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The aim of P2 within the Research Unit 'The Forgotten Part of Carbon Cycling: Organic Matter Storage and Turnover in Subsoils (SUBSOM)' is to contribute to the understanding of the different sources and stabilization processes of subsoil organic matter. This will be achieved by the analysis of the soil organic matter composition in topsoil versus subsoil by 13C NMR spectroscopy in bulk soils as well as organo-mineral associations. This will be done on a number of soil profiles differing in parent material and mineralogy and therefore also in the relevance of organo-mineral associations for subsoil C stabilization. In addition, a specific sampling approach will allow to differentiate three zones associated with the dominating effect of (1) leaching of DOC (the 'bulk soil' between trees), (2) root litter decomposition (the 'root-affected zone'), and (3) direct rhizodeposition of root exudates (the 'rhizosphere' sensu strictu). The contribution of above-ground versus below-ground litter is differentiated by the analysis of cutin and suberin biomarkers. Organic matter derived from microbial sources will be identified by the microbial signature of polysaccharides in the subsoil through the analysis of neutral sugars and amino sugars. Organo-mineral associations will be further characterized by N2-BET analyses to delineate the coverage of the mineral phase with organic matter. With these analyses and our specific analytical expertise at the submicron scale (nanoSIMS) we will participate in selected joint experiments of the research unit.
Farm structures are often characterized by regional heterogeneity, agglomeration effects, sub-optimal farm sizes and income disparities. The main objective of this study is to analyze whether this is a result of path dependent structural change, what the determinants of path dependence are, and how it may be overcome. The focus is on the German dairy sector which has been highly regulated and subsidized in the past and faces severe structural deficits. The future of this sector in the process of an ongoing liberalization will be analyzed by applying theoretical concepts of path dependence and path breaking. In these regards, key issues are the actual situation, technological and market trends as well as agricultural policies. The methodology will be based on a participative use of the agent-based model AgriPoliS and participatory laboratory experiments. On the one hand, AgriPoliS will be tested as a tool for stakeholder oriented analysis of mechanisms, trends and policy effects. This part aims to analyze whether and how path dependence of structural change can be overcome on a sector level. In a second part, AgriPoliS will be extended such that human players (farmers, students) can take over the role of agents in the model. This part aims to compare human agents with computer agents in order to overcome single farm path dependence.
To predict ecosystem reactions to elevated atmospheric CO2 (eCO2) it is essential to understandthe interactions between plant carbon input, microbial community composition and activity and associated nutrient dynamics. Long-term observations (greater than 13 years) within the Giessen Free Air Carbon dioxide Enrichment (Giessen FACE) study on permanent grassland showed next to an enhanced biomass production an unexpected strong positive feedback effect on ecosystem respiration and nitrous oxide (N2O) production. The overall goal of this study is to understand the long-term effects of eCO2 and carbon input on microbial community composition and activity as well as the associated nitrogen dynamics, N2O production and plant N uptake in the Giessen FACE study on permanent grassland. A combination of 13CO2 pulse labelling with 15N tracing of 15NH4+ and 15NO3- will be carried out in situ. Different fractions of soil organic matter (recalcitrant, labile SOM) and the various mineral N pools in the soil (NH4+, NO3-, NO2-), gross N transformation rates, pool size dependent N2O and N2 emissions as well as N species dependent plant N uptake rates and the origin of the CO2 respiration will be quantified. Microbial analyses will include exploring changes in the composition of microbial communities involved in the turnover of NH4+, NO3-, N2O and N2, i.e. ammonia oxidizing, denitrifying, and microbial communities involved in dissimilatory nitrate reduction to ammonia (DNRA). Stable Isotope Probing (SIP) and mRNA based analyses will be employed to comparably evaluate the long-term effects of eCO2 on the structure and abundance of these communities, while transcripts of these genes will be used to target the fractions of the communities which actively contribute to N transformations.
Although global pesticide use increases steadily, our field-data based knowledge regarding exposure of non-target ecosystems is very restricted. Consequently, this meta-analysis will for the first time evaluate the worldwide available peer-reviewed information on agricultural insecticide concentrations in surface water or sediment and test the following two hypotheses: I) Insecticide concentrations in the field largely exceed regulatory threshold levels and II) Additional factors important for threshold level exceedances can be quantified using retrospective meta-analysis. A feasibility study using a restricted dataset (n = 377) suggested the significance of the expected results, i.e. an threshold level exceedance rate of more than 50Prozent of the detected concentrations. Subsequent to a comprehensive database search in the peer-reviewed literature of the past 60 years, analysis of covariance with the relevant threshold level exceedance as the continuous dependent variable (about 10,000 cases) will be performed and the impact of significant predictor variables will be quantified. Parameters not yet considered in pesticide exposure assessment will be included as independent variables, such as compound class, environmental regulatory quality, and sampling design. The simultaneous presence of several insecticide compounds as a well as their metabolites will also be considered in the evaluation. The present approach may provide an innovative and integrated view on the potential environmental side effects of global high-intensity agriculture and in particular of pesticides use.
Research question: Agri-environment schemes play an increasingly important role in European CAP (Common Agricultural Policy) to support biodiversity and environment in agricultural landscapes. They have been implemented since 1992 and now cost a yearly 1.7 billion Euro. Still, there is no conclusive evidence that these schemes actually do contribute to the conservation of particularly biodiversity. The primary objective of this project is to evaluate the (cost-) effectiveness of European agri-environment schemes in protecting biodiversity and to determine the primary processes that determine their effectiveness. This project furthermore aims to determine how CAP may be introduced in candidate EU-members without unacceptable loss of biodiversity. It will provide simple guidelines how researchers, governmental authorities may efficiently evaluate agri-environmental measures. Aim: Agri-environment schemes have been used to protect biodiversity and environment in agricultural areas since 1992. Their effectiveness has never been reliably evaluated. This project aims to evaluate the (cost-)effectiveness of agri-environment schemes with respect to biodiversity conservation in five European countries. It will determine the proper scales that have to be addressed for conservation efforts for a range of species groups. It will determine the most important environmental factors that influence the effectiveness of the schemes. Based on this, recommendations will be made how the effectiveness of schemes may be improved and simple guidelines will be produced how ecological effects of agri-environment schemes can be evaluated efficiently by governmental authorities or other institutions. The ecological effects of the introduction of CAP in a candidate EU-member will be investigated to reduce negative side effects of anticipated land-use changes Scientific methods: We will examine the effectiveness of agri-environment schemes by surveying pairs of fields: a field with an agri-environment scheme and a nearby field that is conventionally managed. In five countries, in each country in three areas, and in each area on seven pairs of fields the species richness of birds, plants and three insect groups (pollinators, herbivores, predators) will be determined. Effects of schemes on pollination efficiency and pest control will be examined using indicator communities. Correlative studies will examine the effects of landscape structure, land-use intensity and species pool on the effectiveness of agri-environmental measures. The spatial scale that is relevant to nature conservation efforts will be investigated via the spatial distribution of species groups. The results will be used to formulate recommendations how to improve the effectiveness of agri-environment schemes and to construct a set of simple guidelines how schemes can be evaluated efficiently yet reliably.
Durum wheat is mainly grown as a summer crop. An introduction of a winter form failed until now due to the difficulty to combine winter hardiness with required process quality. Winter hardiness is a complex trait, but in most regions the frost tolerance is decisive. Thereby a major QTL, which was found in T. monococcum, T.aestivum, H. vulgare and S.cereale on chromosome 5, seems especially important. With genotyping by sequencing it is now possible to make association mapping based on very high dense marker maps, which delivers new possibilities to detect main and epistatic effects. Furthermore, new sequencing techniques allow candidate gene based association mapping. The main aim of the project is to unravel the genetic architecture of frost tolerance and quality traits in durum. Thereby, the objectives are to (1) determine the genetic variance, heritability and correlations among frost tolerance and quality traits, (2) examine linkage disequilibrium and population structure, (3) investigate sequence polymorphism at candidate genes for frost tolerance, and (4) perform candidate gene based and genome wide association mapping.
On 18 Januar 1986 at the east-looking slope of the Kleiner Watzmann in the Berchtesgaden National Park a snow avalanche came down from an elevation of about 2.000 m to the Königssee near St. Bartholomae (610 m above see level). It destroyed 12 to 15 ha of old growth forests dominated by beech (Fagus sylvatica); about 2.000 m3 of wood were thrown down. The soil survace was not intensively effected by the snow avalange. Because the area is situated in the central protection zone of the national park no clearing procedure was done, and a free stand develeopment without any direct impact of man is allowed to take place. In 1989 permanent plots (3 transects, each starting in the surrounding forest and crossing to avalanche area) were established. Vegetation and stand structure records were carried out in 1989, 1994 and 1999. Vegetation development in the first place is characterised by (1) a re-establishment of the tree layer by the (beech) trees, which were bent to the ground but not killed by the avalanche, (2) by seedling and sapling establishment (especially Acer and Fraxinus, but not by pioneer trees) and (3) by continuing floristic composition of the ground vegetation (coverage increasing or decresing depending on the light conditions).
Perennial fodder cropping potentially increases subsoil biopore density by formation of extensive root systems and temporary soil rest. We will quantify root length density, earthworm abundance and biopore size classes after Medicago sativa, Cichorium intybus and Festuca arundinacea grown for 1, 2 and 3 years respectively in the applied research unit's Central Field Trial (CeFiT) which is established and maintained by our working group. Shoot parameters including transpiration, gas exchange and chlorophyll fluorescence will frequently be recorded. Precrop effects on oilseed rape and cereals will be quantified with regard to crop yield, nutrient transfer and H2-release. The soil associated with biopores (i.e. the driloshpere) is generally rich in nutrients as compared to the bulk soil and is therefore supposed to be a potential hot spot for nutrient acquisition. However, contact areas between roots and the pore wall have been reported to be low. It is still unclear to which extent the nutrients present in the drilosphere are used and which potential relevance subsoil biopores may have for the nutrient supply of crops. We will use a flexible videoscope to determine the root-soil contact in biopores. Nitrogen input into the drilosphere by earthworms and potential re-uptake of nitrogen from the drilosphere by subsequent crops with different rooting systems (oilseed rape vs. cereals) will be quantified using 15N as a tracer.
Comprehension of belowground competition between plant species is a central part in understanding the complex interactions in intercropped agricultural systems, between crops and weeds as well as in natural ecosystems. So far, no simple and rapid method for species discrimination of roots in the soil exists. We will be developing a method for root discrimination of various species based on Fourier Transform Infrared (FTIR)-Attenuated Total Reflexion (ATR) Spectroscopy and expanding its application to the field. The absorbance patterns of FTIR-ATR spectra represent the chemical sample composition like an individual fingerprint. By means of multivariate methods, spectra will be grouped according to spectral and chemical similarity in order to achieve species discrimination. We will investigate pea and oat roots as well as maize and barnyard grass roots using various cultivars/proveniences grown in the greenhouse. Pea and oat are recommendable species for intercropping to achieve superior grain and protein yields in an environmentally sustainable manner. To evaluate the effects of intercropping on root distribution in the field, root segments will be measured directly at the soil profile wall using a mobile FTIR spectrometer. By extracting the main root compounds (lipids, proteins, carbohydrates) and recording their FTIR-ATR spectra as references, we will elucidate the chemical basis of species-specific differences.
Changes in agroecosystem management (e.g. landscape diversity, management intensity) affect the natural control of pests. The effects of agricultural change on this ecosystem service, however, are not universal and the mechanisms affecting it remain to be understood. As biological control is effectively the product of networks of interactions between pests and their natural enemies, food web analysis provides a versatile tool to address this gap of knowledge. The proposed project will utilize a molecular food web approach and examine, for the first time, how changes in plant fertilisation and landscape complexity affect quantitative aphid-parasitoid-hyperparasitoid food webs on a species-specific level to unravel how changes in food web interactions affect parasitoid aphid control. Based on the fieldderived data, cage experiments will be conducted to assess how parasitoid diversity and identity affect parasitoid interactions and pest control, complementing the field results. The work proposed here will take research on parasitoid aphid control one step further, as it will provide a clearer understanding of how plant fertilization affects whole aphid-parasitoid food webs in both simple and complex landscapes, allowing for further improvements in natural pest control.
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