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Found 63 results.

Linking internal pattern dynamics and integral responses - Identification of dominant controls with a strategic sampling design

In hydrology, the relationship between water storage and flow is still fundamental in characterizing and modeling hydrological systems. However, this simplification neglects important aspects of the variability of the hydrological system, such as stable or instable states, tipping points, connectivity, etc. and influences the predictability of hydrological systems, both for extreme events as well as long-term changes. We still lack appropriate data to develop theory linking internal pattern dynamics and integral responses and therefore to identify functionally similar hydrological areas and link this to structural features. We plan to investigate the similarities and differences of the dynamic patterns of state variables and the integral response in replicas of distinct landscape units. A strategic and systematic monitoring network is planned in this project, which contributes the essential dynamic datasets to the research group to characterize EFUs and DFUs and thus significantly improving the usual approach of subdividing the landscape into static entities such as the traditional HRUs. The planned monitoring network is unique and highly innovative in its linkage of surface and subsurface observations and its spatial and temporal resolution and the centerpiece of CAOS.

A meta-analysis of global insecticide concentrations in agricultural surface waters

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.

The parent material as major factor for the properties of the biogeochemical interface: Integrative analysis

The formation of biogeochemical interfaces in soils is controlled, among other factors, by the type of particle surfaces present and the assemblage of organic matter and mineral particles. Therefore, the formation and maturation of interfaces is studied with artificial soils which are produced in long-term biogeochemical laboratory incubation experiments (3, 6, 12, 18 months. Clay minerals, iron oxides and charcoal are used as major model components controlling the formation of interfaces because they exhibit high surface area and microporosity. Soil interface characteristics have been analyzed by several groups involved in the priority program for formation of organo-mineral interfaces, sorptive and thermal interface properties, microbial community structure and function. Already after 6 months of incubation, the artificial soils exhibited different properties in relation to their composition. A unique dataset evolves on the development and the dynamics of interfaces in soil in the different projects contributing to this experiment. An integrated analysis based on a conceptual model and multivariate statistics will help to understand overall processes leading to the biogeochemical properties of interfaces in soil, that are the basis for their functions in ecosystems. Therefore, we propose to establish an integrative project for the evaluation of data obtained and for publication of synergistic work, which will bring the results to a higher level of understanding.

Geosuche

Die Geosuche ist ein Webservice, welcher über die EGovernment-Basiskomponente Geodaten (GeoBAK) bereitgestellt wird. Die Geosuche ermöglicht eine multikriterielle Recherche nach ausgewählten Geobasisdaten und Geofachdaten, Geoinformationen (Metadaten) sowie Portalinhalten (Webseiten, Dokumente). Sie ist zentraler Bestandteil des Geoportals Sachsenatlas und als Freie Suche bzw. Volltextsuche ausgelegt. Die Umsetzung der Suche im Geoportal als singuläres Suchfeld (Omnibox, Einfeldsuche) analog zu bekannten Internetsuchmaschinen, ermöglicht einen schnellen Einstieg der Nutzer. Die Geosuche ermöglicht im Gegensatz zu standardisierten OGC-Geodatendiensten wie z.B. OGC-WFS-Gazetteer eine performanceoptimierte Recherche, welche nicht nur auf Geodaten beschränkt ist. Die Geosuche ermöglicht aufgrund der Filter- und Sortiermöglichkeiten die Umsetzung von über die Einfeldsuche hinausgehenden Recherchemöglichkeiten. Im Geoportal ist dies über die erweiterte Suche mit z.B. räumlicher und zeitlicher Auswahlmöglichkeit umgesetzt. Weiterhin sind einzelne Objekte untereinander verknüpft. Damit ist beispielsweise die Recherche nach allen Hausnummern einer Straße möglich (Drilldown). Die Umsetzung von Formularen mit Auswahllisten für eine Recherche, die die Geosuche aufrufen, ist möglich.

Forschergruppe (FOR) 496: Poplar - a model to address tree-specific questions, Seasonal regulation of ion- and metabolite transport between poplar shoot tissues

We intend to investigate the molecular mechanisms of mineral nutrient dependent poplar physiology with special focus on potassium. This will be accomplished using two different approaches. 1. Molecular biology: We will study the regulation of ion channels and transporters by different environmental conditions, such as the effect of nutrition, salt, hormonal action, cold and drought during wood production and the dormancy-growth transitions. Phenotype analysis of transporter sense/antisense plants will be used to gain insights into the role of the transporters in tree physiology. On the basis of a laser-micro-dissection system, we will be able to prepare cDNA of distinct cell types and generate subtractive cDNAs to determine genes, specific for the differentiation of vessels and bast fibers. 2. Electrophysiological investigations: We will compare the functional properties of the transporters. Ion-fluxes and transporters, involved in cambial activation will be characterized in vivo and in vitro. The response to changes in e.g. the extracellular medium in vitro, will provide a measure for the regulation of ion transport by apoplastic factors in vivo. Based on this data sets we should be able to establish a model on the seasonal fluxes of potassium in relation to the transporter properties and dynamics in the context of tree physiology in general and xylogenesis in particular.

Novel technologies to reveal the impacts of nutrient limitation in aquatic systems: from biodiversity to biogeochemical cycles

Both lakes and oceans are important for the global carbon cycle and thus the regulation of climate processes. Due to climate change and human activities, aquatic systems are subject to increasing pressure with changes already observed at multiple levels affecting their functioning. It is therefore urgent to understand the dynamic of aquatic systems, if one wants to predict their response to changing conditions. Phytoplankton, act as engineers, initiating the incorporation of terrestrial and atmospheric compounds into the food chain and driving their biogeochemical cycling. They not only respond rapidly to their environment, they also profoundly alter aquatic chemistry, affecting the reactivity, recycling, remineralisation and therefore fate of many elements. As such, phytoplankton affect the dynamics of aquatic systems with effects at both local and global scales. Phytoplankton can thus be used as sentinel to assess the dynamics and changes in aquatic systems. One of the most prominent reported controls of phytoplankton biomass, biodiversity and productivity is nutrient limitation, reported in most of the ocean and numerous lakes. Iron (Fe), nitrogen (N) and phosphorous (P) are the main limiting nutrients in aquatic systems. Nutrient limitation affects the functioning of aquatic systems and their contribution to the global carbon cycle. Despite numerous studies, the parameters controlling nutrient limitation and their accessibility to phytoplankton (viz. bioavailability) remain largely unknown. The aim of this project is to identify nutrient (Fe, N, P) limitation in different aquatic systems, and to improve our understanding of aquatic biogeochemistry - from gene expression, chemistry and bioavailability through to the impact on biodiversity under current and future conditions. The study regions include the largest lake in Western Europe, Lake Geneva; the Southern Ocean, a pivotal region for the global carbon cycle; and the Tasman Sea, one of the most sensitive regions to predicted climate change. All these regions are associated with significant socio-economical value. Here, a rigorous multi-disciplinary laboratory and field approach will be used to provide complementary data sets to shed light on how nutrients affect the biodiversity, the biogeochemical cycles of key elements and the functioning of natural systems. The laboratory approach (1) explore the mechanisms controlling nutrient biological accessibility using relevant axenic phytoplankton cultures and (2) allows the calibration and validation of biological and chemical sensors to rapidly monitor nutrient limitation in aquatic systems. In addition, field work will (1) explore the link and the seasonality between important physical, biological and chemical parameters and (2) use perturbation experiments to investigate the complexity of the link between nutrients and natural planktonic assemblages. (...)

High-resolution climate reconstruction for phases of Holocene rapid climate change from lakes in Northern Europe: Assessing the potential of high-resolution non-destructive scanning techniques

This project had two main goals: i) to test and further develop the novel method of scanning reflectance spectroscopy in the visible spectrum (VIS-RS) and ii) to gain improved insight into Holocene climate, especially into phases with rapid climate change by applying this method to sediments from lakes in Northern Europe. In a first study, we could confirm the high potential of VIS-RS for inferring for example organic content of lake sediments. We could as well demonstrate the high potential of multivariate calibration techniques for this purpose. In a next step it should be tested to which extend more time consuming and costly sediment parameters can be inferred by means of VIS-RS. In a second study, we analysed a comprehensive data set from a pro-glacial lake in Western Norway and extracted a signal of Holocene glacier variations from this data set. Focusing on the 8.2 ka event a period characterised by rapid cooling and subsequent warming in the North Atlantic realm, we find that the decomposition of the glacier happened even faster than the glacier advance. In this study, we applied a multitude of statistical methods to i) compare sediment parameters among each other, ii) to extract signals common to all sediment parameters and iii) to transform uncertainty of age-depth models into uncertainties of glacial activity. We therefore employed methods that are widely applied in palaeoecology but that have not found their way into the field of geochemistry and sedimentology yet.

Schwerpunktprogramm (SPP) 1167: Quantitative Niederschlagsvorhersage, High-resolution Reanalyses and Impact Studies for Improving Process Understanding and Precipitation Forecast Skill based on the COPS Data Set

Quantitative Precipitation Forecast (QPF) is one of the major challenges in numerical weather prediction (NWP). This is true for QPF ranging from synoptic-scale to small-scale convection. The main goal of this proposal is to improve the short-range QPF on scales of a few hundred km and a few hours. To achieve a significant improvement of QPF on these scales the atmospheric variables, which are representing the pre-convective conditions, need to be determined. Hence an innovative combination of data assimilation techniques and observations is proposed. Within this project, 4D water vapour, as well as wind and cloud data are considered. The focus is on advanced observing systems with high future potential such as GPS, lidar, passive remote sensing from geostationary satellites as well as novel in-situ sensors. Different state-of-the-art assimilation techniques will be compared to find the optimal approach to improve QPF. After the development of suitable observation operators, the optimal use of advanced remote sensing systems will be investigated using various Observing System Experiments (OSE's) and Observing System Simulation Experiments (OSSE's). To quantify the success, model independent data sets inferred from MSG/radar, GPS, and an innovative sounding system will be used for validation.

Forschergruppe (FOR) 816: Biodiversity and Sustainable Management of a Megadiverse Mountain Ecosystem in South Ecuador, D3: Impacts of environmental change on climate and ecosystem in southern Ecuador

Subproject within the DFG research unit 816: Biodiversity and Sustainable Management Of a Megadiverse Mountain Ecosystem in South Ecuador The main aim of the project is to unveil the impacts of climate and land use change on the regional climate of the ecosystem platform, to examine effects of climate change on biodiversity for selected organismic groups by testing two different approaches, to investigate atmospheric nutrient deposition from remote sources in the framework of the NUMEX experiment as well as its future development under environmental change, and to support the research unit by providing data on vegetation activity based on remotely sensed data. Subject 1 encompasses an in-depth analysis of weather situations with an anomalous zonal overturning Walker circulation (El Niño/La Niña events) by means of a comprehensive data set gathered during previous studies. Additionally, a coupled model suite of a regional climate (WRF) and a SVAT model (CLM) will be used to conduct simulation runs for the joint scenarios of land use and global climate change. Subject 2 uses downscaled temperature data for the climate change scenarios to test effects on biodiversity with the species-area approach and the energetic-equivalence rule for moths, soil mites and trees. Subject 3 observes fog- and rain-water deposition including a back-trajectory modelling encompassing. Remotely sensed products of atmospheric chemistry and future climate/emission scenario runs are applied to disentangle present-day and future atmospheric fertilization of the mountain forest and its remote sources. Subject 4 makes vegetation products (NDVI, LAI, GPP) of different sensors available to the research unit.

Biodiversity in agroecosystems: a multi-trophic approach to metacommunities

The goal of the proposal is to explore the structure and functioning of metacommunities in ecological compensation areas at a multi-trophic level. First, we will assess the effect of plant diversity and herbivore and/or predator exclusion on metacommunity functioning in sown wildflower strips. We will document the communities inhabiting these experimental plots, paying attention at interactions between species, and with consideration of larger consumers linking these habitats with the surrounding matrix. Second, we will explore the relationship between various measures of the environment (isolation, habitat size) and descriptors of the metacommunities (diversity, composition, abundances, and productivity of various taxonomic groups, food-web structure, temporal variability, local invasions and extinctions). Third, using a high-quality dataset on quantitative food webs and the present data, we will conduct meta-analyses to test various models of community organisation (neutral models of biodiversity, species-area relationship in trophic levels, regional similarity hypothesis, food-web structure). Fourth, we will develop various models describing food-web structure and metacommunities dynamics. We will synthesize our results to develop a theory of 'meta food-webs'. Fifth, we will apply the gained knowledge to improve current agri-environment schemes. The study of species interactions in spatially structured metacommunities is comprehensive and global. As such, this project has a strong potential to provide fundamental insight into conservation biology. This project is multidisciplinary, putting together practitioners, ecologists and mathematicians, and is expected to yield important results both of fundamental and conservation relevance. We will use various methodologies to reach our goals. For the first part, we will set up an experiment with replicated sown wildflower strips where plant species richness and the abundance of major predators (foxes and birds of prey) and/or of major herbivores (voles and slugs) will be controlled (balanced incomplete block design). The other parts will rely on classical meta-analyses, multivariate statistics, and mathematical modelling. For the latter part, we will develop stochastic models to explore the dynamics of communities.

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