This project uses three different and complementary approaches to quantify local to regional evapotranspiratlon and surface energy balance partitioning. The first approach uses the seml-physlcal-, Penman-Montelth equation combined with the complementary relationshipand thermal remote sensing to derive high resolution estimates of evapotranspiratlon. The second approach uses hydna-meteorological simulations of the WRF-NOAH-MP model system down to scales of 100 m to study the effects of soll-vegetatlon-atmosphere feedbacksand mesoscale circulations on regional evapotranspiratlon with unprecedented detail. The third approach uses the thermodynamic limit on convectlve exchange to Infer the magnitude of soll-vegetation-atmosphere Interactions, atmospheric mixing processes, and local to regional evapotranspiratlon patterns. A dedicated field campaign performing micrometeorologlcal measurements of the surface energy balance and the CAOS field observations will be used to evaluate these methods. The WRF-NOAH-MP model Is also applied for quantitative precipitation forecasting by assimilating polarization radar data to Improve Initial water budget components. These approaches are evaluated In a joint synthesis activity regarding surface energy balance estimates from local to catchment scale and their closure assumptions. The synthesis of these three approaches of vastly different complexity has the potential to substantially advance our ability to understand and nDbustly predict regional evapotranspiratlon and the surface energy balance.
Im Rahmen einer Ausschreibung des Bundesministeriums für Landwirtschaft und Ernährung zur 'Nachhaltigen Waldwirtschaft in Russland' wird ein Forschungsprojekt des Instituts für Waldbau und Waldschutz der TU Dresden mit den Partnern in Tatarstan seit dem Sommer 2015 gefördert. In dem Projekt 'Optimierte Mischbestandbegründung bei Stieleichen-Winterlinden-Kulturen' (OMSK) unter Leitung von Prof. Wagner, wird einer Optimierung der Pflanzenzahlen in der künstlichen Bestandesbegründung von Stieleichen-Winterlinden-Beständen nachgegangen. Diese Waldgesellschaft stößt in Tatarstan an ihre natürliche Arealgrenze. Die Stieleiche ist als ökologisch besonders wertvoll und als ökonomisch besonders interessant anzusehen; wegen der ökologischen Grenzbedingungen ist Samenbildung allerdings ein seltenes Ereignis. So ist es absehbar, dass den tatarischen Forstkollegen das forstliche Vermehrungsgut der Stieleiche für ihre ambitionierten Erstaufforstungsvorhaben fehlen wird. Eine Möglichkeit in dieser Situation stellt die Verringerung der Eichenpflanzenzahlen pro Hektar dar. In dem Vorhaben soll deshalb der Frage nachgegangen werden, ob eine Eichen-Pflanzenzahlreduktion bei der Bestandesbegründung durch die gleichzeitige Begründung mit der Mischbaumart Winterlinde - bei bestimmten Qualitätserwartungen an die Eichenbestände - möglich ist. Winterlinden-Vermehrungsgut ist reichlich verfügbar. Zur Klärung dieser Frage und zur Ableitung optimaler Pflanzenzahlen und Pflanzschema sollen Chronosequenzuntersuchungen in Tatarstan durchgeführt werden, die einen Zusammenhang zwischen Pflanzenzahlen und Qualitätsparametern herstellen. Empfehlungen zu Pflanzenzahlen bei der Bestandesbegründung, sowie Anleitung zur Anlage von Verbandsversuchen nach Nelder sollen für die zukünftige Waldmehrung in Tatarstan günstige Voraussetzungen schaffen.
Black carbon (BC) residues from the incomplete combustion of vegetation and fossil fuels are ubiquitous in soil, sediment and water. Due to its stability, BC is an important component of the slow cycling global carbon pool. Analysis of BC in environmental matrices such as soils and sediments is complicated by its diverse nature. Sediments are the quantitatively most important sink in the global black carbon cycle and represent archives of BC deposition on local and regional scales, but the identification and apportionment of the BC sources (fossil fuel combustion versus vegetation fires) remain unclear to date. Benzene polycarboxylic acids (BPCA) are molecular markers specific for BC and are used to measure quantity and quality of BC. The method provides information about the degree of condensation and allows characterization of different forms of BC (e.g. charcoal, soot). Recent advances in BPCA analysis improved the method in terms of sample preparation and made analyses faster and more accurate. Compound specific radiocarbon (14C) dating is a powerful tool in geochemistry and archaeological sciences to trace the fate of specific molecules in soils and sediments. Up to now, 14C measurements are inaccurate for BC, as established methods measure 14C contents of oxidation resistant bulk carbon. In the proposed research project, I will follow a novel approach for BPCA separation with subsequent determination of its 14C contents. This technique will allow to precisely estimate the apportionment of sources of BC found in sediments and the age of black carbon in soils. In this project I will take advantage of an existing set of well-dated lake sediment samples. These sediment cores feature undisturbed lamination, thus providing a high-resolution record of BC depositions over more than two centuries. Analyzing this unique sample set, the qualitative and quantitative information yielded by the BPCA method and the novel approach for radiocarbon dating of BC molecular markers will be used to construct a historical record of black carbon emissions. The data will be used to apportion the measured BC concentrations to either fossil fuel or biomass burning since pre-industrial times and to identify the type of BC being preferentially preserved in aquatic sediments. The outcome of the project will help to elucidate the environmental fate of BC and will be an important contribution to the accurate calculation of a global BC budget.
CARBO-North aims at quantifying the carbon budget in Northern Russia across temporal and spatial scales. Activities address rates of ecosystem change, effects on the carbon budget (radiative forcing), and global climate and policy implications (Kyoto). Recent research on the impacts of climate change in high latitude regions has mostly assessed the equilibrium response of ecosystems, for instance what is the potential location of the arctic treeline or the southern limit of permafrost under conditions of global warming. However, transient responses are of much greater importance from a policy perspective. How quickly will the arctic treeline migrate? How quickly will permafrost thaw? How quickly will enhanced soil organic matter decay result in increased greenhouse gas emissions and leaching? Different time lags in these processes will cause significant deviations from equilibrium response. Proposed field study areas in Northeast European Russia are characterized by gradual lowland transitions in vegetation and permafrost conditions. Dedicated climate models will provide requested variables and time slices as input to ecosystem studies. Analyses will be conducted to assess the sensitivity of climate model output to a suite of land cover, ground and permafrost schemes. Proxydata will be used to evaluate rates of ecosystem change under past climatic changes. The present environment will be studied from the plot to landscape scales with a variety of approaches, including assessments of human-induced and natural disturbances. Detailed monitoring and mapping of vegetation, soil and permafrost will provide input for process-oriented studies (treeline patch dynamics; tundra/forest/river carbon fluxes; ground subsidence, etc) and GIS-based upscaling to regional levels. Results are used for integrated ecosystem modeling, calculation of net radiative effects and assessment of the sensitivity of climate model predictions to transient environmental changes. Prime Contractor: University Stockholm, Stockholm; Sweden.
Das beantragte Vorhaben soll ein verbessertes Feuerrisiko-Management unter Nutzung von Fernerkundungsdaten unterstützen. Die Methode wird in einem Untersuchungsgebiet in der Provinz Alberta, welches zusammen mit dem Nutzer gewählt wurde, angewendet und getestet. Durch die spezifischen Bedingungen in Kanada (Sonnenstand, Bewölkung) bieten SAR Daten entscheidende Vorteile. C-Band Daten und X-Band Daten werden im Zusammenhang mit Modellierungs-Lösungen für das Feuerrisiko Management in Wert gesetzt. Bei den Feuerereignissen handelt es sich meist um natürliche Vorkommnisse, die durch die lokalen Wetter, Vegetations-, Boden- und Schneebedingungen begünstigt werden. Mit dem Aufbrechen der Schneedecke im Frühjahr und den einsetzenden Austrieb der Vegetation steigt das Risiko für Feuer signifikant. Neben den Zeitpunkt des Verschwindens der Schneedecke sind insbesondere der Zustand des Boden (gefroren / aufgetaut) und der Status der Vegetation ( greening ) von Bedeutung. Dieses multifaktorielle Zusammenwirken soll mittels eines multisensoralen Ansatzes untersucht werden. Es ist beabsichtigt, Forschungs- und Entwicklungsarbeiten im Bereich SAR Methodik und Produktentwicklungen von den Partnern VISTA und Hatfield in zwei kooperierenden Projekten durchzuführen. Dieses ermöglicht, eine synergetische Nutzung der Fernerkundungsdaten anhand der jeweiligen Arbeitsschwerpunkte und Erfahrungen und eine Zusammenwirken der spezifischen Aufgabenbereiche und Kompetenzen der beiden Partner. Neben der Fernerkundung werden auch flächenhafte Modellierungsansätze mit dem Prozessmodell PROMET, verwendet. Hierdurch können Informationen bereitgestellt werden, die aus der Fernerkundung allein nicht zu jedem Zeitpunkt und für jeden Ort zur Verfügung stehen. Durch die Zusammenarbeit werden die Dienste der Partner verbessert, als auch die bestehenden Entwicklungen an neue Fragestellungen angepasst und die Anwendungsbereiche erweitert um zukünftig weitere Dienste zu etablieren.
A very high percentage of the agronomically used area in Switzerland is covered by grasslands. This land use type is present at various altitudes (up to alpine regions), where environmental conditions, community structure, nutrient dynamics and productivity vary in a wide range. Results obtained during phase 1 of the NCCR Climate, but also by other research groups globally, lead to the conclusion that - besides an increase in mean temperature - temperature variability will increase considerably in Central Europe (Schär et al. 2004). However, the response of entire grassland systems to drought and heat remains unclear. Many earlier studies focused only on soil or vegetation (often only above-ground; e.g. Pfisterer and Schmid 2002), but did not consider the entire ecosystem with its interactions between different ecosystem components (e.g., Kahmen et al. 2004). We know that heat affects photosynthesis and - as a consequence - net carbon fluxes and plant productivity, as reported for example for oak (NCCR Phase 1; Haldimann and Feller 2004). How climatic factors affect above- and below-ground processes in temperate grasslands and how to implement safe management strategies to mitigate changes is less known. We will focus on drought and heat effects on managed grasslands. In grasslands, much of the biological activity and resource turnover happens below-ground; here carbon stocks can be as large as the annual above-ground harvested biomass. However, harvest and grazing typically take place above a certain height (typically 3 - 7 cm above ground), leaving behind large quantities of organic carbon as stubble (standing living and dead biomass) and litter. While the plant biomass above the cutting/grazing height is important for agricultural purposes (yield), biomass below this height is relevant for regrowth after cutting/grazing, for the development and maintenance of the root system and therefore resource use, for the transfer but also loss of carbon, nitrogen and other nutrients to the soil, and for soil carbon sequestration (Avice et al. 1996). The quantities and contributions of these various components to the total ecosystem depend on the allocation of assimilates and nutrients in the plants, on the metabolic activities and on the redistribution during senescence (Avice et al. 1996, Jeuffroy et al. 2002) as well as on microbial activities in the soil. The so far poorly quantified transfer rate for carbon from above-ground litter to below-ground organic matter is a key issue in this context (Lal 2004). In addition, all these processes are influenced by climatic and environmental conditions. For example, Palta and Gregory (1997) reported that wheat allocated relatively more assimilates to the roots under limited water conditions compared to adequate soil water. Kahmen et al. (2004) found stable above-ground productivity but increased below-ground productivity under drought conditions in grasslands of varying species richness. (abbrevia
Research aims - The aim of this project is to demonstrate whether increased biodiversity and net primary production lead to increased carbon storage in the ecosystem, especially in the largest carbon pool, the mineral soil, and thus reduces the release of greenhouse gases. Climate change (nitrogen deposition, summer droughts, vegetation fire) - We will analyse plant-soil feedbacks in laboratory experiments, using our newly build Multi Isotope labelling in Controlled Environment (MICE) facility, and in three of the field sites (tropical, temperate, boreal) using transplanted model mini-ecosystems. Global change includes many processes, and we focus on three processes, key to the terrestrial carbon cycle, i.e. increasing chronic atmospheric nitrogen deposition, widespread summer droughts, and more frequent wildfires, with yet unknown consequences for the carbon cycle. We will use the MICE facility to manipulate mini-ecosystems (plants and soil from the three field sites) and expose them to four climatic scenarios: todays equivalent climate (corresponding to the site), increased nitrogen deposition, drought and post-fire conditions (by pyrolising the plant biomass). The plant-soil system will be labelled with stable isotopes (13C, 15N) in order i) to investigate the changes in organic matter dynamics when climate changes are applied and ii) to produce highly labelled experimental material that could be traced in the field. We will transplant the manipulated mini-ecosystem, from the MICE facility to the three URPP GCB sites Siberia, Laegeren and Borneo (tropical, temperate, boreal). The mini-ecosystems will contain highly labelled material (13C and 15N in fresh biomass and charred biomass) in order to follow fluxes related to C losses from the soil (CO2 and organic matter dissolved in water), as well as processes involved in the stabilisation of soil C (microbial, physical and chemical mechanisms). Using a large number of replicates will allow us to follow the underlying processes of C stabilisation in soil and vegetation at a high spatial and temporal precision. Biodiversity experiment - We will use the MICE chambers to grow different species of trees and grasses labelled with 13C (and potentially 15N, 18O and 2H) under todays climatic conditions. Then we recombine the different species (1, 2, 4, 8 species) and transplant them to the temperate site at Laegeren. In the field we can follow the total carbon fluxes and the contributions from the isotopically labelled decomposing biomass, and the living biomass.
Remotely sensed vegetation indices are widely used to detect greening and browning trends; especially the global coverage of time-series normalized difference vegetation index (NDVI) data which are available from 1981. Seasonality and serial auto-correlation in the data have previously been dealt with by integrating the data to annual values; as an alternative to reducing the temporal resolution, we apply harmonic analyses and non-parametric trend tests to the GIMMS NDVI dataset (1981-2006). Using the complete dataset, greening and browning trends were analyzed using a linear model corrected for seasonality by subtracting the seasonal component, and a seasonal non-parametric model. In a third approach, phenological shift and variation in length of growing season were accounted for by analyzing the time-series using vegetation development stages rather than calendar days. Results differed substantially between the models, even though the input data were the same. Prominent regional greening trends identified by several other studies were confirmed but the models were inconsistent in areas with weak trends. The linear model using data corrected for seasonality showed similar trend slopes to those described in previous work using linear models on yearly mean values. The non-parametric models demonstrated the significant influence of variations in phenology; accounting for these variations should yield more robust trend analyses and better understanding of vegetation trends.
Vegetation & Ecosystems: Within the vegetation research statistical and special hyperspectral analysis procedures are used to develop new methods to predict canopy biochemistry, such as nitrogen and carbon concentration or water content. Biochemical processes are all related to the foliar chemistry of vegetation and thus to the carbon and nitrogen cycles. Hence, biochemical information products contribute to many environmental applications. For instance ecosystem models can be parameterized with the generated products that can help to better understand CO2 fluxes and net primary production (NPP) in the framework of the Kyoto Protocol. Traditional measurement of forest canopy level biochemistry is time-consuming, expensive and spatially constrained. Remote sensing allows for repeatable and continuous prediction of biochemical information over a wide spatial scale and thus facilitates the understanding of ecosystem functions. For the retrieval of biochemistry products to be used for environmental applications, the transfer of the developed methods from airborne hyperspectral to spaceborne data is fundamental. This transfer involves spectral and spatial up-scaling. Additionally, spaceborne reflectance data contain angular effects due to the sensor field of view and observation geometry, which can finally influence biochemistry estimates. However, multi-angular reflectance data contain added information about vegetation structure. Since correct biochemistry mapping is linked to accurate vegetation structure, forest biochemistry products may be improved with multi-angular data. Our goals in the field of biochemistry prediction are to transfer the developed airborne-based methods to spaceborne data and to evaluate different methods for up-scaling. Water resources: The SNF project targets at the key aim of the joint EU, ESA GMES initiative to establish operational services for the assessment of water resources in terms of quality, quantity and usage. It has been defined as a major challenge in the scope of GMES activities and it is of crucial importance in most developing countries and at a global level (EC, 2005). RSL is developing new methodology (semi-empirical and analytical methods) for the retrieval of water constituents in order to establish scientific algorithm development activities with special emphasis on APEX retrieval algorithms for water constituent s retrieval and the discrimination of macro phytes and algae types. Thanks to the unique performance, the APEX instrument will facilitate the observation of regional scale features (e.g., Harmful Algae Blooms) and enable the study of complex waters with unprecedented accuracy. The development of remote sensing algorithms to retrieve phytoplankton species and physiology is a challenging endeavor of high importance to assess biological activities in the water and therefore water quality by better means. (abridged text)
Roots are currently discussed to store considerable amounts of carbon in the subsoil. Although it is well known that roots can penetrate the subsoil and deep subsoil (greater than 2 m) several meters deep, it remains unclear, how much carbon they contribute, if they lead to net carbon sequestration in the long-term and under which conditions they lead to carbon accumulation. Rhizoliths and biopores are root-related features that frequently occur in soil and underlying soil parent material. Recent studies in unconsolidated sediments show that they enable investigating the long-term effects of root penetration even after the lifetime of the source plant and thus the assessment of sustainable impacts of roots on subsoil organic matter (OM). While other research groups deal with the subsoil less than 2 m, (eg German Research Foundation (DFG) Research Group SUBSOM the current project focuses on the deep subsoil (greater than 2 m), where a significant overprint of OM is expected. In fact, this part of the subsurface is usually not regarded by soil scientists, but of large interest for paleoenvironmental researchers as valid e.g. for loess-paleosol sequences. So far, the effect of roots on subsoil OM was only studied on a single site in SW Germany during a precursor project, DFG (WI2810/10). Based on that project, the current proposal aims at the investigation of the transferability of the results to other sedimentary settings and ecological contexts. At several sites along a NE-SW transect across Europe (from The Netherlands across Germany, Switzerland, Austria, Hungary towards Serbia), unconsolidated material like dune and fluvial sands, as well as loess-paleosol sequences will be investigated with respect to OM quantity and quality as influenced by root penetration. Preliminary investigations of six potential sites in Germany, Hungary and Serbia showed that biopores and other root-related features can reach similar abundances in different settings. Nevertheless, consequences for OM sequestration and turnover may be different, depending not only on the respective source vegetation but also sedimentary properties. The target of the current project is to identify carbon losses or sequestration related to root penetration, which will be assessed by bulk organic and inorganic carbon contents as well as a variety of lipid biomarkers including alkanes, fatty acids, alcohols, glycerol dialkyl glycerol tetraethers and suberin markers. The combination of these biomarkers enables the assessment of root-related overprint, if transects from root features to surrounding material free of them are investigated. The data will be fed into the VERHIB model for source apportionment of sedimentary and root-related OM. (abridged text)
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