate change is well known and has been shown to be influenced both by climatic conditions and plant activity (Janssens et al. 2001, Reichstein et al. 2003, Hibbard et al. 2005, Bahn et al. 2008). More recently it has been shown that the knowledge of CO₂ concentrations and CO₂ diffusion across the soil profile adds importantly to out understanding of mechanisms underlying soil CO₂ production and efflux (Pumpanen et al. 2008, Vargas et al. 2010, 2011), though a separation of plant-derived and microclimate-derived effects of soil CO₂ efflux is still not well resolved and requires further attention (Subke & Bahn 2010, Philipps et al. 2011).
The main aims of the of the project are 1) to test and validate a soil CO₂-profile-based system for assessing CO₂ production and diffusion across the soil profile and the resulting total soil surface CO₂ efflux in the large lysimeters of the Montpellier Ecotron, and 2) to separate effects of microclimate, soil physics and plant-related activity on soil CO₂ production and efflux and consequences for the net ecosystem exchange of CO₂.
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Changes in Soil Enzyme Activity and Microbial DNA Pool as a Result of Biochar (SEDNAB).

ExpeER TA Site: Beano, Italy.
TA User (visit): Amit Kumar Jaiswal, Agriculture Research Organization, Israel (October, 2013 – 11 days).
Project Description: Biochar, the solid high carbon product of biomass pyrolysis, is increasingly examined from scientific and commercial perspectives as a potential soil amendment. Biochar has the potential to change in soil pH, CEC, accumulation of organic C, and nutrient availability for plants. Such changes on the soil property can affect microbial diversity and biomass, and enzyme activities in soil. However, the impact may vary depending on biochar physiochemical properties, the amendment amount and time after the biochar applied (biochar ageing). Because the biochar research is quite young, there are few long-term, on-going biochar field trials that can be useful in this regard. In this respect, the Beano site in Udine, Italy, is quite unique. Biochar produced from wood was applied in 2008 to the Beano site, which had been under irrigated continuous cultivation for many years. The experimental plots (2 treatments: with and without biochar) have been maintained under the maize cultivation continuously since 2008. Thus, the Beano site affords a rare opportunity to explore the changes in soil enzyme activity and total DNA pool that may have resulted from biochar amendment.
The intent is to sample soil from upper 50 cm from the experimental plots and to extract and quantify enzyme activities and total double-stranded deoxyribonucleic acid (dsDNA) in the soil in order to see what impact exposure to biochar has made on a variety of enzyme activities and DNA pool. In particular, both extracellular and intracellular fraction of enzymes and dsDNA will be extracted by improved extraction procedure. The activities of the various enzymes such as arylsulfatase, β-glucosidase, leucine-aminopeptidase, acid- and alkaline phosphatase, will be determined using fluorescent analogues of each enzyme’s substrate on microplates. Similarly, the total dsDNA will be quantified fluorimetrically using PicoGreen® reagent on microplate reader. This work will be done in collaboration with Dr. Flavio Fornasier, Italy. Other analysis such as molecular weight of DNA and its fragment length distribution will be assessed by agarose gel electrophoresis depending on the results. The ultimate goal is to understand the biogeochemical effect of biochar after 5 years of application on nutrient cycles, plant pathogens, and plant growth.
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Radiative properties of organic-rich soils at the microwave L-band.

ExpeER TA Site: Eifel, Germany.
TA User (visit): Simone Bircher, University of Copenhagen, Denmark (September, 2013 – 2 weeks).
Project Description: Due to above-average rising temperatures a large amount of the frozen carbon sinks in the higher northern latitudes might be released, possibly causing a significant positive feedback on global warming. Thus, there is a strong need to monitor hydrologic processes, and given the hindered accessibility of these hostile environments, satellite observations constitute an essential tool. The Soil Moisture and Ocean Salinity (SMOS) mission carries the first space-borne passive L-band microwave radiometer operating at 1.4 GHz that is the preferred frequency for soil moisture retrieval. The latter is achieved by minimizing a cost function expressing the difference between brightness temperatures (TB) acquired by SMOS and modeled TBs by means of a radiative transfer model. The empirically-based model uses several land cover-dependent tuning parameters, which exclusively stem from study sites in dry and temperate climate zones. In order to improve our understanding of microwave L-band emissions in high-latitude environments and thus, supporting the quality of SMOS retrievals over these regions, the research project SMOSHiLat has been evoked in the framework of ESA’s Changing Earth Science Network. A database is created from data collected at the Sodankylä site of the Finish Meteorological Institute (FMI) in Northern Finland as well as at the Danish SMOS validation site established in the Skjern River Catchment in the framework of the Hydrological ObsErvatory (HOBE), including modeled as well as observed L-band radiative properties and state parameters. Using this information, an adapted emission model is developed and tested in the SMOS soil moisture prototype retrieval algorithm. The data sets of both test sites include continuous in situ soil moisture and soil temperature recordings as well as simultaneous tower-based (Finland) and airborne (Denmark) L-band radiometer TB measurements. Measurements of dielectric constants at L-band frequencies are carried out at the Laboratoire de l'Intégration du Matériau au Système (IMS) in Bordeaux, France. Even if situated less far north, the typical high-latitude environmental conditions including boreal forest, heathland and mineral soils with pronounced moss/lichen and decomposed organic litter layers on top are also encountered in Denmark.
The well-equipped L-band radiometer setup at the ExpeER site TERENO at the Research Center Jülich in Selhausen, Germany, offers highly controlled data acquisitions. By making use of this facility, the currently missing high-resolution TB data could be created for the Danish site spanning the entire range of encountered wetness conditions in order to complement the snapshot-like, km-scale airborne data. Thus, in the framework of the SMOSHiLat activities we would like to propose the following experiment at the Jülich site: Ground material excavated from the HOBE site, including the moss/lichen, organic and mineral surface layers is laid out in the 2 m × 2 m observation area of the L-band radiometer. The ground is completely wetted and subsequently shielded from natural precipitation. TBs are then acquired over an entire dry-down cycle accompanied by recordings of the essential state parameters (e.g. water content, temperature, soil properties). Furthermore, the experiment can be repeated for the individual layers. This activity would be of great value for the SMOSHiLat project as the development of the emission model could thus be based on more reliable experimental datasets from two different sites. For this reason, the proposed experiment would be highly supportive for the work towards improved understanding of the L-band emissions of high-latitude ecosystems, and the urgently needed high quality satellite monitoring.

Habitat use by a threatened long-distance migrant the Black-tailed Godwit Limosa limosa.

ExpeER TA Site: Doñana, Spain.
TA User (visit): Theunis Piersma, University of Groningen, The Netherlands (September, 2013 – 2 weeks).
Project Description: Doñana is a key stopover and wintering site for many waterbirds breeding in Europe. In addition to the seasonal natural marshes in Doñana, man-made ecosystems like rice fields, fish farms and salt pans provide alternative or complementary habitats that are used by migratory birds. Many species depend on this wetland and any loss or degradation could reduce waterbird populations in Europe considerably. The Black-tailed Godwit Limosa limosa is a long-distance migrant that is present in Doñana during the whole non-breeding period, especially during the winter season. Since the continental population has declined with more than 50%, much research has focused on the breeding ecology in the main breeding sites in The Netherlands. However, little is known regarding the ecology of the species during the winter. Most individuals winter in West Africa mainly in the wetlands and rice fields of Guinea-Bissau, but our recent studies have concluded that the number of birds wintering in Doñana has increased in the last decades. This positive trend of the population may be associated to the man-made habitat and could mitigate the negative effect of wetland loss and degradation in their large-scale geographical distribution. Consequently, knowledge about the habitat use of the species in Doñana is urgently needed given the importance of the area for the global conservation of the species.
Our main objective in this project is to carry out a survey to evaluate the importance of Doñana wetlands as a staging site for the threatened Black-tailed Godwit during the non-breeding period. In particular, we want to quantify the dependence of birds on the different natural and man-made habitats present in Doñana. The data of the habitat use of the Black-tailed godwit in Doñana will be collected from August 2013 to February 2014, based on UvA-bits transmitters and colour-ringed birds that have been previously captured at their breeding site. UvA-Bits was developed at the University of Amsterdam (www.uva-bits.nl) and allows for the precise tracking of transmitter-carrying individuals within a landscape as well as an accelerometer that allows for the continuous logging of feeding movements. This system will be able to track bird movement and behaviour in space and time, allowing to record at the same time field data on habitat use. In addition, as resource availability is one of the most important factors that determine the use of a wintering site we will also identify the main resources exploited by the birds in the different habitats. We expect to contribute relevant information to understand how man-made and natural habitats in southern Europe contribute to the conservation of Black-tailed godwits during the winter.

Soil organic carbon changes under different forest regimes (CaDiF).

ExpeER TA Site: Höglwald Forest, Germany.
TA User (visit): Tomasso Chiti, Univeristy of Tuscia/DIBAF, Italy (September, 2013 – 10 days).
Project Description: Forest management can actively induce changes in tree species composition, which have subsequent implications on the greenhouse gas (GHG) balance of forest areas. Despite carbon (C) dynamics in soils can be slow and changes in the stock detectable only after 5-10 years from a disturbance, soils are significantly influenced by forest management and the type of vegetation cover. Different forest species can induce substantial changes in the C inputs via a different amount of litter depositions and fine roots dynamics, affecting directly the SOC stock in both organic horizon and mineral soil.
The main objective of the project is to determine the variations in the SOC stock as a result of a different forest management in beech (Fagus sylvatica) and Norway spruce (Picea abies) stands included in the Höglwald forest. Both stands were planted 12 years ago following a clear cut of the former Norway spruce forest. A mature spruce forest stand will be used as a control. We will take advantage of the historical data on SOC concentrations and stocks, available from the different investigations which were and are carried out in the study area. Consequently we will evaluate the variations occurred as a consequence of the different forest management determining the actual SOC concentrations and stocks in the different stands.
A special focus will be given to the link between the SOC stock and its distribution in pools of different stability/liability. A SOC fractionation based on the magnetic susceptibility of the soil will be done in this purpose. This will allow to assess the differences in the SOC pools distribution related to the forest species composition.
The Höglwald forest represents an unique situation where to assess the SOC dynamics in relation to forest species composition, having a strictly controlled, documented and investigation-oriented management as well as a solid record of historical information on the GHG fluxes and SOC stocks that are fundamental to understand the C cycle in forest ecosystems.

Circadian regulation of leaf water fluxes (CIRFLUX).

ExpeER TA Site: Montpellier Ecotron, France.
TA User (visit): Juan Pedro Ferrio Diaz, Dpt. Crop and Forest Sciences-AGROTECNIO Center, University of Lleida, Spain (September, 2013 – 23 days).
Project Description: Act locally, think globally: do circadian rhythms in leaf mesophyll hydraulics affect terrestrial water fluxes?
Terrestrial water fluxes are largely dominated by transpiration, however, large uncertainties on the controls of stomatal conductance lead to poorly constrained global estimates of transpiration (Jasechko et al. 2013). At the diurnal scale, one of the major assumptions underlying studies of the exchange of water between terrestrial ecosystems and the atmosphere is that daily fluctuations in transpiration are driven almost exclusively by direct physiological responses to changes in irradiance, temperature, humidity and other meteorological factors. However, it is increasingly recognized that transpiration may also vary over time in the absence of variation in external forcing because of endogenous control from the circadian clock (Resco de Dios et al. in press; Resco et al. 2009). On the other hand, transpiration and stomatal conductance are tightly controlled by the hydraulic conductivity of the leaf (Tyree and Zimmerman 2002). Previous work from the applicant has shown that short-term changes in leaf hydraulics is mediated by the interplay between mesophyll conductance and the “scaled effective path length”, or the water pathway from the xylem to the site of evaporation, a key parameter in models describing isotopic enrichment of leaf water (Ferrio et al. 2009, 2012; Flexas et al. 2012). This regulation is likely to be at least in part determined by changes in aquaporin expression (Flexas et al. 2012).
In this context, the ExpeER stay, planned for two weeks, will allow to participate to an on-going experiment on cotton and bean mesocosms in the Ecotron, coordinated by V. Resco de Dios (Sidney University) and A. Gessler (Leibniz Institute Berlin), and aiming at testing for a circadian regulation of daytime transpiration at the leaf level that scales up to affect whole ecosystem water fluxes, and to disentangle the underlying mechanisms. More specifically, the aim of the stay is to:
1) Disentangling whether the mechanism by which the circadian clock controls stomatal conductance also influence the expression of different aquaporin families in the mesophyll, thus affecting either mesophyll conductance for CO₂ and H₂O, or both ;
2) Compare circadian rhythms of leaf lamina hydraulic conductance and the scaled effective path length, as proxies for mesophyll conductance for H₂O, with the time-pattern of transpiration, mesophyll conductance for CO₂ and aquaporin expression, which will be determined by the other participants in the experiment.

Inter- and intra-specific differences in decomposition of Sphagnum litter under exposure to reactive nitrogen compounds (DeSNi).

ExpeER TA Site: Whim, UK.
TA User (visit): Sirkku Manninen, University of Helsinki, Finland (September, 2013 – 25 days).
Project Description: Earlier studies performed at the Whim bog show that the red (open grown) and the green (shade grown) type of Sphagnum capillifolium differ in terms N concentration, C:N ratio, pH, and their responses to elevated wet deposition of NH⁴⁺-N and NO^3- -N. Moreover, there are differences in the responses of S. fallax (green) and S. papillosum (yellowish – greenish brown) to elevated wet deposition of reactive N at Whim bog.
Peatlands are very important for C sequestration, but only if decomposition rates are low. Sphagnum litter is resistant to microbial, because it is rich in phenolics. Decomposition of Sphagnum litter has been found to be enhanced under exposure to elevated wet N deposition. However, adding N and NPK decreased S. capillifolium litter mass loss at Whim bog. This may be because the red type contains an anthocyanin called sphagnorubin (polyphenolic compound). The effects of N availability on litter peat decomposition may be connected through the activity of phenol oxidase, one of the few enzymes able to degrade polyphenols.
The long-term Whim bog N manipulation experiment offers an excellent possibility: i) to show potential differences in litter decomposition rate and subsequent CO₂ emissions between red and green pigmented S. capillifolium as well as between Sphagnum species, in response to long-term (>11 years) N inputs, (ii) to study inter- and intra-specific differences in the litter decomposition rate and subsequent CO₂ emissions of Sphagna under elevated wet deposition of NH⁴⁺-N cf. NO^3- -N as well as NH₃, and iii) to study which characteristics of the moss litter play a key role in terms of its decomposition rate and subsequent CO₂ emissions.
The project includes: peat litter incubations and CO₂ measurements, analyses of litter total C and N concentrations, measurements of DOC released from peat litter and water soluble phenol concentration, assays for activity of phosphatase and oxidative phenol oxidase, and use litter bags to study liteer mass loss.
The Centre for Ecology and Hydrology in Edinburgh has all the instrumentation to perform the study. Data will be gathered and analysed by the applicant (supported by staff at the site).
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Impact of summer drought and plant diversity on free-living soil nematodes (NEMADRYS).

ExpeER TA Site: Jena, Germany.
TA User (visit): Marcel Ciobanu, Inst. of Biological Research, Dept of Taxonomy & Ecology, Romania (September, 2013).
Project Description: Nematodes represent a major component of soil biota, interacting with other groups of soil fauna through multiple trophic pathways, and their influence on ecosystem processes is well documented. The trophic structure of the nematode community is a reliable index of soil food web structure, particularly in relation to decomposition pathways. Based on these characteristics, an understanding of nematode community responses (as well as those of other groups of soil fauna) to altered precipitation patterns and plant diversity may help predicting ecosystem-level responses to environmental change. The major aim of this study is to investigate interactive effects of drought and plant diversity on soil food web structure and functioning in Central European mesophilic grassland. The project will study how nematode communities respond to experimentally induced summer drought and plant diversity and will explore the possibility of using drought-related changes in nematode fauna as a tool in modelling ecosytem-level responses to climate changes. Soil nematodes will be sampled in selected plots of the Jena Experiment (Germany). They will be extracted using a modified Baermann method and preserved in 4% formaldehyde. The number of extracted nematodes in each sample will be counted and about 150 individuals (if available) will be identified to the genus level and assigned to trophic groups (plant feeders, bacterial feeders, fungal feeders, predators and omnivores). Different ecological indices for nematode communities will then be calculated and interpreted. Multivariate statistical analyses to detect patterns of relationships between nematode fauna, drought and plant diversity will be carried out by using the rich pool of biotic and abiotic explanatory variables available in the Jena Experiment, as well as statistical ecological modelling to investigate ecosytem-level responses to plant diversity and soil water shortage.

Effects of long term addition of reduced and oxidised nitrogen on the amino acid composition and nitrogen assimilation of Sphagnum capillifolium at Whim bog. – AminoWHIM.

ExpeER TA Site: Whim, UK.
TA User (visit): Leon van den Berg, Radboud University Nijmegen, The Netherlands (August, 2013 – 3 days).
Project Description:
Introduction: Bog vegetation reacts slowly to small increments of nitrogen (N) availability as the living Sphagnum layer filters N by retaining and storing substantial amounts of N in biomass and peat (e.g. Lamers et al. 2000). High total N loads were, however, found to have detrimental effects on biomass production of mosses (Arroniz-Crespo et al. 2008; Limpens et al. 2011) and result in direct physiological changes in Sphagnum mosses (e.g. Rudolph et al. 1993; Pearce et al. 2003). The relative effects of airborne ammonium (NH⁴⁺), ammonia (NH₃) and nitrate (NO^3-), have received much less attention.N uptake by Sphagnum mosses is accompanied by proton or base cation excretion, depending on the form in which N is assimilated (reduced or oxidised). Assimilation of especially the reduced N forms (NH⁴⁺ and NH₃) can become problematic to many plants and mosses as these forms are toxic in high concentrations, and result in a vegetation decline when loads are excessive (e.g Sheppard et al. 2009). In order to detoxify the reduced N forms, plants and Sphagnum mosses store excessive N in N-rich amino acids in the cells. N-rich amino acid accumulation may therefore act as a strong bio-indicator of stress in Sphagnum mosses due to increased N availability and may even act as an alarming signal for future declines of the mosses.Losses of base cations may be problematic for mosses that assimilate an excess of oxidised N forms, especially in the long term. Recently strong declines of Sphagnum mosses have been related to atmospheric deposition of nitrogen in a long term N-manipulation experiment (Sheppard et al. submitted). However, the environmentally relevant and scientifically interesting differences in assimilation rates, detoxifying mechanisms and deficiencies that may develop as a result of either reduced or oxidised N have, until now, not been studied in long term experiments.
Whim bog experimental site: The Whim-bog field study (CEH) on an ombrotrophic bog is a long term (since 2002), near natural, N-application experiment at relatively low background N deposition. The application involves a free air release of NH3 and additions of NO^3- and NH⁴⁺ in rainwater. It can therefore provide evidence of the effect of different N forms under near natural conditions on Sphagnum species.There has been active collaboration between CEH Edinburgh (Dr. L Sheppard and Mr. I Leith) and Radboud University Nijmegen (Prof. J Roelofs and Dr. L van den Berg) since 2005 to study the differential effects of reduced and oxidised N on biochemistry and physiological processes in Sphagnum peat. In 2005, and again in 2008, amino acid concentrations were measured in Sphagnum capillifolium and these provided considerable information concerning the vitality of these species. All three N forms enhanced the amino acid concentrations with the N-rich amino acid arginine (4 N to every C) as the most dominant amino acid to detoxifying N. In the wet plots, both the 64 and 32 kg N ha^-1 y^-1 treatments significantly enhanced N-rich amino acid concentrations, with reduced N having a bigger effect than would be predicted solely from the higher foliage N concentration. The elevated concentrations are symptomatic of impending damage to the Sphagnum in these treatments despite the fact that there were no visible damage symptoms in 2005 and 2008 in the wet plots. In contrast, along the NH3 transect S. capillifolium was in a very poor state, which was also reflected in enhanced amino acid concentrations.
Objectives: Amino acid concentrations in S. capillifolium were analysed in 2005 and 2008, respectively 3 and 6 years after the start of the experiment. Since 2008, measurements of amino acid concentrations, base cation content and total carbon and N content of the plants have unfortunately not been repeated. We propose to reanalyse the amino acid content, base cation content and C and N content of the Sphagnum mosses in 2013 (11 years after start of the experiment) in order to obtain a full understanding of the physiological responses to long term application of the 3 different N forms. We aim to relate the long term application of different N forms to S. capillifolium to N-rich aminoacid content, base cation content, C and N content and vitality of the species.

Effects of long term addition of reduced and oxidised nitrogen on dinitrogen fixation and uptake of phosphorus and potassium by Sphagnum – microbe associations in peatlands.

ExpeER TA Site: Whim, UK.
TA User (visit): Eva van den Elzen, Radboud University Nijmegen, The Netherlands (12 August, 2013 – 3 days).
Project Description: Peatlands provide a very important, but at the same time fragile terrestrial carbon sink, and are therefore important with respect to global change. Research at the IWWR in Nijmegen has shown that the keystone genus (ecosystem engineer) Sphagnum in peatlands is able to outcompete other species by monopolizing nutrients and carbon in a very efficient way (Lamers et al., 1999; 2000; Fritz et al., submitted). This unique capacity seems, to a large part, be caused by its complex mutualisms with microbial partners, present on the surface and in the hyaline cells of the mosses.The mutualisms include photosynthetic carbon acquisition from methane, internally oxidised to carbon dioxide by methanotrophes (Smolders et al., 2001; Raghoebarsing et al., 2005; Kip et al., 2010), and dinitrogen (N₂) fixation from the atmosphere by cyanobacteria (Kip, 2011) and a large array of other bacteria that are capable of N₂ fixation. How this association between Sphagnum and N₂ fixing bacteria works, which environmental factors affect it, and what the effects are on the acquisition of other nutrients such as phosphorus (P) and potassium (K), is largely unknown.Peat bog ecosystems are likely to be highly sensitive to enhanced nitrogen (N) inputs, since their stability depends on their vegetation including symbiotic microbes evolved under conditions of restricted nitrogen inputs (Bobbink et al., 1998). Recent studies in pristine Canadian boreal peatland showed that nitrogen deposition decreases N₂ fixation of the microbial community (Vile et al., subm.; Popma, 2012).The Whim bog field study (CEH) is a long term (since 2002) nitrogen application experiment in an ombrotrophic bog site. At a relatively low background N deposition a free air release of NH3 and additions of NO3- and NH4+ in rainwater have been applied. In addition, and unlike in many other experiments focusing on airborne N effects, effects of total NPK addition have also been tested. The effects of these different N forms on biogeochemistry and physiological processes in Sphagnum peat have been studied since 2005 in active collaboration between CEH Edinburgh (Dr. L Sheppard and Mr. I Leith) and Radboud University Nijmegen (Prof. J Roelofs and Dr. L van den Berg).We now aim to add to these studies by studying the effects of different forms of N-deposition and additional PK on total nutrient dynamics of Sphagnum peatlands, including dinitrogen fixation ability, phosphate and potassium uptake rates, and the composition of the microbial community that lives in association with Sphagnum.

Ectomycorrhizal short-root acclimation to soil warming.

ExpeER TA Site: Achenkirch, Austria.
TA User (visit): Ivika Ostonen, University of Helsinki, Finland (August, 2013 – 25 days).
Project Description: Ongoing climate change increases the temperature in forest soils and thereby affects soil carbon and nutrient dynamics. The development of an efficient fine root system is necessary for trees to ensure sufficient nutrient uptake in changing soil conditions. Thus, trees must acclimate by modifying the morphology of short roots with primary structure, which are mainly colonized by ectomycorrhizal (EcM) fungi and responsible for water and nutrient uptake. Morphological plasticity of ECM short roots is the fastest mechanism for root acclimation in trees, which enables them to survive in a changing environment. We aim to study changes in EcM short root morphology in relation to higher soil temperature and the experimental site at Achenkirch provides a great opportunity to assess potential warming effects on EcM short roots of mature spruce trees. The analysis of the results will give valuable information on general tendencies in acclimation of nutrient absorbing EcM short roots to warmer soil conditions. Shifts in short root morphology may influence the functional dynamics of tree fine root system, its associated mycorrhizae and the rhizosphere, and play a key role in C allocation and nutrient cycles of forests in the future.

Unmanned aerial vehicles for grassland and crop monitoring.

ExpeER TA Site: Eifel, Germany.
TA User (visit): Stefanie von Bueren, Massey University, New Zealand (August, 2013 – 26 days).
Project Description: In February 2013 a COST Action ES0903 supported scientific mission in collaboration with Andreas Burkart from the science centre in Juelich was successfully accomplished in New Zealand. Field experiments focusing on sensor intercalibration of multispectral and hyperspectral sensors on board of Unmanned Aerial Vehicles (UAV) were conducted over pasture paddocks. Results show that UAV mounted sensors deliver spectral information with high spatial and spectral accuracy. Furthermore, an initial experiment to estimate vegetation biophysical parameters such as biomass and quality parameters has been conducted and results indicate the feasibility of using UAV based remote sensors for fast and efficient derivation of such parameters. With the proven feasibility of this new technology, it is now essential to extend the field experiments over different grasslands and croplands during Northern hemispherical summer to build up a solid database for biophysical parameter extraction. The goal is to use the same sensor and UAV configurations as in New Zealand and conduct extensive field sampling of variable grass and crop fields. Hyperspectral sensors such as the ASD FieldSpec Pro as well as targeted vegetation sampling will be used for reference.
UAV can immensely improve our understanding of vegetation dynamics and support the calibration of air- and space borne remote sensing products. This work is seen as an opportunity to work at the head of the fast emerging applications of UAV for scientific research and it is expected that results will be communicated to the scientific community via publications and presentations.
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Cellular and enzymatic activity and proteomics in N-treated lichens.

ExpeER TA Site:: Whim, UK.
TA User (visit):Silvana Munzi, University of Lisbon, Portugal (April/August, 2013).
Project Description: Although several studies exist about lichen physiology in relation to nitrogen (N) availability, few of them investigated the consequences of short- and long-term exposure to N at cellular and molecular level. The main aim of this project is to contribute to fill this gap.
The Whim Bog, with N manipulation experiment which has been providing wet and dry deposition to ombrotrophic bog vegetation containing the matt forming lichen Cladonia portentosa, showed to offer suitable conditions to study both long-term and short-term effects. Our previous experiments carried out at the site allowed the ecophysiological consequences of long-term exposure on in situ thalli of C. portentosa and of short-term exposure on transplanted thalli of the N-sensitive Evernia prunastri and the N-tolerant Xanthoria parietina to be studied. Results provided important clues mainly on the relation between N availability and pH changes in lichens, the different effects of dry and wet N depositions, and the role of phosphorus and potassium in alleviating N toxicity (papers in preparation). We retain that a more exhaustive comprehension of the cascade of reactive N through the ecosystem cannot leave molecular and metabolic analysis out of consideration. Consequently, in order to answer the question: what are the cellular processes that determine the physiological response to and the ecological impacts of increased availability of reactive N, we propose:

• to repeat the collection of in situ material for long-term and the lichen transplants for short-term exposure,
• to verify the physiological performance of the samples,
• to observe (transmission electron microscopy) the ultrastructure of the two symbionts,
• to perform enzymatic essays,
• to make proteomic profiling of selected samples, and
• to integrate the data linking cellular and molecular observations, physiological response and ecological consequences.

Shrub-Tree INTeractions in peat bogs (STINT).

ExpeER TA Site: Hyytiälä, Finland.
TA User (visit): Juul Limpens, Wageningen University, The Netherlands (July, 2013 – 21 days).
Project Description: Peatlands cover only 3% of the Earth’s land surface but store approximately 30% of all terrestrial soil carbon (Turunen et al. 2002), particularly in moss-dominated peat bogs (Rydin & Jeglum 2006). Most peat bogs are situated at high latitudes in the northern hemisphere where climate warming is expected to peak (Solomon et al. 2007). Changes in temperature and precipitation patterns are expected to lower the water table and speed up peat mineralization with potentially profound consequences for the ecological functioning and plant species composition (Heijmans et al. 2013). Whether climate change can turn moss-dominated peatlands into shrub- or tree lands remains speculative. It has been hypothesised that expansion of shrubs and trees may set in motion positive plant-soil feedback (Ohlsen et al. 2001), accelerating succession into forest (Eppinga et al. 2009). However, current hypotheses do not take into account the effect of ericaceous evergreen shrubs, which often colonise dry microsites before trees arrive (Rydin & Jeglum, 2006). Shrubs can either facilitate or depress tree recruitment and growth (Berkowitz et al. 1995, Holmgren et al. 1997, Gómez-Aparicio et al. 2004, Holmgren et al. 2012), sometimes even arresting succession (Mallik 2003, Acacio et al. 2007).
We are conducting a field experiment to assess the interactions between shrubs and trees in Siikaneva. Preliminary results suggest that shrubs facilitate pine seedling recruitment. This research proposal aims to assess the ecophysiological performance, growth and survival of pine seedlings under different shrub density treatments in 2013.

FP7 EcoFINDERS.

ExpeER TA Site: Lusignan, France.
TA User (visit): Jack Faber, Alterra, Wagneningen University, The Netherlands; Paul Henning Krogh, Aarhus University, Denmark ; Peter Jorgensen, PJ-Bluetech ApS, Denmark (June, 2013 – 2 days).
Project Description: To further our understanding of the relationship between soil biodiversity and the functioning of soils, and how soil management may affect soil functioning in terms of provision of ecosystem services such as water infiltration and drought resistance. The ACBB field site provides excellent opportunities to compare various intensities of arable and grassland rotation management strategies as to the functioning of soils with respect to nutrient cycling, organic matter maintenance, soil structure, and hydrological regulation.
The results of various studies performed by the partners participating in the workshop need to be exchanged and discussed, so that our common understanding of the relationships between soil biodiversity and ecosystem services can be expanded.
We will discuss the need for further studies on site, and elaborate a workplan.
We will discuss possibilities for common publications.

Steps towards the conservation of hoverflies (Dipt.:Syrphidae) (STEPS).

ExpeER TA Site: Fruška Gora, Serbia.
TA User (visit): Antonio Ricarte-Sabater, University of Alicante (CIBIO Research Institute), Spain (June, 2013 – 30 days).
Project Description: Conservation of biodiversity is one of the main challenges in the world of today. Human activity has a long history in Europe and, as a by-product, native habitats have been modified, sometimes to the detriment of local biodiversity. Insects represent the largest proportion of the total biodiversity. Hoverflies (Syrphidae) are one of the most studied insect families in Europe; ecologically they are important pollinators and their larvae feed on plants, predate other insects and recycle decomposing material. However, they are also vulnerable to changes in their habitats or to inappropriate habitat management: some species are catalogued in red lists or are the subjects of national legislation. As with most insects, hoverfly conservation depends on how well species biology, ecology and regional populations are known.
Following a TA visit to Fruška Gora national park in September 2012, a second visit is now proposed from late June to late July 2013. This is to sample hoverflies and be able to analyse changes in the community over the course of the year, as well as to discover new biological information useful for species conservation. Data on adult sampling from 2012 and 2013 will be added to the historical series available at the University of Novi Sad. Comparison of data of the updated historical series will help to understand the current conservation status of selected hoverfly species in the park. The discovery of early stages and breeding sites of hoverflies such as those of the genus Merodon Meigen would reveal their requirements and they could then benefit from more effective conservation strategies. Because the habitats in Fruška Gora are well characterised, data on the association hoverfly/habitat will be recorded for the completion of the conservation tool, Syrph the Net data base of European Syrphidae. For the studies proposed in this TA visit, special attention will be focused on rare and poorly-known hoverflies found in the study area, including those species protected under Serbian legislation.

GeNetic status Of Eumerus: conServatIon implicationS (GNOSIS).

ExpeER TA Site: Fruška Gora, Serbia.
TA User (visit): Antonia Chroni, University of the Aegean, Greece (June, 2013 – 20 days).
Project Description: Assessment of species genetic structure is of high scientific interest due to its potential to clarify uncertainties on species’ taxonomic status and implicate species’ genetic variability in response to environmental alterations and evolutionary forces (Milankov et al. 2005a, Milankov et al. 2005b, Milankov et al. 2007, Milankov et al. 2008b, Ståhls et al. 2008). For instance, the quantification of genetic differentiation among populations of species in the family Syrphidae (Diptera) from a species diverse region such as the taxonomically daunting -but poorly studied- Balkan Peninsula is expected to reveal spatially and/or temporally fragmented populations, elucidating the species’ evolutionary history (Milankov et al. 2007). Most species are fragmented to a certain degree, depending on the environment (habitat fragmentation), species biology (dispersion, territorial behavior, character displacement) and historical events (genetic drift, founder effect, bottlenecks). At the same time, a genetic analysis at this level allows the detection of threatened species and recommendations regarding their management in the area by highlighting conservation implications for the preservation of the genetic diversity of these species (Milankov et al. 2008a).
One of the most primitive and diverse syrphid genera in the Palaearctic region is Eumerus (with 140 species (Peck 1988)) (Speight 2012). The vast majority of species within the genus remains taxonomically unclear, necessitating further in depth study (Speight 2012). We suggest investigating two species, Eumerus amoenus (Stackelberg 1961, Van der Goot 1981, Bradescu 1991, Vujić et al. 1999a) and Eumerus basalis (Stackelberg 1961, Vujić et al. 1999b, Vujić et al. 1999a) as they are the only common species on the study areas and are indicators of specific submediterranean habitats on Fruška Gora. Specimens of both species have been recorded in the hilly area of the Pannonian plain (Fruška Gora mountain, Serbia) and in the remaining Balkan Peninsula as well (A. Vujic and T. Petanidou, pers. comm.). Specimens of two populations (one of the south slope and one from the north of the mountain) of the E. amoenus and E. basalis will be collected from the FOMON site, while 10 populations are already collected from three different biogeographic regions on the Balkan Peninsula (Pindos mountain range, Metropolitan area of Athens and Lesvos Island, Greece). The Fruška Gora Mountain, Metropolitan area of Athens and Lesvos constitute «island» areas and could reveal/ form a gradient of isolation of Eumerus populations originating from the north to the south of the Balkan Peninsula. Fruška Gora has an elongated lens-like shape, 78 km long and about 15 km wide, with the highest peak at 539 m. Once an island in the Pannonian Sea (in the Pliocene period), today it is a biological mountain island on the Pannonian plain. It is made up of a variety of habitats such as dense deciduous forests and valleys, covered with meadows, vineyards, and orchards (Vujić et al. 2002), while in its outer boundaries, steppe vegetation is overgrown, rich in rare and relict species. Fruška Gora is a refuge habitat for Mediterranean and Atlantic species of hoverflies (Syrphidae) of the ancient Peripannonian region, consisting of 210 recorded species to date (Vujić et al. 2002) (Information: Institute for Nature Conservation of Vojvodina Province). The rest of the Balkan Peninsula is very mountainous (with very high elevations and severe climate) and densely forested, like the Pindos mountain range, where Eumerus populations have been collected. On the other hand, the site of Metropolitan area of Athens is an extended garden (600ha) within Athens metropolitan area and it can be considered as island. The third island population that we will use is from a very distinct, biogeographically and climatically, area: the Lesvos Island (1,632km^₂, northeastern Aegean Sea (Greece)). Lesvos is a real island, with a mild Mediterranean climate and a unique flora and fauna due to its volcanic origin and its vicinity to the Turkish mainland. The habitats are typically Mediterranean: mainly scrub, olive groves and coniferous forests. There is also a high number of hoverfly species: at least 110 sp. (Pérez Bañón et al. 1999-2000).
In this project, we propose to use two species of Eumerus populations, originating from a north part of the Balkan Peninsula and ending up to south.: two islands in a biogeographic sense (Fruška Gora Mountain and Metropolitan area of Athens), a real island (Lesvos, Greece) and Pindos mountain range, aiming to extract the haplotypes of both Eumerus species in order to elucidate the species’ phylogenetic status. The proposed project is a pioneer task of a larger study we are aiming to carry out over the next few years, in which we want to extend the geographic scope to many more “biogeographical island” sites of the Balkan Peninsula. In this future study, which is currently not financed, we aim to collect samples from mountains of the mainland Balkan Peninsula, such as Mt. Olympos and Mt. Erymanthos (Peloponnesus) and from other Aegean islands apart from Lesvos. The Laboratory for pedoecology and molecular laboratory at the Department of Biology and Ecology, at University of Novi Sad (part of FOMON) will host the applicant and provide access to its facilities. In addition, we will need to use the Environmental wireless sensor network from the EXPEER site CLIMATE CHANGE AND AIR POLLUTION IMPACT STUDIES FACILITY (FOMON) to obtain environmental data for the FOMON site.

Coupled Biochar-Soil Changes under Continuous Cultivation (BSCCC).

ExpeER TA Site: Beano, Italy.
TA User (visit): Ellen Graber, Institute of Soil, Water and Environmental Sciences, The Volcani Center, Agricultural Research Organization, Israel (June, 2013 –7 days).
Project Description: Recent years have seen a world-wide interest in the pyrolysis/biochar vision for renewable energy production, waste treatment, carbon sequestration, and soil fertility improvement. However, because the “Biochar Vision” is quite young, there are few long-term, on-going biochar field trials that can be useful in testing the carbon sequestration and soil fertility improvement parts of the vision. In this respect, the Beano site in Udine, Italy, is quite unique. Biochar produced from wood was applied in 2008 to the Beano site, which had been under irrigated continuous maize cultivation for many years. The experimental plots (2 treatments: with and without biochar) have been maintained under the same cultivation regime continuously since 2008. Thus, the Beano site affords a rare opportunity to explore the coupled changes that biochar and soil have undergone while under continuous cultivation.
The intent is to sample the experimental plots and to characterize the biochar particles and surrounding soil for a variety of chemical and physical characteristics. The original soil and biochar (samples of which have been preserved by the site directors) are also available for comparison. In particular, the various materials will be characterized in terms of organic matter content and chemistry (i.e., humic substances, small organic molecules, redox activity, mineral contents), and micro- and nano-structure (in collaboration with Dr. Stephen Joseph, Australia). Other qualities will also be characterized depending on the results of these tests. The ultimate goal is to understand the chemistry of biochar-soil- interactions 5 years after biochar application, and how these interactions may ultimately influence soil properties and fertility.

Surface fluxes in Semi AriD Environment (SSADE).

ExpeER TA Site: Negev, Israël.
TA User (visit): Eric Ceschia, CESBIO, France (June, 2013 – 12 days).
Project Description: The Center for the Study of the Biosphere from Space (CESBIO) is a laboratory that aims to develop knowledge on continental biosphere dynamics and functioning at various temporal and spatial scales. It is recognised worldwide for his expertise in remote sensing and surface flux measurements. CESBIO has recently developed new methods for 1) calculating GHGbudgets for crops by combining in situ GHG flux measurements and a Life Cycle Analysis approach and 2) for partitioning Evapotranspiration measured on the field into its components Transpiration and Evaporation. CESBIO is also developing models for estimating regional water and C fluxes by combining the modeling approach with remote sensing data.The Remote Sensing Laboratory (RSL) is currently part of the Department of Solar Energy and Environmental Physics, Jacob Blaustein Institute for Desert Research, Ben-Gurion University of the Negev. The laboratory aims at two main goals: 1) Advance scientific theories, methodologies, and applications in remote sensing, image processing, and geographic information system (GIS) management of the earth's resources. 2) Generate a scientific environment leading to the development of scientific exchange beneficial to the various disciplines of the institute. Satellite, aerial imagery, and ground data are applied to environmental problems with special emphasis on arid and semi-arid regions. This laboratory is in charge of the Negev Highly Instrumented Experimental (HIES) and Observational Site (HIOS). Our two laboratories already have strong collaboration in the field of earth observation by means of remote sensing since Gérard Dedieu (CESBIO) and Arnon Karnieli (Ben Gurion University) are co-Principal Investigators of the Venµs mission. The aim of this demand is to develop further some collabrorations and exchange of expertise between the two laboratories. In particular, we aim at increasing our collaboration concerning the experimental activities. As the CESBIO experimental sites are part of the ICOS and GHG Europe networks, our first goal is to characterize the Negev site and help the Israeli team to match the standards of the ICOS sites. Also those two sites will be used for validation of the Venµs remote sensing products and standardized equipment would help to validate the remote sensing products in contrasted climates. In a second time, we will help the Israeli team to adapt their methods for processing micometeorological data to the new ICOS standards and for partitioning the ETR fluxes as well as calculating the GHG budgets at their sites. Experimental data and information concerning field operations at the crop sites will be collected in order to finalise the calculations Those results could then be integrated in a synthesis paper concerning the GHG budgets for crops within the frame of the GHGEurope project. This paper should include the effect of albedo changes on the radiatife forcing of the crop sites. Discussion will be held concerning this methodology. Finally, in the perspective of the Sentinel 2 and Venµs satellite missions (launched in 2014) we will discuss and plan a common approach for estimating regional ETR and biomass production by using the SAFYE model (Duchemin et al. 2008) developed at CESBIO.

Compost effect on plant metabolism in stress conditions (ORGAMET).

ExpeER TA Site: Bologna, Italy.
TA User (visit): Maria de los Angeles Bustamente Muñoz, CEBAS-CSIC, Spain (June, 2013).
Project Description: The dryer and warmer conditions predicted for the Mediterranean basin in future decades (IPCC 2007) may alter plant ecophysiology and restrict growth and productivity. Despite being adapted to the environment, climate change may further affect the physiological activity of Mediterranean plants. In fact, Mediterranean summer drought is generally considered the primary constraint to the productivity and distribution of Mediterranean vegetation. Also, the increasing waste generation, especially from livestock production, and the difficulty of its disposal and management can imply an associated environmental impact. Thus, it is necessary to optimise the use of potential resources, such as these wastes, treating and recycling them to achieve sustainable crop production and to ensure the sustainability of the soil-plant system. Composting can constitute a suitable process to recycle these wastes, obtaining a stabilised and humified material that can be used with agricultural purposes or for soil restoration. Within this context, different studies have shown that compost application increases soil organic matter content, improving physical and chemical soil properties and thus, preventing soil erosion and plant drought stress. Also, although there are not many studies about the possible impact of soil amendment with compost on plant ecophysiology, it is known that compost application stimulates plant growth, and improves plant resistance to different kind of stresses, such as salt stress. Some studies have been also carried out on the effect of mineral fertilisation on biogenic volatile organic compound (BVOC) emissions, including isoprenoids, but little is known regarding to the use of organic materials.
Therefore, the aim of this project is to study the influence of the use of organic amendments on the plant resistance to drought by studying plant ecophysiology and BVOCs emission, these aspects being of great importance from the point of view of the restoration of degraded arid and semiarid soils. For this, potted plants of rosemary (Rosmarinus officinalis) will be grown in the control and compost-amended soils and they will be exposed to controlled drought conditions. Then, eco-physiological measurements, with portable or laboratory based gas exchange systems, and the analysis of BVOC emissions, by using Proton Transfer Reaction and Gas-Cromatograph mass spectrometers (PTR-MS and a GC-MS), will be performed.
Output : Drought and soil amendment effects on monoterpene emission in rosemary plants.
Nogués, I. ; Muzzini, V. ; Loretob, F. ; Bustamante, M.A. (2015) Science of the Total Environment 538 (2015) 768–778 - Download the pdf

Assessing ecosystem function by soil quality with hyperspectral remote sensing.

ExpeER TA Site:: Harz/Central German Lowland, Germany.
TA User (visit): Tarin Paz-Kagan, Ben-Gurion University, Israel (May/June, 2013).
Project Description: Hyperspectral remote sensing (HRS) is an advanced technique that provides near-laboratory-quality reflectance spectra of each single pixel. This capability allows the identification of targets based on their well-known spectral absorption features. The spectral information of the visible, near-infrared, and shortwave infrared (VIS-NIR-SWIR; 0.4–2.5 mm) spectral regions provides a promising capability to identify soil, vegetation, rock, and mineral materials. Hyperspectral remote sensing provides very valuable data for environmental research in different scales (laboratory, filed, landscape scale).
Evaluation of ecosystems structure - function is complex and needs an integrated methodology. Using soil quality, net primary productivity, and landscape pattern indicators can help evaluate ecosystems structure-function in landscape scale. Remote sensing applications provide great potential for monitoring indicators of environmental change and ecosystem function. The methodology guideline of this research is to examine the correlations between field indicator measurements and HSR in different scales (laboratory, filed, landscape). Studies with different spatial scales are significantly constrained due to limited data availability and have important value to ecosystems state.
Experiments on spatial and temporal behavior of soil quality indicators primary productivity, and landscape pattern indicators will be performed with hyper spectral images (0.4-2.5 mm) the spectral response of the different parameter will be carried out to logarithmic model. The spatial levels will be implemented by laboratory experiments, lifting platform within field, and airborne field campaigns. The data with different spectral and spatial resolutions should be tested in various ecosystems to understand their potential for estimating the methodological guideline and above-mentioned parameter.

Developing the methods for online BVOC measurements from boreal ecosystems.

ExpeER TA Site: Hyytiälä, Finland.
TA User (visit): Miguel Portillo Estrada, Dept. Plant Physiology, Institute of Agricultural and Environmental Sciences. Estonian University of Life Sciences, Estonia (May, 2013 – 4 days).
Project Description: The aim of this application is to strengthen the relationship between the field station SMEAR II in Hyytiälä (Finland) and the SMEAR station in Estonia, particularly in relation to ecosystem VOC exchange techniques with PTR-TOF-MS (Proton Transfer Reactor Time-of-Flight Mass Spectrometry). Our department has purchased one device and we need to learn how to use it from experienced scientists. This device analyzes the dynamics of sesquiterpene fluxes, and is capable of identifying these very reactive compounds in sufficiently short temporal resolution.
The visit to the field station SMEAR II will be driven by a training course on how to perform PTR-TOF-MS measurements of ambient air in the field. It also will provide first-hand information about the characteristics of the VOC exchange in the boreal coniferous ecosystem of Hyytiälä field station.

Carbon and water relations of grassland ecosystems at Park Grass.

ExpeER TA Site: Rothamsted, UK.
TA User (visit): Iris Kohler and Hans Schnyder, Technische Universität München, Germany (May, 2013 – 2 days).
Project Description: The visit will help facilitate the preparation of publications based on the earlier ExpeER proposal on “Carbon and water relations of grassland on the Park Grass Experiment” and will help identify potential opportunities for future collaboration; See details outlined in the ExpeER proposal on “Carbon and water relations of grassland on the Park Grass Experiment” completed in March 2012.
The visit will include discussions about past and future collaboration using the Rothamsted Long-term Experiments and Archives. It will also include presentations of preliminary work on “Carbon and water relations of grassland on the Park Grass Experiment” to Rothamsted staff by Professor Schnyder and Ms Köhler.
This visit will provide an opportunity to identify future collaborative work using the Long-term Experiments and Archives at Rothamsted and will help with the preparation of publications based on findings from the earlier ExpeER collaboration. First results show that the increase in Wi on the studied plots varied between 6.9 and 25.5 μmol/mol (1915 – 2009). A significant relationship between the increase in Wi and N supply was only found for the limed NO^3-N plots as reported in Köhler et al. (2012). The highest increases in Wi were observed on the unlimed NH^₄-N plots, but no significant relationship with N supply could be found. The difference between NO^3-N and NH^₄-N plots and limed and unlimed subplots indicates that other factors may play a role. Our previous study (Köhler et al. 2012) suggests that botanical composition may affect the response of Wi. This may be due to the greater responsiveness of grasses and will be investigated in future work: The average %-contribution of grasses to sward biomass varied between 49% and 99% and increased significantly (p < 0.01) with decreasing soil pH.

Partitioning of ozone deposition into stomatal and non-stomatal sinks.

ExpeER TA Site: Roma-Lecceto, Italy.
TA User (visit): Jennifer Muller, University of Manchester, UK (May, 2013 – 30 days).
Project Description: The aim of this transnational access is to investigate the partitioning of ozone fluxes in a Mediterranean forest ecosystem. All measurements suggested for this TNA are complementary to the ongoing long-term measurements of above canopy fluxes of CO2, CH4, H2O and O3 which are conducted by CRA in collaboration with CNR, and link to activities within the EU Marie Curie project EXPLO3REVOC (Ecophysiological control by Mediterranean forest ecosystems on the exchange processes of ozone and reactive Volatile Organic Compounds with a polluted atmosphere) at the Castelporziano flux tower site coordinate by Dr Fares.
While the long-term measurements provide data on total ozone fluxes, the partitioning of these fluxes is uncertain, especially in the field site in Castelporziano, where evaporative component from soil is large during all year due to a superficial level of fresh water table, therefore the calculation stomatal conductance based on inversion of Monteith equation in a “big leaf” approach is not advisable. During this TNA, below canopy sinks including ozone deposition to soil and reaction with NOx emitted from soil will be investigated. Specifically for this experiment, a second flux measuring tower will be installed, with a fast response ozone sensor provided by University of Manchester, fast H2O instrument and sonic anemometer for eddy covariance flux measurements available at CRA, and analysis of the gradient in the NOx concentration.
Stomatal ozone uptake will be calculated based on leaf level stomatal conductance measurements using a portable IRGA (Infra-Red Gas Analyzer, mod. LICOR-6400).
In-canopy sinks will be investigated using a 4-point gradient, allowing sequential sampling of ozone and NOx concentrations at the soil level, below the canopy and at in-canopy and above-canopy levels, which will aid interpretation of above and below canopy eddy covariance deposition fluxes.
An intensive campaign to estimate reactive VOC emissions from leaves and the calculation of ozone removal by these molecules will be done using a modified cuvette from LICOR-6400 and adsorbent cartridges which will be successively analysed by GC-MS (at CRA laboratory, Rome).
The TNA is suggested to take place over a several month period, with one month active period in Rome, i.e. installation of equipment (1 week), intensive VOC sampling (1 week), data analysis and modelling (2 weeks), removal of instruments (2 days). The fast ozone sensor is to be left at the site from May to September, with the aim to capture seasonality in ozone deposition processes which partly depend on biophysical conditions, i.e. observe a range of conditions from mild & warm (May), to dry & hot (August).
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Hydrological and biogeochemical modeling using LTER data.

ExpeER TA Site: Zöbelboden, Austria.
TA User (visit): Andreas Hartmann, Univeristy of Freiburg, Institute for Geo- and Environmental Natural Sciences, Germany (May, 2013 – 10 days).
Project Description: Due to the strong hydraulic heterogeneity of karst systems the simulation of their rainfall-runoff relationship provides a special challenge for model developers. In most karst regions, hydrologic and hydrogeological characteristics and spatial information about groundwater dynamics are extremely limited. The karst catchment “LTER Zöbelboden” in Austria provides excellent long-term data for model development and evaluation. The system is drained by several springs with strongly varying hydrological behavior that drain from the slopes or directly to the surrounding streams. To cope with this particular challenge, a model was developed that provides simultaneously the discharge of two surrounding stream sections and at two observation weirs within the system. To improve the degree of process representation, transport routines within the model are used to produce time series of hydrochemical compounds that are compared with the observations in addition to the discharge observations. That way, the uncertainty going along with the simulation of karst systems can be reduced. Additionally, it enables the model to provide solute balances at daily, monthly or annual time scales for the simulation period, as well as for future scenarios.

Gaseous nitrogen loss from biological soil crusts in desert environments (NgasLoss).

ExpeER TA Site: Negev, Israël.
TA User (visit): Bettina Weber, University of Kaiserslautern, Germany (May, 2013 – 10 days).
Project Description: Many deserts are characterized by high landscape diversity, i.e. marked patchiness in the distribution of vegetation. In the northern Negev Desert of Israel, at Sayeret Shaked Park LTER site, there are two main types of patches; 1) shrub patches consisting of herbs and shrubs on slightly raised mounds; and 2) biological soil crust patches consisting of algae, cyanobacteria, lichens and mosses that are characterized by the presence of a relatively impermeable soil crust. Plant growth in the shrub patches is observed to be strongly limited by nitrogen (N), while N fixing cyanobacteria are thought to contribute significant amounts of N to the biological soil crust patches. Runoff following rainfall events is expected to transfer N from the crust covered biological soil crust patches to the shrub patches.
As a result of severe droughts during the last years, the landscape within the LTER site is changing mainly due to the death of a significant fraction of the dominant perennial shrubs. For more than a year we have followed the biophysical developmental stages of BSC invading the sites of the dead shrubs. The proposed project will be conducted within this experimental setup.
Denitrification, an anaerobic respiration that reduces N oxides (NO^3-, NO^2-) to N gases (N₂O, N₂), is an important process, depleting biologically available N from drylands.
Our hypotheses are: 1) that biological soil crusts, covering the soil surface in these areas, play a crucial role in N₂O emission as they decrease the water infiltration rate and seal the soil surface; and 2) that N₂O emission differs between the different developmental stages of biological soil crusts, i.e. initial cyanobacteria-dominated versus well-developed lichen- and bryophyte-dominated crusts. We will test our hypotheses both in the field and in the laboratory.
Our goal is to confirm that BSC structures, which occupy arid landscapes following climatic change-induced vegetation reduction, may contribute significantly to the emission of greenhouse gases (nitrous oxide).

Response of nitrogen turnover to soil warming (Nitrowarm).

ExpeER TA Site: Achenkirch, Austria.
TA User (visit): Werner Borken, University of Bayreuth, Germany (May, 2013 – 25 days).
Project Description: Previous studies on soil warming revealed a severe increase in soil respiration which is linked through mineralization of soil organic matter to the soil N cycle. Consequently, we hypothesize an increase in soil nitrogen turnover as a result of soil warming. The study site Achenkirch (Austria) provides an excellent basis to study the long-term effects of soil warming in a temperate mixed forest of the Alps. The doctoral student, Marianne Schütt, shall measure the in-situ gross N turnover (ammonification and nitrification) in the top soil of the warmed (+4°C) and untreated control plots using the ¹⁵N pool dilution technique. After sampling, soil cores will be immediately treated with ¹⁵N labeled ammonium or nitrate solutions for 24 hours and then extracted with KCl solution. The extracts will be analyzed for ammonium and nitrate concentrations and the respective ¹⁵N signatures. Based on these analyses, gross and net turnover rates of nitrogen will be calculated for the warmed and control plots. In-situ gross N turnover rates will be repeatedly determined in August of 2013 because of seasonal dynamics. Results of this study may help to predict the availability of soil N in warmed soils and the potential N limitation of tree growth.

Ecophysiological responses of urban trees to drought condition (ECOTREE).

ExpeER TA Site: Bologna, Italy.
TA User (visit): Arkadiusz Przybysz, Warsaw University of Life Sciences, Poland (May, 2013 – 12 days).
Project Description: Green is a very important element of urban ecosystems which determines the quality of inhabitants’ lives. Unfortunately, the environment in which we live undergoes continuous and often adverse changes as a result also of human activities. It has been predicted by IPCC models (IPCC, 2007) that, because of climatic changes, drought periods will be more frequent and severe in the future, and these conditions will be even more exacerbated in urban areas. Data on factors affecting plant mitigation capacity often originate from experiments with seedlings grown in non-stressed conditions. Such data is not directly applicable to vegetation in urban areas. Thus, this project aims to study the involvement of the antioxidant system and of photoprotective mechanisms in drought resistance and adaptation of common species used for urban greening infrastructures in Italy (Bologna) and Poland (Warsaw). Although most research on plant antioxidants has focused on non-volatile compounds, certain volatiles belonging to the isoprenoid family have also been implicated in protection against oxidative and other abiotic stresses. Furthermore, these volatile isoprenoids, once emitted in the atmosphere, play a crucial role in the formation of tropospheric ozone. Thus, the emission of Volatile Organic Compounds (VOC) released by plants will also be investigated for their protective role against oxidative stress and for the effect on air quality. The studies will be carried out on urban ornamental species different in level of VOC emission potential and site requirements: Robinia. pseudoacacia and Liquidambar styraciflua as high VOC emitters and Fraxinus excelsior and Malus domestica as low VOC emitters. R. pseudoacacia and M. domestica are growing on dry sites, but L. styraciflua and F. excelsior prefer moister sites. The experiments will be performed on potted plants of these species exposed to controlled drought conditions. Measurements of the efficiency of photosynthetic apparatus (i.e. gas
exchange, chlorophyll fluorescence and photosynthetic pigments) will be performed together with the analysis of isoprenoid emission potential to gain information on how plants are coping with applied stress conditions. Photosynthesis and transpiration will be measured in situ using a portable gas exchange system set up also for VOC sampling. The chemical-physical analysis of volatile isoprenoids will be performed by using a gas chromatograph- mass spectrometer (GC-MS) and Proton Transfer Reaction-Mass Spectrometer (PTR-MS).
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Nitrous oxide (N₂O) and methane (CH₄) emissions from Pinus sylvestris and Populus tremula (NOME).

ExpeER TA Site: Hyytiälä, Finland.
TA User (visit): Katerina Machacova, CzechGlobe - Global Change Research Centre, Czech Republic (May, 2013).
Project Description: Nitrous oxide (N₂O) and methane (CH₄) are important greenhouse gases contributing to global climate change. N₂O and CH₄ can be emitted from surfaces of riparian plants. However, data on the emissions of these greenhouse gases by trees, especially by upland tree species, are scarce. To our knowledge, no data are available for coniferous tree species. Therefore, the main objective of the proposed project will be the characterisation and quantification of N₂O and CH₄ emissions from tree surfaces (stem and leaves) of Pinus sylvestris, representative of coniferous tree species. The gas fluxes will be investigated on mature trees under field conditions using chamber systems (stem and leaves chambers) and gas chromatographic analyses. Moreover, determined soil emissions of N₂O and CH₄ will be used for comparison with emissions of both trace gases from tree surfaces. Furthermore, measurements of sap flow rates will enable further correlation analyses with N₂O and CH₄ emission rates from P. sylvestris. Finally, the influence of soil and air characteristics (e.g. soil and air humidity and temperature) on trace gas emissions will be analysed.
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Scintillometry under advective conditions in a semi-arid ecosystem (DesertScint).

ExpeER TA Site: Negev, Israël.
TA User (visit): Hendrik de Bruin, Wageningen University, The Netherlands (May, 2013).
Project Description: Sustainable management of water resources in arid and semi-arid ecosystems requires accurate information on water utilization over a range of space and time scales. Water use in desert regions is highly variable in space and time. In effort to address this spatial heterogeneity, models yielding regional evapotranspiration (ET) maps were developed utilizing remote sensing imagery. Reliable validation of such models requires in situ measurement of the energy balance components at a spatial scale comparable to the satellites pixel size. Recently scintillometry was demonstrated to allow the measurement of sensible heat fluxes at footprint dimensions from 500 to 10,000 m, an area comparable with several pixels of a satellite image (tens of Landsat thermal pixels or a few MODIS thermal pixels). Under unstable conditions and for Bowen ratios larger than ~0.75, the method was proved to be reliable over homogeneous fields. Most of the experiments leading to this conclusion have been conducted in semi-arid areas. The need to expand agricultural land has brought many to develop agriculture in areas not naturally self-sustaining such activities. This has resulted in irrigated agricultural fields spread out in many semi-arid ecosystems. These irrigated fields yield high ET values, forming a sharp contrast with the dry surroundings. When the fields are an order of magnitude of several 10s of dunam local advection is likely to occur. The objective of this proposal is to study the ability of a displaced-beam laser scintillometer (DBLS) to measure mechanically generated turbulence under local advective conditions. The Negev LTER is located in a semi-arid region, where small irrigated agricultural fields are surrounded by dry natural ecosystems, creating frequent advective conditions. These conditions are ideal for testing the above defined research objective.
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Tillage operations & soil movement: Implications for long-term experiments (MOVE).

ExpeER TA Site: Rothamsted, UK.
TA User (visit): Kristof Van Oost, Earth & Life Institute / Earth & Climate Research Centre (TECLIM ), Belgium (April, 2013 – 10 days).
Project Description: Modelling and monitoring changes of phosphorus and soil organic carbon in long-term field experiments.
- Objectives: 1) To develop a flexible and robust model for describing and predicting tillage-induced soil and soil constituent (P, SOC) redistribution over time in long-term experiments. 2) To test a spectroscopic method for quantifying gradients in SOC across experimental plots using a low-cost unmanned aerial vehicle (UAV).
- Background: Tillage has been shown to cause considerable dispersion of soil and its constituents (e.g. Van Oost et al. 2000, Lane and McGrath, 1994, Sibbesen et al., 2000). This can have important implications for the integrity of long-term field experiments and the interpretation of treatment effects on the temporal change of soil properties, such as total P or SOC, in the plough layer. Depending on plot width and tillage intensity substantial amounts of the original soil will have left the plot area after 50 years. Van Oost et al. (2003) have developed a distributed model for predicting soil and soil constituent redistribution on sloping terrain. Here we propose to test this model for the well-documented management conditions of long-term experiments. With SOC contents dynamically changing in arable landscapes as a function of management, climate and topography, there is a need for developing low-cost methods for monitoring SOC contents in plough layers. Remote sensing methods based on multi-spectral images can map SOC variation (Stevens et al., 2009). Recently, the costs for UAVs and multi-spectral cameras have dropped dramatically opening an interesting perspective for flexible, local SOC mapping. With their pattern of distinct SOC contents in adjacent plots, long-term field experiments provide a very efficient experimental design/layout for systematically testing such a remote sensing approach for SOC.
- Plan: The Broadbalk experiment at Rothamsted is uniquely suited for this work. In 1990 total P in the plough layer was measured along a transect at high spatial resolution traversing several plots with contrasting soil P contents. Resampling this transect after a period of 23 years will (i) provide support for plot-to-plot movement in Rothamsted and (ii) provide unprecedented data to constrain and test a spatially explicit soil movement model. The advantage of this approach is that the initial conditions are well defined and that there are detailed records on fertilizer inputs, crop yields, P offtake and soil management. Additionally, Broadbalk provides the necessarily wide range of SOC for testing SOC sensing. In this project we plan to collect soil samples for TP and SOC analyses in selected parts of the Broadbalk long-term experiment. The soil data are used for model calibration and validation. We conduct aerial surveys of these areas with an UAV (low altitude c. 30-50m) and a multi-spectral camera testing an inexpensive spectroscopic method for mapping SOC. This work is collaboration between institutes from three countries and will require several field campaigns on Broadbalk starting spring 2013. Some of this research will be part of a PhD project.
Output: Aldana-Jague E., Goulding K., Hecktrath G., Macdonald A., Poulton P., Stevens A., Van Wesemael B., Van Oost K., 2014, High-resolution spatial patterns of Soil Organic Carbon content derived from low-altitude aerial multi-band imagery on the Broadbalk Wheat Experiment at Rothamsted, UK, EGU General Assembly Conference Abstracts 16, 12063.
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Strategies for better nutrient use efficiency and lower environmental load: from a long term field experiment to whole livestock farms (IMPROVEMAIZE).

ExpeER TA Site: Tetto Frati, Italy.
TA User (visit): Marina Bleken, Norwegian University of Life Sciences, Norway (April, 2013 - 13 days).
Project Description: Results from the long term trial on cropping systems at Tetto Frati will be used to estimate the yield and environmental performance of contrasting cattle farming practice in the Po Plain. The upscaling from crop system to whole farm scale will be modulated on the farm structure of real enterprises in the Piemonte area of the Po Plain. The characteristics of the herds and the degree of animal intensity will determine the need for forage and for disposal of animal manure, and results from the long-term cropping systems at Tetto Frati will be used to design feasible management plans for crop production and manure application on the farm. Data about important environmental indicators as nutrient leaching and soil organic matter changes will be estimated for the whole farm using response curves observed empirically at Tetto Frati. GHG emissions will be estimated according to IPCC methodology.
The objective of the study is to identify farming strategies for sustainable cattle production systems in the Po plain that comply with the requirements of the Nitrate Directives and Water Framework Directives of the European Union, as well as estimate their impact on GHG emissions.

Improving Doñana’s contribution to BCE (ButterflyDoñana).

ExpeER TA Site: Doñana, Spain.
TA User (visit): Irma Wynhoff, De Vlinderstichting - Dutch Butterfly Conservation, The Netherlands (April, 2013).
Project Description: The Mediterranean Basin is suggested as a model region for Global Change research in many aspects, particularly in relation to the importance of changes in the use of natural resources within ecosystems. The exceptional levels of biodiversity in the Mediterranean and the anticipated consequences of its possible reduction justify the high priority given to the issue of interactions between Global Change factors and biodiversity in this region. Such an important problem as Global Change demands concerted political action at the international level. In this context, the role of researchers should be to provide unbiased information on how biological systems react in a changing environment and what this means for the future. What is at stake is not only biodiversity conservation targeted at a species by species level, but the conservation of ecological networks and the processes and services they support, which will ultimately determine the long-term survival of all species.
Climate change is one of the major threats to butterflies in Europe. Butterfly communities react to climate change by changing their composition, where warmth-loving species become more abundant and cool species decline (pdf). In order to conserve butterflies and target scarce resources, it is vital to have data on species distribution and trends from as many important sites from the North to the South and from the West to the East in the whole of Europe. In addition, monitoring data are used for policy relevant indicators, such as the butterfly grassland indicator and the butterfly climate change indicator (pdf). In the Doñana National Park in southern Spain, butterfly monitoring has been conducted since 2005, but integration of these data into the Butterfly Conservation Europe Network has not yet been achieved. At the same time, although contacts have been established, at a national scale butterfly monitoring is conducted mainly in autonomous regions, without a recognized framework for connecting data among regions. With this project, we aim to improve the cohesion of monitoring data collected in Doñana, facilitating its incorporation in national and international frameworks. This will be done in collaboration with the Monitoring team of the Doñana Biological Station (EBD-CSIC) and the main representatives of the existing networks for Butterfly Monitoring in Spain. The ultimate goal will be the supervision of a renewed version of the monitoring protocol of butterflies in Doñana (Spanish and English), identifying the integrative network in which the monitoring work will be conducted in the future. This protocol will be published on the EBD-CSIC website and on the BCE website. Integration of monitoring data from the southernmost regions in Spain into the framework of BCE will extend and improve the butterfly indicators in the future.
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Nitrogen gas emissions from contrasting soil environments (NTRAST).

ExpeER TA Site: Klausenleopoldsdorf, Austria.
TA User (visit): Jesper Christiansen, University of Copenhagen, DENMARK (April, 2013).
Project Description: This project aims to study the interactive effects of soil hydrology and nitrogen (N) availability on emissions of NO, N₂O and N₂ from soils across a wide N deposition gradient from the low northern Greenland (Zackenberg) over pacific Canada (Vancouver Island) to the high central Europe (Klausenleopoldsdorf).
Empirical evidence suggest that increased N availability stimulates NO and N₂O production. However, we raise the question whether increased availability over a natural gradient of reactive N coupled with a wetter soil environment also shifts denitrification towards relatively higher N₂O emissions compared to N₂?
We will pursue to answer our question by incubating intact soil cores sampled from similar soil hydrological gradients for each site at the state-of-the facilities at Federal Research and Training Centre for Forests, Natural Hazards and Landscape (BFW) where we can directly measure the emission of NO, N₂O and N₂ under controlled laboratory conditions as well as CH₄ and CO₂ fluxes. For all soil samples we will also determine central soil chemical attributes, such as extractable N species, pH as well as total organic carbon and nitrogen.
By studying gaseous N emissions across the wide natural N gradient using the system at BFW we will shed new light on how nitrogen availability is related to greenhouse gas emissions from soils ranging from the arctic to temperate ecosystems. Also, we will obtain rare simultaneous estimates of N₂, N₂O and NO emissions from understudied regions of the northern hemisphere that will represent new knowledge in the field as well as be useful input to modeling.

Influence of biodiversity on soil water flow.

ExpeER TA Site: Montpellier Ecotron, France.
TA User (visit): Marcus Guderle, Friedrich-Schiller-University Jena, Germany (February, 2013).
Project Description: Besides comprising an essential resource for plants soil water acts as a transport medium for dissolved matter and mediates microbial activity. Thus soil water fluxes and resulting redistribution of soil water provide important information for understanding, besides resource use strategies, other biological and abiotic processes. Up to know it is not possible to measure soil water flow directly (Vereecken et al., 2008), and our knowledge about changes of ecosystem root water uptake profiles with plant diversity is rudimentary. Soil water fluxes can only be estimated either (i) through inverse modelling or (ii) directly for a large soil column with lysimeters like in the ECOTRON, where with the drainage flux a closed water balance can be recorded. The aim of this research is to investigate (1) whether root water uptake profiles differ significantly between ecosystems of different diversity (2) how plant diversity influence vertical soil water fluxes and redistribution of soil water over the growing season and (3) how plant diversity contributes to groundwater recharge or to what extent they use groundwater for transpiration. Furthermore, we will (4) prepare data for validation of an inverse model, which shall be applied to the original plots in the Jena Experiment. This task can only be achieved with data from a lysimeter, such as the ECOTRON. In order to investigate the questions, we will analyse time series of soil matric potential, soil moisture, groundwater table, drainage, evapotranspiration as well as irrigation recorded in a measurement campaign on 12 lysimeters in the ECOTRON facility from April to August 2012. These lysimeters from the Jena Experiment field site cover two diversity levels (4 and 16 species). We will (1) close the water balance of each of the macrocosms, and (2) apply data-driven methods on lysimeters with different diversities to estimate root water uptake profiles and soil water fluxes based on the short term fluctuations of soil moisture.
The visit in Montpellier is needed to exploit with inputs from the Ecotron personnel who collected the data, the Ecotron data base related to the Ecotron-Jena experiment which was run from March to August 2012. The visit is planned from February 1st to April 5th 2013.
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Measuring and modelling soil CO₂ concentrations, production and diffusion (MMCO₂).

ExpeER TA Site: Hyytiälä, Finland and Hesse, France.
TA User (visit): Markus Herndl, AREC Raumberg-Gumpenstein, Austria (February, 2013).
Project Description: The role of soil CO₂ efflux from ecosystems in the terrestrial carbon cycle and its feedbacks to climate change is well known and there are several scientific efforts to characterize and quantify soil respiration across different environments. For ecosystems such as forests there exist a lot of studies, but comparatively little is known for agricultural systems such as cultivated grassland. In the Expeer project, knowledge regarding measuring and modeling CO₂ efflux across Europe will be bundled and cross-linked. Moreover, the determination of soil CO2 produced in the different horizons by respiration from efflux data needs the measurement of soil CO₂ storage. At the Hesse and Hyytialla sites there are continuous measurements of CO₂ in soil pore space to quantify soil CO₂ storage using Membrane Tube Technique. Also on both sites expertise is consisting about using and developing the soil CO₂ gradient method. The main aim of the of the project MMCO2 is, to acquire site specific knowledge of modeling with the soil CO₂ gradient method and the method of measuring CO₂ in soil pore space. In the course of the project the two site approaches will be compared and the essential regarding technique and scientific methods transferred to grassland based system. The findings of the project will be used to establish a facility to measure and model CO₂ efflux from cultivated grassland in Austria. The expertise exchange can help cross-linking systems and approaches from ecosystem science to application in agricultural sciences.
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ModEling The current and future HOverfly Distribution (METHOD).

ExpeER TA Site: Fruška Gora, Serbia.
TA User (visit): Aggeliki Kaloveloni, University of the Aegean/Geography, Greece (January, 2013).
Project Description: Prediction of species distribution is essential due to the limited knowledge of their current distribution and the vulnerability of most species to a potential climate change. The need for detailed knowledge about species distribution lead to the rapid development of species distribution models (SDMs), which are numerical tools that combine species occurrence data with environmental variables in order to predict distributions across landscapes.
SDMs are particularly useful for pollinator studies. Pollination is a crucial ecosystem service, with great significance for primary production, the reproduction of flowering plants, and the maintenance of organisms that depend on floral resources. Besides bees, hoverflies are especially considered to be very important pollinators worldwide both for wild flowers and crops, as the adults commonly visit flowers and feed on pollen and nectar. Approximately 6000 species have been described and 188 genera have been recognized, but the distribution of most genera, unlike that of most tribes, is notably restricted. Despite their significant role in pollination they haven’t been studied as much as bees. Considering their importance, better knowledge of hoverflies’ spatial distribution would facilitate the estimation of habitat suitability for hoverfly populations and the determination of future sampling locations. Thus, SDMs may be useful tools for the effective ecological protection, management and conservation of species and their habitats.
For the prediction of species distribution regression-based models will be used, such as generalized linear model (GLM), generalized additive model (GAM) and boosted regression trees (BRT), using the R software (R Development Core Team), and the maximum entropy model using the Maxent software. The models will be checked for their accuracy and the correlation of species potential occurrence in relation to environmental variables will be explored. Also, the impact of climate change on species distribution will be predicted for different climate change scenarios and periods.
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Exploration of relationship between vegetation-soil parameters and hyperspectral data (EVAHYPE).

ExpeER TA Site: Negev, Israël.
TA User (visit): Christoph Salbach, Helmholtz Centre Potsdam GFZ, Germany (January, 2013).
Project Description: The objective of the proposed research is to link vegetation and soil variables with hyperspectral data. More specifically, to explore the most sensitive and relevant spectral bands, between the blue (400 nm) and the short wave infrared (2,500 nm), that are related to each of the biophysical variables. In order to fulfill these objectives two statistical methods will be employed: (1) Principle Components Regression (PCR) and Partial Least-Squares Regression (PLSR) methods that are used for soil reflectance spectroscopy, agricultural, and industrial applications, as well as for mass spectrometry metabolic data; and (2) Machine learning methods, such as Random Forest (RF), that pose attractive features for spectroscopic analysis. Parameters from these two methods will be compared for their ability to choose the most important bands out of a high-resolution spectra, robustness against noisy training data, and model validation assessments. The visit to the NEGEV site will enable comparisons and standardization of hyperspectral measurements and allow us to run the statistical models on the obtained spectral measurements. To realize the above objectives, a period of 3 months is planned.
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Phenological and primary production studies by remote sensing (PHESENSENSING).

ExpeER TA Site: Negev, Israël.
TA User (visit): Cornelia Glaesser, Martin Luther University, Institute of Geosciences, GERMANY (November, 2012).
Project Description: The current TA proposed project takes advantage of high-resolution (6.5 m) and high-temporal (a few days revisit time) Rapid-Eye data, which will be available during the 2012-2013 growing season over the NEGEV LTER site (Israel), in order to explore methods for spaceborne assessing of phenological scheme.
The NEGEV LTER is located in a semi-arid region. Natural vegetation in these regions is characterized by three ground features, in addition to bare surfaces – biological soil crusts, annuals, and perennials. It is hypothesized that these three elements have distinguishable phenological cycles that can be detected by spectral ground measurements and by calculating the weighted normalized difference vegetation index (NDVI). The latter is the product of the derived NDVI of each ground feature and its respective areal cover. Each phenological cycle has the same basic elements – oscillation from null (or low) to full photosynthetic status and back to a stage of senescence. However, they vary in phase. The biological soil crusts show the earliest and highest weighted NDVI peak during the rainy season, and their weighted NDVI signal lasts longer than that of the annuals. The annuals are dominant in late winter and early spring while the perennials predominate in late spring and during the summer.
For this project, RapidEye images will be acquired in Germany. A 10-day visit to the NEGEV site will be devoted to initialize the field spectral measurements that will be continued by Prof. Karnieli throughout the season. Spectral and image data will be mutual processed.
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Remote Sensing of Forest Canopy Cover in the Negev LTER with RapidEye (RFCCRapidEye).

ExpeER TA Site: Negev, Israël.
TA User (visit): Ibrahim Ozdemir, Suleyman Demirel University, Isparta, TURKEY (November, 2012).
Project Description: Forest canopy cover, also called crown cover, is described as the proportion of land surface covered by the vertical projection of tree crowns in a definite area. Maps of forest canopy cover are required for a wide range of ecological applications, including assessment of the status of suitable wildlife habitat, determination of fuel and potential fire risks, watershed management, erosion control, monitoring disturbance factors (thinning, illegal logging, insect damages etc.), detection of carbon pools, as well as timber management purposes. Measurement of forest canopy cover based on field measurements and air photographs is too laborious and time consuming to be used in extensive forest inventories. Satellite remote sensing seems to provide a good alternative to these traditional methods to map and monitor canopy cover and its changes over wide geographic regions. The potential use of new satellite systems should be investigated for estimating forest canopy cover. The RapidEye satellite image, with a 5 m spatial resolution and an additional red-edge band, is a cost efficient means for this purpose. Furthermore, in the literature, there is no work employing satellite images with 5 m resolution for estimating forest canopy cover. Therefore, our research goal is to develop and test a remote sensing platform for the prediction of forest canopy cover using vegetation indices derived from RapidEye satellite imagery. The research site will be the Yatir forest, part of the Negev LTER, located within a mature pine forest (Pinus halepensis, Mill) planted in a semi-arid zone. Multispectral remote sensing data from RapidEye sensor will be acquired. This recently launched satellite records radiance in five broad bands corresponding to the blue, green, red, red-edge and near-infrared (NIR) part of the electromagnetic spectrum. A set of 60 plots with the size of 2500 m² will be designed, both in the aerial photos and in the satellite data. Forest canopy cover will be determined manually on the aerial photographs and then the corresponding vegetation indices will be calculated for each sample plot. We will assess the relationships between the vegetation indices (Normalized vegetation index, NDVI; soil adjusted vegetation index, SAVI; linear four point interpolation approach, REIP) and the forest canopy cover by simple and multiple linear regression analysis. 40 sample plots will be used for model fitting, and the remainder (n = 20) will be used for model validation. The expected research results are; 1) We will determine the vegetation indices that are the most correlated with forest canopy cover. 2) We will develop an approach to reduce the effect of understory vegetation on spectral values of the satellite data in calculating the vegetation indices. 3) We will generate a model for predicting and mapping the canopy cover, which might be used to monitor the changes on the forest canopy cover.
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Response of fine roots to soil warming.

ExpeER TA Site: Achenkirch, Austria.
TA User (visit): Werner Borken, University of Bayreuth, GERMANY (October, 2012).
Project Description: Effects of soil warming on fine root turnover in a spruce-beech forest. Turnover and mortality of fine roots may be enhanced in the warming plots while the stock of fine root biomass may be not affected. In the short-term, most warming studies suggest increasing turnover rates and mortality of fine roots, but the results are often somewhat contradicting because of applied methods or interacting factors like the availability of inorganic N. Our knowledge on the long-term adaptation of fine root systems of Norway spruce and European beech to soil warming is scarce.
Seasonal patterns of fine root biomass and necromass, as well as fine root turnover, will be assessed by a combination of sequential coring and in-growth cores in the organic layer and top mineral soil. Additionally, the age of live fine roots will be measured using the radiocarbon signature of structural C components. These measures will provide information about the longevity of fine roots in different soil horizons under elevated soil temperature.

Using Syrphidae (Diptera) as bioindicators (USB).

ExpeER TA Site: Fruška Gora, Serbia.
TA User (visit): Antonio Ricarte-Sabater, National Museums Scotland, SCOTLAND (September, 2012).
Project Description: Hoverflies (Syrphidae) are one of the most diverse and best known Diptera families in Europe. However, their biology and ecological interactions are still insufficiently understood. They live in almost all habitat types and exploit a variety of resources in the ecosystem. Adult hoverflies feed on pollen and nectar of various plants and larvae feed on rotting-associated bacteria and detritus, live-vegetal tissues and other insects. Hoverflies have been used as bioindicators, for instance, when assessing the conservation status of habitats. The main target hoverflies of this study are those with saproxylic and phytophagous larvae. Saproxylics are dependent on dead wood or decaying material associated with trees, thus they are good bioindicators in forest ecosystems. Due to their dependence on microhabitats containing water/moisture (e.g. tree holes), saproxylics have been proposed as indicators of Climate Change. The biology of many saproxylic hoverflies is unknown, including species protected in Serbia by legislation. There is an even bigger gap in the knowledge of the biology of hoverflies feeding on underground parts of geophytes. In Serbia, Fruška Gora National Park offers an excellent framework to study the ecological interactions of both saproxylic and phytophagous hoverflies. This is because all the major vegetation types (woodland, scrubland and grassland) are represented in the park and the diversity of saproxylic and phytophagous hoverflies is high (49 species in total). By improving our knowledge of the park hoverflies, we will make them more effective bioindicators. Different breeding sites in trees and geophytes at each of the three research localities in Fruška Gora will be searched for immature stages in this initial study. An inventory of the species found in the site, based both on adults and larvae, will provide additional data on species distribution, habitat preference, etc. The expertise of the syrphidologist team at the University of Novi Sad and the environmental information available from each of the research localities will support and facilitate the interpretation of the obtained results, which will also be of potential use by the park authorities.
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Determination of the biological soil quality of biochar fields

ExpeER TA Site: Beano, Italy.
TA User (visit): Nele Ameloot, Ghent University, BELGIUM (September, 2012).
Project Description: In Europe several field studies have been set-up to measure the effect of biochar on plant productivity, nutrient dynamics, C sequestration and SOM dynamics, while the soil biological quality of these fields sites has rarely been sampled. We think this is a major knowledge gap, since soil biological parameters are essential to understand the mechanisms underlying the potential of biochar to sequester C, change nutrient dynamics and increase yields.
The objectives of this study are to sample several biochar fields throughout Europe and measure the biological soil quality of these fields. By sampling several fields (including the Beano field sites in Italy), amended with a wide variety of biochar types at different of application rates, established in different soils and with different establishment times, we could infer the effect of biochar on soil biological quality.

Isoprene emissions and pigment content in Sphagna from peatlands (ICARO)

ExpeER TA Site: Whim, UK.
TA User (visit): Carlos Raul Ochoa Hueso, Rey Juan Carlos University, SPAIN (August, 2012).
Project Description: Anthropogenic reactive nitrogen (N) deposition can be detrimental to the sustainability and functioning of semi-natural terrestrial ecosystems across the globe. Ombrotrophic peatlands, dominated by mosses such as Sphagnum spp. represent major carbon (C) reserves, which play a very important role in mitigating the effects of climate change through C storage, a consequence of decomposition rates being slower than rates of C fixation. Increasing the N availability in such ecosystems can compromise their ability to store C. For example, it has been demonstrated that increased N deposition can reduce the phenol content in peatland mosses, accelerating litter decomposition and, therefore, reducing C sequestration. Increased N deposition can also increase photosynthetic and photoprotective pigment content in mosses, including chlorophylls and carotenoids. Carotenoids are photoprotective pigments made of isoprene monomers. The early stages of the carotenoid biosynthesis pathway also lead to the synthesis of isoprene in some plant species, including Sphagnum spp. When emitted to the atmosphere, isoprene can significantly contribute to the net C balance between a given ecosystem and the atmosphere and also interact with the local climate. In this context, we are interested in analyzing the pigment content (including carotenoids) of Sphagna in relation to isoprene emissions at Whim, an ombrotrophic peatland in the UK, where realistic doses of simulated N deposition are being regularly applied. Currently Dr. Lucy Sheppard’s group is measuring isoprene emissions (Dr Sue Owen) at Whim but have no facilities (HPLC) to look at different pigments. It will be complementary to measure the pigment content in Sphagnum species present at the field site to see if the variations in isoprene emissions and C balance can be partially related to changes in Sphagna pigment content. The plan would be to visit Whim for one week to do the field survey and then bring the samples back to my lab in Spain to run the samples with HPLC. This project would be highly beneficial for me as young scientist and for the group of Dr. Lucy Sheppard given that the measurements I am planning to do at Whim totally complement their research.
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Ground and space measurements and modeling of soil albedo (GaSMoSAN).

ExpeER TA Site: Negev, Israël.
TA User (visit): Jerzy Cierniewski, Adam Mickiwicz University, Poznan, POLAND (August, 2012).
Project Description: Energy exchange at the ecosystem scale is primarily influenced by surface albedo. Therefore, albedo can have substantial effects on climate. Strong links were evidenced between surface albedo and biodiversity, phenology, carbon sequestration, and more. The aim of the project is to explore the diurnal variation in broadband blue-sky albedo of bare soils in semi-arid ecosystems (Negev-LTER). Data sets, measured from ground level under clear sky conditions at minute intervals, enable us to find quantitative relations between data and the solar zenith angle for different desert surfaces with respect to their roughness. Our experience in measuring and modelling of soil surface bidirectional reflectance and albedo, which has been accomplished so far in the Negev, allows us to suppose that these relations can be clearly specific and different for smooth and rough surfaces. The relations will enable us to predict instantaneous albedo values of the surfaces at a chosen latitude during any day of the year. We expect that results of this study will allow us to predict the optimal local solar time when instantaneous soil albedo of those surfaces reaches their average diurnal value. The optimal time for this average albedo observation with an accepted error will be considered in context of its achievement by satellite radiometers on sun-synchronous orbits. The average diurnal surface albedo seems to be helpful as a basis for studies of environmental processes associated with the energy transfer between soil, vegetation and atmosphere. Soil albedo will be measured by albedometers within a spectral range of 335-2800 nm using data loggers, and the soil surface roughness will be recorded with stereo-photographs technology.
Output: Effects of Soil Surface Irregularities on the Diurnal Variation of Soil Broadband Blue-Sky Albedo (Article in press). Cierniewski, J., Karnieli, A., Kazmierowski, C., Krolewicz, S., Piekarczyk, J., Lewinska, K., Goldberg, A., Wesolowski, R., Orzechowski, M.
Abstract: This paper quantitatively explores, in terms of roughness indices, the effect of soil surface irregularities on the diurnal variation of the broadband blue-sky albedo of a large range of soil properties. Field studies were carried out on cultivated and uncultivated soil surfaces in Poland and Israel that vary in roughness and brightness. It was found that these irregularities, formed by different agricultural equipment and modified by rain or sprinkler irrigation, can be quantified by two roughness indices. Soil roughness not only affects the overall level of the diurnal variation of the albedo, but also affects the intensity of the diurnal increase from the solar zenith angle [Formula: see text] at the local noon to about 75° - 80°. The roughness indices are variables that precisely determine only the albedo at the local solar noon of soils with the same color value. If the contents of soil organic carbon (SOC) and calcium carbonate are treated as the dominant variables, combined with one of the indices, these three variables together would significantly describe the albedo at the local solar noon of all soil surfaces. The soils, with their high irregularities, showed almost no rising values of albedo at a [Formula: see text] lower than 75 °, while the smooth soil surfaces exhibited a gradual increase of the albedo at these angles. It is concluded that the roughness indices provide sufficient means to accurately describe the diurnal variation of the albedo of a wide range of surfaces, disregarding other soil properties.
ISSN: 19391404Source Type: Journal Original language: English
DOI: 10.1109/JSTARS.2014.2330691 - Document Type: Article in Press
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FLUxes of greenhouse gases from tree STems and the influence of TREE species composition (FLUSTTREE).

ExpeER TA Site: Höglwald Forest, Germany.
TA User (visit): Agustin Rubio, Universidad Politécnica de Madrid, SPAIN (June, 2012).
Project Description: The main objective of the project is to investigate stem GHG (main focus on N₂O but also CH₄) emissions in the managed Höglwald forest on beech (Fagus sylvatica) stands of different ages: 1-3 year: 15 years, 100 years.
We will take advantage of the intensive investigation in relation to soil-atmosphere GHG exchanges which has been taking place at the experimental site since approximately 15 years. Therefore, a particular focus will be given to the links between soil and stem GHG exchange and underlying processes. We hypothesize that higher GHG concentrations in the soil atmosphere will lead to higher GHG emissions by both soils and plants. That would mean that, in situations when high GHG emissions from the soil are measured - by conventional soil chambers -, total ecosystem fluxes might still be underestimated, if stem emissions are not taken into account.
Given that the assumed mechanism of the GHG emissions from stems is thought to be: (1) dilution in soil water, (2) uptake of soil water by the roots and transportation through the phloem (3) release by diffusion and transpiration, we hypothesize that the release of GHG from plant stems will decrease with increasing height of the plant organ or plant part. Finally, since photosynthetic activity determines nutrient flow across organ parts, we hypothesize that light will play a role in the N₂O and CH₄ emissions, being higher during day which may could cause a lack time between soil and plant emissions.
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Long-term effects of Nitrogen deposition in lichen ecophysiology.

ExpeER TA Site: Whim, UK.
TA User (visit): Silvana Munzi, University of Lisbon, PORTUGAL (June, 2012).
Project Description:The excess of reactive forms of nitrogen (N) from anthropogenic sources in the environment has been shown to have dramatic consequences for the structure and functioning of ecosystems and recently claimed to be at a global scale. Lichens are among the most sensitive communities to N pollution at the ecosystem level and several studies have investigated the relationships between lichens and N. However, the ecophysiological long-term consequences of the exposure of both sensitive and tolerant lichen species to N are not completely understood. The Whim Bog, with N manipulation experiment, which has been providing wet and dry deposition to ombrotrophic bog vegetation containing the matt forming lichen Cladonia portentosa, offers the potential to study both long term and short term effects.
We intend to answer the following questions:
1) What are the ecophysiological differences between long-term and short-term lichens exposed to N? We will approach this question by putting lichen transplants next to long-term exposed ones and make a series of ecophysiological performance tests in samples exposed for different periods: 1, 3, 6, 12 months and > 9 years. This will entail an initial visit to the site to set up the transplants and remove samples while the site operators will send us subsequent samples.
Some information derived from short-term laboratory studies have shown that intracellular K concentration might alleviate the N toxicity symptoms in some tolerant lichens. Moreover, other observations at the Whim site have shown that lichens tolerate more N when they are simultaneously exposed to K and/or P. Thus, another question will be:
2) Are K and/or P alleviating the N toxicity symptoms? For this, we will investigate the ecophsyiological performance of lichens (in situ lichens, growing on board walks, and/or lichen transplants) exposed to similar N concentrations but with an external supply of potential alleviators (K and P).
The ecophysiological performance will be measured by evaluating: the Fv/Fm ratio, N location by sequential elution, intra- and extra-cellular K and P and other parameters that will be found to be relevant during the study.
Expected outputs are scientific papers involving both the teams from Portugal and UK.
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Output: Proceedings of the annual congress of the Italian Lichen Society, published on the Notiziario della Società Lichenologica Italiana, ISSN: 1121-9165 (page 53).
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Linking soil organic carbon pools with measured fractions

ExpeER TA Site: Rothamsted, UK.
TA User (visit): Michael Herbst (May, 2012).
Project Description: Soil organic carbon pools play an important role for the understanding and the predictive modelling of heterotrophic respiration. One of the major issues concerning model carbon pools is their purely conceptual definition. They are just defined by a turnover rate. Despite some attempts to link the conceptual model pools to measurable SOC fractions, this challenge basically remains unsolved. In this study we introduce an empirical approach to link the model pools of RothC with measured particulate organic matter fractions and an inert carbon fraction.
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Spruce seedling recruitment (SpruSeR)

ExpeER TA Site: Tatra Windstorm, Slovakia.
TA User (visit): Martin Weiser, University Of Prague, CZECH REPUBLIC (May, 2012).
Project Description: We wish to assess the probability of survival and fitness of spruce seedlings in different microhabitats defined by the presence of dead wood and vegetation on different spatial scales. We propose to establish ca. 150 permanent plots, 3 sq. meters each. In each of these, make a phytosociological relevé in it, measure its orientation and exposition, indicate the amount and form of dead wood. All of the spruce seedlings will be tagged and their height, basal diameter, age and indications of herbivory will be measured. Around each of the seedlings, small and very small phytosociological relevés (900 sq. cm, 225 sq. cm) will be taken. This system will allow us to observe the role of vegetation on vital characteristics of spruce seedling on different spatial scales. Tagging will allow us to link these data with the demography of seedlings.
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Characterisation of organo-mineral associations in soil by NanoSIMS

ExpeER TA Site: Moor House, UK.
TA User (visit): Thilo Rennert, TU München, GERMANY (April, 2012).
Project Description: Lasting water saturation in soil may induce depletion of oxygen and subsequent microbial reduction of Mn and Fe oxides. Re-aeration leads to precipitation of new Mn and Fe phases, which are known to be effective sorbents of organic matter by superficial adsorption and/or co-precipitation. These processes result in the formation of complex biogeochemical interfaces, the composition and architecture of which are still largely unknown. Therefore, we plan to study organo-mineral associations formed in situ in soil horizons with fluctuating reducing and oxidizing conditions. For sample collection, glass wafers will be placed in soil horizons with a fluctuating water table to remain there for a period of water saturation (reduction) and subsequent re-aeration (oxidation) (approx. 6 months). After removal from soil, freshly precipitated organo-mineral associations settled on the wafer surface are to be studied by NanoSIMS, a technique which we also offer to the ExpeER network. NanoSIMS allows for the simultaneous analysis of up to 7 seven ion species released from the sample surface after bombardment by a primary ion beam. Given the sensitivity in the ppm range and a lateral resolution of down to 50 nm, the chemical characterization of small particles on the nano-scale is possible. Further information on the architecture of micro-aggregates of the particles can be obtained by analyzing thin sections produced from micro-aggregates embedded in resin. A prerequisite for our study is information on water-table fluctuations and soil-solution composition (redox indicators such as Fe(II) and nitrate). We therefore strongly rely on a well monitored field site on hydromorphic soils. We plan to carry out the study at a site of the ExpeER program operated by the Centre for Ecology & Hydrology in Lancaster, UK (“Moor House”), where these data are monitored.

Biodiversity and ecology of forest-associated Diptera (BEFAD)

ExpeER TA Site: Fruška Gora, Serbia.
TA User (visit): Gunilla Stahls, Finnish Museum of Natural History, University of Helsinki, FINLAND (March, 2012).
Project Description: Fungivorous Diptera constitute a major biodiversity component of deciduous forests utilizing the moist wood and habitats provided by mushrooms and softer polypores, impacting the structure and function of the forest ecosystem. This study will focus on the inventory and documentation of the component of particular forest-associated Diptera in the three research localities within the Fruska Gora National Park, Serbia. The target group for study is a key group of forest-associated flies, the Platypezidae, that are highly dependent on deciduous forests with high humidity and a sufficient proportion of decaying wood as substrate for various fungi in which the larvae develop. The main goal of the project is to achieve an in-depth understanding of the species diversity and ecological interactions between these two dead-wood dependent organisms, the insects and their host fungi. The proposed project will advance knowledge on the habitat preferences (humidity, amount of decaying wood, and other parameters) and distributions of the target insect group and their host fungi. Previous studies have not considered these fungal groups and their associated insects in Fruska Gora National Park, and thus this study fills a gap in the knowledge, and is of potential use for local nature protection agencies.

Carbon and water relations of grassland ecosystems at Park Grass.

ExpeER TA Site: Rothamsted, UK.
TA User (visit): Hans Schnyder, TU München, GERMANY (February, 2012).
Project Description: Carbon uptake and water loss of plants are controlled by the regulation of carbon assimilation rate (A) and stomatal conductance (gs). Any changes in these parameters under rising atmospheric CO₂ influence plant water-use efficiency and can affect global carbon and water cycles. Thus, a better understanding of the A and gs response by plants to rising atmospheric CO₂ in terrestrial ecosystems is important to help predict future atmospheric CO₂ levels and the consequences for climate change. Long-term responses of plants to rising CO₂ during the last century can be studied retrospectively by means of stable isotope analysis. Such studies have been successfully conducted on trees, but little is known about herbaceous vegetation, due to the lack of appropriate samples. The short-term CO₂ response of A and gs has been shown to depend on the availability of nutrients and on the responsiveness of different plant functional groups. The Park Grass Experiment (PGE) is a unique resource to test this response at the long-term ecosystem level. The PGE comprises various fertilizer treatments with different amounts of nitrogen, phosphorus and potassium on old, established semi-natural grassland. Archived hay and herbage samples are available for each year and every fertilizer treatment since establishment of the experiment in 1856. We have already analyzed stable carbon isotope discrimination (13Δ) of vegetation samples from the control plot 3d and have shown that intrinsic water-use efficiency (Wi) of nutrient-poor temperate grasslands has indeed increased since 1857 (Köhler et al. 2010). Recently, more herbage samples were analyzed to determine whether the long-term trends in Wi differed between grassland plant communities with different nutrient supply (Köhler et al. 2012, in preparation). Now, we would like to analyze herbage from treatments which have received ammonium sulphate fertilizer, to verify if ecosystems receiving NO^3- or NH⁴⁺ fertilizers differ in their Wi response (treatments with sodium nitrate have already been sampled). As it is possible that soil pH effects (e.g. via its effect on botanical composition) may interact with nutrient effects, we propose to analyze herbage from subplots with differing soil pH to compare changes in 13Δ within each fertilizer treatment.

Hydraulic parameterization for MuSICA.

ExpeER TA Site: Pierroton, France.
TA User (visit): Tamir Klein, The Weizmann Institute of Science, Rehovot, ISRAEL (October, 2011).
Project Description: The aim of the project is to integrate hydraulic parameters governing the timing and magnitude of forest hydrological fluxes into MuSICA, a multilayer, multileaf pine forest model. Hydraulic parameters include: (1) transpirable water content, at specific soil depths; (2) xylem sensitivity to embolism, from measurements of hydraulic conductivity in twigs; (3) disequilibrium between leaf transpiration and xylem sap flow; and (4) leaf water content changes.
The above parameters will be integrated into the parameterization phase of the MuSICA model, in scales ranging from diurnal to seasonal.
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Detection of shoot/root markers in SOM after land use change (MARK).

ExpeER TA Site: Grignon, France.
TA User (visit): Cecilia Marià Armas Herrera, Universidad de La Laguna, Tenerife, SPAIN (October, 2011).
Project Description: Cutins and suberins are aliphatic plant biopolyesters that are among the most recalcitrant plant molecular structures in soils and contribute to enrich the stable pool of SOM. Cutins of plant shoots, and suberins, mostly present in roots, may act as potential biomarkers for aboveground and belowground biomass of non-woody plants. The biomarker potential of these plant compounds resides in their characteristic compositions in different plant tissues, which may be used for tracing them in soils and sediments by means of stable 13C isotope labelling.
The overall aim for this work is to study the composition of cutins and suberins in below and above-ground biomass of grassland and farmland, and to follow the fate of the root and shoot biomarkers in soils over the conversion of grassland to farmland.
The contribution of cutins and suberins to SOM will be studied by identifying and quantifying their constitutive monomers. The isotopic signatures of cutin and suberin monomers will be used to evaluate the turnover of SOM and the specific dynamics of root vs. shoot tissues in soils.
The study will take place at the laboratory of Biogeochemistry and Ecology of the Earth Surface (BIOEMCO) in Thiverval-Grignon, France. The proposed work is part of a broader research framework, focused on the dynamics of SOM after land use change and the contributions of roots and shoots of plants to SOM.

Nematodes the molecular way (NEMACULE).

ExpeER TA Site: Jena, Germany.
TA User (visit): Gerlinde De Deyn, Wageningen University, THE NETHERLANDS (October, 2011).
Project Description: In our project 'Nematodes the molecular way'(NEMACULE) we propose to apply cutting edge techniques for the detection, identification and quantification of soil dwelling nematodes. Specifically we propose to use molecular bar-coding to investigate the abundance and identity of entomopathogenic nematodes in the Jena biodiversity experiment. These nematodes are of particular functional importance because they kill herbivorous insects so that they can provide indirect protection to plants. The great advantage of this novel technique is that key species of nematodes can be detected in large samples of nematode communities because subsampling is not needed (in contrast to morphological analysis). Entomopathogenic nematodes are such key species as they can have large impacts on insect communities despite representing a small fraction of the total soil nematode communities at field scale.
We propose to collect soil samples across the plant species richness gradient in the Jena field experiment. From these we will extract the nematodes and determine the composition of the entomopathogenic nematodes (species and abundance) using DNA bar-coding. Our results will complement the data on insect communities and plant productivity, thereby contributing to the mechanistic understanding of the coupling between biodiversity and ecosystem functioning. Moreover, our project will be one of the first that uses cutting edge techniques for studying nematode communities in the wild. The method is already well established but has not yet been used in the context of biodiversity-ecosystem functioning studies. If our application is successful our study will generate much interest in applying our technique in other studies, for example in other ExpeER sites.

Water Limitation of Canopy and Understorey in a maritime pine forest.

ExpeER TA Site: Pierroton, France.
TA User (visit): Tino Rau, Helmholtz Centre for Environmental Research UFZ, Dept. Of Computational Hydrosystems (CHS), GERMANY (September, 2011).
Project Description: The aim of the study is to analyze differences in water limitation between understorey and overstorey of a maritime pine stand.
Motivation: Low soil water content leads to a decrease in Gross Primary Production (GPP). This water stress can be characterized by a threshold value of Plant Available soil Water (PAWt). Soil moisture below PAWt leads to a reduction in GPP. PAWt can vary widely but a rather constant value of around 0.4 has been reported for a broad variety of European forest ecosystems. However, isohydric and anisohydric plants have different water use strategies and should therefore show different thresholds. We will examine water limitation of overstorey and understorey vegetation in a maritime pine stand at Le Bray/France, the precursor site of ECOSYLVE, since the understorey consists of isohydric grasses and overstorey of anisohydric trees.
Method: Latent heat (lE) and Net Ecosystem Exchange (NEE) will be measured at two 7m and 40m high towers with eddy covariance. Additionally soil moisture (Θ) will be measured throughout the root zone. The measurements will be combined together with simulations of the SVAT-scheme MuSICA of INRA-Epiphyse to understand water stress of over- and understorey in the maritime pine stand.

Extreme event effects on grassland soil respiration.

ExpeER TA Site: Montpellier Ecotron, France.
TA User (visit): Angela Augusti, CNR IBAF, Porano, ITALY (September, 2011).
Project Description: Extreme events (e.g. heat waves and severe summer drought), are forecasted to be more frequent in the coming future. Moreover, it is interesting to study the effects of extremes events in a future climate context, meaning warmer and drier conditions than present, and with an increased atmospheric CO₂ concentration. The responses of terrestrial ecosystems to such extreme events will clarify, among the other things, the role of biosphere as sink for atmospheric CO₂.
The total size of terrestrial soil organic carbon, 1m depth, has been estimated to be 1500 Pg of C, with a potential global rate of soil C sequestration between 68 and 80 Pg/year. This depends on several factors that act on the equilibrium between ecosystem photosynthesis and respiration, among which include climate factors such as temperature, precipitation and atmospheric CO₂ concentration.
In particular, my interest is focused on the combined effects of such climate factors on CO₂ efflux from soil as a result of autotrophic and heterotrophic respiration. To disentangle the different components of CO₂ soil efflux my approach involves separate analysis of total soil, heterotrophic and root respiration.
At the ECOTRON of Montpellier, there are portions of mid-altitude grassland, originating from central France, which are exposed to a future climate scenario reproducing air temperature and precipitation for the period 2040-2060 (air temperature 2.3 °C higher and precipitation 11% lower than current climate). Out of the 12 macrocosms present at the ECOTRON, 6 are exposed to ambient CO₂ and 6 to a CO₂ concentration of 520 ppm. During summer, a heat wave and a drought stress will be applied. During this period, air temperature will be increased by 3.5 °C, compared to the temperature predicted for the period 2040-2060; at the same time a drought stress (0 mm precipitation) will also be applied.
Results from this experiment will shed light on the potentially positive effect of increasing atmospheric CO₂ concentration on the effect of drought stress on soil respiration. In other words, results will contribute to clarifying the role grassland ecosystems will have on C sequestration in the coming years.

Remote sensing of surface fluxes (Fluxres).

ExpeER TA Site: Doñana, Spain.
TA User (visit): Monica Garcia Garcia, University of Copenhagen, DENMARK (September, 2011).
Project Description: This proposal is focused within a broader framework to improve our understanding of the variability in energy fluxes in Mediterranean ecosystems.
We aim to provide spatial estimates of water and carbon fluxes from different ecosystems in the Doñana National park and compare them with some of the available field instrumentation.
The ExpeER program will facilitate the collaboration between the University of Copenhagen, the Conservation Biology group and the ICTS from the Estacion Biologica de Doñana (CSIC). We plan to have a week of field work at Doñana to (i) set up four sap flow sensors in the shrublands ecosystem, and (ii) measure LAI (Leaf Area Index) transects at the shrublands ecosystems using a LAI-2000 (Licor instruments). The LAI measurements are necessary to calculate the total plant transpiration from the sap-flow information. We will also compare the measured LAI with the fraction of solar intercepted radiation from pyranometers, to explore the possibilities of measuring LAI and fPAR (Fraction of Absorbed Phothosyntethetic Active Radiation) in a continuous fashion, as we have pyranometers located above- and below canopy at the shrubland site.
We will also organize the experimental design for performing future scintillometer measurements, in collaboration with the University of Copenhagen, over the shrublands and wetlands during fall and spring. The objective is to measure the sensible heat flux with the scintillometer, which allows evapotranspiration to be estimated at the shrublands and wetlands, where eddy covariance data are not available yet.

CASTELTOF

ExpeER TA Site: Roma-Lecceto, Italy.
TA User (visit): Daniel Hauser, University of Innsbruck, AUSTRIA (August, 2011).
Project Description: The modified PTR-MS developed at the University of Innsbruck (2010/11) provides ultra-fast response times, especially for sticky compounds i.e. like ammonia, due to high flow and high temperature. These new features, in contrast to the conventional PTR-Quad/TOF-MS techniques, in combination with switchable primary ions are decisive factors for online measurements at field sites.
For the CASTELPORZIANO field campaign 2011 we will use the O²⁺-Mode to ensure the maximal detection efficiency of Ethylene, Ammonia and Carbonyl sulfide (COS). Moreover, it might be possible to measure Ethylene, Ammonia and COS fluxes.
The three compounds mentioned above could be responsible for various interaction mechanisms between the atmosphere and biosphere. Therefore our modified PTR-MS allocates the required ultra-fast response times and ultra-high sensitivities to ensure precise concentration and flux measurements in the field for the first time.

Land Use Change (LUC) Beano.

ExpeER TA Site: Beano, Italy.
TA User (visit): Christopher Poeplau, vTI Institute for Agricultural Climate Research, GERMANY (May, 2011).
Project Description: The main scientific issue addressed in the project is the interaction of biosphere and atmosphere (gas exchange) in the context of greenhouse gas fluxes as influenced by land use and land use change. Land-use change has a major impact on soil organic carbon stocks. The conversion from e.g. grassland or forest to cropland causes a loss of soil organic carbon and is therefore a source of atmospheric CO₂. Land use change has a major impact on the carbon balance of the soil and is responsible for 20 % of the human induced CO₂ emissions worldwide. The influence of climate and soil conditions, as well as the processes involved in the decomposition of soil organic matter (especially in deeper soil layers), are not yet sufficiently understood. In the past decades, a lot of work has been done on land use change and the influence on soil carbon. However, many open questions concerning the dynamics of soil organic carbon (SOC) still remain. As an important part of a European field campaign, we want to sample different soils in Beano.