Das Projekt "DFG Extinction debt - Interaktive Effekte von historischen Landnutzungsveränderungen und aktuellen Umweltveränderungen auf die Pflanzenartenvielfalt der Krautschicht in Laubwäldern gemäßigter Breiten" wird/wurde gefördert durch: Deutsche Forschungsgemeinschaft. Es wird/wurde ausgeführt durch: Leibniz-Zentrum für Agrarlandschaftsforschung (ZALF) e.V., Institut für Landnutzungssysteme und Landschaftsökologie.Landnutzungsveränderungen stellen eine erhebliche Bedrohung für die Artenvielfalt dar. In weiten Teilen Europas haben umfangreiche Landnutzungsveränderungen bereits vor einigen Jahrhunderten stattgefunden, als ausgedehnte Wälder gerodet wurden, um Acker- und Weideland zu gewinnen. Später fielen die landwirtschaftlichen Flächen vielerorts brach und wurden wieder aufgeforstet. Inzwischen mehren sich die Hinweise, dass diese historischen Landnutzungsveränderungen noch heute verspätete Reaktionen in der Bodenvegetation von Wäldern hervorrufen. In historisch alten Waldfragmenten ist eine 'Aussterbeschuld' zu bezahlen, während in neuzeitlichen Waldfragmenten ein 'Besiedlungskredit' zu zahlen ist. Unser Wissen über das Ausmaß von Aussterbeschuld und Besiedlungskredit in mitteleuropäischen Laubwäldern ist jedoch sehr begrenzt. Auch ist unklar, in welchem Umfang diese tatsächlich durch die Pflanzenarten bezahlt werden. Waldpflanzen werden nicht nur durch historische Landnutzungsveränderungen beeinflusst, sondern auch durch verschiedene jüngere Umweltveränderungen, z.B. atmosphärische Deposition, erhöhten Äsungsdruck und Klimawandel. Die meisten Langzeitstudien betrachten diese Faktoren einzeln, vernachlässigen dabei aber, dass diese sowohl untereinander als auch mit den Nachwirkungen historischer Landnutzungsveränderungen interagieren. Mit diesem Forschungsprojekt möchten wir uns diesen Wissenslücken widmen. Unsere wesentlichen Ziele sind a) Aussterbeschuld und Besiedlungskredit in historisch alten bzw. neuzeitlichen Laubwäldern zu quantifizieren, b) festzustellen, in welchem Umfang Aussterbeschuld und Besiedlungskredit über die letzten fünf Jahrzehnte bezahlt wurden, und c) wesentliche Interaktionen zwischen den Nachwirkungen historischer Landnutzungsveränderungen und den Auswirkungen aktueller Umweltveränderungen auf die Artenvielfalt nachzuweisen. Die Untersuchungen sollen in der Prignitz (Nordostdeutschland) durchgeführt werden. Für diese Region stehen uns außergewöhnlich gute historische Daten zur Verfügung. Mit Hilfe von topographischen Karten aus dem späten 18. und 19. Jahrhundert kann die Landnutzungsgeschichte rekonstruiert werden. Die historische und aktuelle Landschaftskonfiguration sollen in Beziehung gesetzt werden zur aktuellen Artenvielfalt in den Laubwaldfragmenten, um so Aussterbeschuld und Besiedlungskredit zu quantifizieren. Außerdem werden wir die Artenzusammensetzung in mindestens 200 semipermanenten Aufnahmeflächen von 1960 erneut untersuchen, um Veränderungen in Artenvielfalt, floristischer Differenzierung zwischen den Wäldern (Betadiversität) und funktionaler Zusammensetzung festzustellen. Sowohl gemessene Standortbedingungen als auch das arteigene Verhalten der Pflanzenarten gegenüber verschiedenen Umweltfaktoren werden dazu dienen, die beobachteten Veränderungen in Artenvielfalt und Zusammensetzung auf die interaktiven Effekte von historischen Landnutzungsveränderungen und aktuellen Umweltveränderungen zurückzuführen.
Das Projekt "Biodiversität und Ökosystemleistungen kleiner Waldfragmente Europäischer Landschaften (smallFOREST)" wird/wurde ausgeführt durch: Leibniz-Zentrum für Agrarlandschaftsforschung (ZALF) e.V., Institut für Landnutzungssysteme und Landschaftsökologie.Generelles Ziel von smallFOREST ist die Charakterisierung und Quantifizierung von Biodiversität und dazu in Beziehung stehenden Ökosystemleistungen auf verschiedenen Skalen, und diese wiederum miteinander in Beziehung zu setzen, in kleinen Waldflächen, die in unterschiedlichen Agrarlandschaften entlang eines Südwest-Nordost-Transktes des temperaten Europas eingebettet sind.
Das Projekt "Nitrogen effect on molecular dynamics in forest soils (end of thesis)" wird/wurde gefördert durch: Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung. Es wird/wurde ausgeführt durch: Universität Zürich, Geographisches Institut.Atmospheric nitrogen deposition affects many forests and their ecosystem functions, including organic matter cycling in soils of temperate forests. But it is not clear how, and what the underlying mechanisms are. Here we asked the question: Do compounds with high intrinsic nitrogen content (typical for microbially-derived biomass) respond differently to atmospheric nitrogen deposition than compounds with low nitrogen content (such as plant-derived biomass)? Two facts delayed the progress of the project in the first year. From May 2010 to June 2011 the PhD student Marco Griepentrog successfully completed make-up classes for the recognition of his Fachhochschule degree by the University of Zurich. His workload (30 credit points or 900 working hours) was 50Prozent of the annual workload of a full time student, and delayed the progress of the project. Furthermore the PI Dr. Alexander Heim has left research in November 2010 and started a new position in industry and the co-PI Prof. Michael Schmidt stepped in as PI. Despite the delay the project eventually progressed well thanks to the hard-working PhD student Marco Griepentrog, who worked in the lab and simultaneously compiled a detailed methodological literature review on preparative soil fractionation procedures. His review revealed striking discrepancies in the application of this frequently used method, and was submitted to a peer-reviewed journal and is still under revision. With a competitive travel grant from the European Science Foundation, Marco Griepentrog worked at the University of Ghent (Belgium) and could measure compound-specific isotope ratios of amino sugars reliable in soil density fractions for the first time, using a novel analytical technique. This was the first time that amino sugars were measured in density fractions, and we could show that especially bacterial amino sugars were associated with soil minerals. Furthermore, when combined with stable isotope labeling, it became evident that amino sugar turn over much slower when associated with soil minerals. Another unexpected result was that fungal residues turn over at the same rate as total organic carbon, while bacterial amino sugars turn over slower. The fact that fungal amino sugars turn over faster than bacterial amino sugars contradicts with previous assumptions, and our measurements are the first to show that. Results have been presented at several international conferences, and now a manuscript circulates between co-authors to be submitted to a high impact scientific journal later this year. For the final year, we plan to focus on another compound class and propose a change of the initially planned target compound lignin. Own results showed that the isotopic label might not be detectable in lignin but in fatty acids, since they have been shown to turnover faster. usw.
Das Projekt "Climate change and tree physiological response in Siberia and in the Alps during warm and cold periods of the last 1500 years" wird/wurde gefördert durch: Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung. Es wird/wurde ausgeführt durch: Paul Scherrer Institut, Labor für Atmosphärenchemie.High-latitude and high-altitude forests are sensitive ecosystems that are more exposed to global warming in recent decades than forests of the temperate zones. As a result of the accelerating climate change, these forests may undergo severe changes regarding spatial distribution and species composition, the carbon, water and nitrogen cycles. This will have tremendous consequences for the sustainable functioning of the ecosystems and potential feedbacks to the atmosphere, such as increased release of greenhouse gases from soils. Insight into extreme past climate conditions and the response of Boreal and Alpine forests to these conditions provides an invaluable analogy for the potential future response. Trees from temperature-limited sites are known as sensitive proxies for climate reconstruction, while the availability of well-preserved wood in these regions enable the deciphering of past environmental conditions for centuries up to millennia. In this project, our main goal is to obtain a comprehensive description of the climatic and environmental changes during pronounced warm and cool periods of the past 1500 years. We want to achieve this goal by addressing the following three objectives: 1) we aim to better quantify the magnitude of temperature and precipitation variability for known periods of extreme climate conditions, focusing on the cold anomaly around 536AD, the Medieval optimum period, the 'little ice age' period and the last century, 2) we will use the combined analysis of tree-ring width, carbon and oxygen isotopes and physiological models to decipher the response of the trees in terms of photosynthesis and water-use during these periods, 3) and we want to determine the spatial and temporal coherence of large-scale climate events for Europe and northern Eurasia. We have access to unique dated tree-ring material from three sites in Northern Siberia and one site from the Alps that cover the investigation periods. We will use ring-width as a measure of growth and stable isotope ratios of carbon and oxygen of tree-ring cellulose as a measure of photosynthesis and water-use, while both isotopes are also related to temperature and precipitation. By applying a coupled photosynthesis-isotope fractionation model, which is driven by microclimate, photosynthesis, and soil water balance, we will be able to relate climatic to physiological changes. The results of the project will enable us to better understand the response of trees in temperature-limited environment to a changing climate.
Das Projekt "Belowground niche separation and competition in tree species mixtures" wird/wurde gefördert durch: Deutscher Akademischer Austausch Dienst. Es wird/wurde ausgeführt durch: Universität Freiburg, Waldbau-Institut.Root competition for water and nutrient among species is an ubiquitous feature of terrestrial plant communities influencing abundance and distribution of plants and the dynamics of their communities. The relationship between biodiversity and ecosystem functioning has emerged as a central issue in ecological and environmental sciences. It is commonly believed that increasing species richness increases the stability of communities. Higher plant species diversity might lead to increased exploitation of spatially heterogeneous resources by spatial niche complementarity. Tree species mixtures are generally believed to enhance ecosystem functioning in forests by niche partitioning and complementary resource exploitation due to differences in tree height, crown form, root depth and/ or phenology. In the past, however, most studies focused on the aboveground interaction and coexistence of the tree species, while factors controlling belowground species interactions remain less clear. There is experimental evidence to suggest that below-ground competition in herbaceous communities is size-symmetric in homogeneous soil. However, recent studies in tree communities indicate that fine-root competition may be asymmetric. The main purpose of this project is to characterize the underground niche separation and competition in relation to tree species diversity in mixtures comprising spruce, beech, oak and Douglas fir. Structural traits and spatial distribution of fine roots were investigated using a soil core method and fine-root growth is being assessed using the ingrowth core technique at a site in Kaltenborn, which is part of the long-term biodiversity-ecosystem functioning experiment with tree species of temperate forests (BIOTREE). The objectives of this study were to test the following hypotheses: (1) overall level of soil exploitation increases with the tree species diversity; (2) competitive ability belowground is size-symmetric, and (3) the below-ground competitive ability is species specific. As part of this investigation, we will explore the potential of using Near-infrared reflectance spectroscopy to identify the species identity of fine roots of the different tree species and to quantify the contribution of different fine roots in mixed root samples.
Das Projekt "Effects of contemporary and historical gene flow in maintaining the genetic diversity of fragmented Araucaria araucana populations" wird/wurde gefördert durch: Deutscher Akademischer Austausch Dienst. Es wird/wurde ausgeführt durch: Universität Marburg, Fachbereich Biologie, Professur Naturschutzbiologie.Araucaria araucana ( Molina) K. Koch. is a species endemic to the southern South American temperate forest that grows in a reduced area between 37º 20' and 40º 20' S (Veblen et al., 1995). It represents the main food and economical resource of the aborigine communities (Mapuches) which lives in and from these forests. The great exploitation suffered by this species in the past, the long periods of fires and the intense human activities had led to a high level of erosion of its genetic resources, mainly in the eastern edge of its distribution range in Argentina where highly fragmented populations occur. Moreover, the complete absence of natural regeneration is driving these eastern populations to its extinction. For this reason, the species is currently protected in Argentina by regulations of Lanin National Park and Neuquen Province Government. Besides, it was recently included in CITES, Convention on International Trade in Endangered Species of Wild Fauna and Flora. However, little is known about its genetic variation and the recently began studies (Bekessy et al., 2002; Izquierdo et al., 2002; Gallo et al., 2003; Marchelli, Ziegenhagen & Gallo, 2003) should be complemented. The objective of this proposal is to study gene flow among fragmented populations in the Patagonian steppe in order to provide information for conservation strategies. Furthermore, the present project will allow the continuity and reinforcement of a long-lasting cooperation between the two groups that began in 1996.
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