Das Projekt "Subproject 6: Soil Properties and Soil Erosion" wird vom Umweltbundesamt gefördert und von Eberhard Karls Universität Tübingen, Fachbereich Geowissenschaften, Abteilung Bodenkunde und Geomorphologie durchgeführt. The objective of the recently established Chinese-European joint research project 'BEF China' (DFG Research Unit 891) is to analyze the influence of tree and shrub species diversity on ecosystem functioning and services in one of the most prominent diversity hotspots in the northern hemisphere. Using a pool of 96 native tree and shrub species the project will plant a total of 345.600 trees and 277.824 shrubs to establish experimental forest stands, varying in both tree and shrub species richness, on a total area of about 100 ha. A range of biodiversity and ecosystem variables will be measured to assess community dynamics and its relation to primary productivity, carbon and nitrogen storage, nutrient cycling, and prevention of soil erosion, a so-far disregarded ecosystem service in other projects but with prominent importance for this region. Cooperation partners in Europe are the University of Halle, the University of Lüneburg, the University of Tübingen and the ETH Zürich. In China, the Chinese Academy of Sciences (CAS) in Beijing (Botany, Ecology) and Nanjing (Soil Science) contribute to the project. Subproject 6: Soil Properties and Soil Erosion: At the Geographical Institute in Tübingen, Subproject 6 (Soil properties and soil erosion) is situated. Two process systems will be analyzed in this subproject: (a) modification of kinetic energy of precipitation by its pass through the tree canopy and the shrub layer, and (b) connection between surface runoff, sediment transport and changing intrinsic soil properties as a function of biodiversity gradients. In the framework of the Research Unit, Subproject 6 also covers spatial and pedological aspects of soil genesis, substrate characteristics, landscape development, and land use history.
Das Projekt "Preparatory Meeting of a joint NSFC-DFG Research Proposal on a new Forest Biodiversity and Ecosystem Functioning Experiment in Subtropical China" wird vom Umweltbundesamt gefördert und von Universität Halle-Wittenberg, Institut für Biologie , Mikrobiologie durchgeführt. This project prepares a workshop of each seven to eight scientists from Europe and China for the preparation of a joint NSFC (National Science Foundation of China) and DFG research proposal. The workshop will last for three days and includes a meeting at the Martin Luther University in Halle and at the Max-Planck Institute of Biogeochemistry in Jena as well as visits to field sites of the BIOTREE and the Jena grassland experiments.The proposal to be prepared will focus on novel and so-far disregarded aspects of forest Biodiversity and Ecosystem Functioning (BEF) experiments: the experiment will be the first BEF project in the subtropics, it will focus both on tree species (as main plot treatments) and shrub species (as subplot treatments) for establishing biodiversity levels, it will include sub-subplot manipulations as well as soil erosion and invasability as relevant ecosystem services. In addition, the experimental approach will be combined with observational studies. The consortium will include forest scientists, plant ecologists, soil scientists, zoologists, and hydrologists, teaming up Chinese and European researchers in the same methodological fields.
Das Projekt "Quantification of ecosystem properties and functions: greenhouse gas emissions from permafrost-affected soils on the Tibetan Plateau as example" wird vom Umweltbundesamt gefördert und von Eberhard Karls Universität Tübingen, Fachbereich Geowissenschaften, Abteilung Bodenkunde und Geomorphologie durchgeführt.
Das Projekt "Controls of plant biodiversity on water flux partitioning in grassland ecosystems" wird vom Umweltbundesamt gefördert und von Eidgenössische Technische Hochschule Zürich, Institut für Agrarwissenschaften, Departement Biologie durchgeführt. Global environmental change is predicted to result in increased frequency and intensity of extreme climatic events, including severe droughts and intense precipitation events (IPCC, 2001; IPCC, 2007). The determination and partitioning of water use of entire ecosystems will thus gain increasing importance under future climatic conditions (IPCC 2007). Studying the effects of plant diversity on ecosystem water fluxes is also a crucial aspect of our understanding of the mechanisms underlying the response of ecosystems to global change as well as the direction and magnitude of potential feedback effects of ecosystems on the hydrological cycle and the atmosphere. However, up to now, biodiversity-ecosystem functioning studies have neglected the water cycle almost completely. In the proposed project, the controls of plant diversity (i.e., species richness and functional group richness) on ecosystem water fluxes, their partitioning into soil evaporation and transpiration as well as plant water uptake patterns will be assessed in grassland ecosystems with the following objectives: - To quantify water losses from grassland ecosystems of varying plant diversity to the atmosphere (evapotranspiration fluxes); - To partition the evapotranspiration flux into its soil evaporative and vegetation transpiration components; - to identify the environmental constraints of plant water sources as a function of plant diversity. The study will be carried out at The Jena Experiment, a large biodiversity experiment in which experimental plant community plots of varying species composition, but also species and functional group richness are studied since 2002. We propose to use micrometeorological techniques to measure the ecosystem evapotranspiration flux (ET) and partition it into vegetation transpiration (T) and soil evaporation (E) at the ecosystem level, as well as to use stable isotope analyses to identify the source water of transpiration during intensive field campaigns at times of different water availability. The expected outcomes of the project proposed are manyfold. Using an innovative combination of techniques, we can provide a proof-of-concept to a scientific community (e.g. biodiversity, population biology, plant ecology communities) that typically has little to no knowledge about the great potential of such methodology. We will obtain highly relevant data on the relationships between plant diversity and water fluxes, their component fluxes and environmental drivers, information that does not exist at the moment. Moreover, we then can assess land surface-atmosphere coupling and the impact of climate change on grassland ecosystems, one of the major land use types in Europe and globally.
Das Projekt "Alpine ecosystems in a changing climate: experimental CO2 enrichment and warming" wird vom Umweltbundesamt gefördert und von Eidgenössische Forschungsanstalt für Wald, Schnee und Landschaft, Eidgenössisches Institut für Schnee- und Lawinenforschung durchgeführt. Within the next decades, a two-fold increase in CO2 concentrations and a rise in temperatures by 1.4 to 5.8 C can be expected (IPCC 2001). Temperature changes in the past decades have been more pronounced in alpine and high-latitude ecosystems than in most other regions of the world (IPCC 2001). Alpine ecosystems are particularly sensitive to environmental changes because they represent a boundary ecosystem that is subjected to extreme climatic conditions. Since temperature and CO2 are key factors that regulate many ecosystem processes, the changing climate will have large effects on vegetation and soils. In this proposal, we intend to analyze effects of manipulated temperature and CO2 in alpine ecosystems at treeline. Our major aim is to study potential feedbacks between climate change, plant growth and ecosystem processes. Although the European Alps are certainly the most studied of all high mountain ranges in the world, predictions of potential impacts of climate change on ecosystems are mainly based on modeling studies or on observations of inter-annual and spatial variability. There are only a few attempts to manipulate climatic conditions in situ. A combination of an experimental increase in CO2 and temperatures in the Alps has not been carried out before. In the proposed project, we enrich experimental plots with CO2 using a FACE approach and increase temperatures with heating cables at the soil surface. The experiment has already been set up at a treeline site near Davos. The CO2 enrichment was started in 2001 and increased CO2 concentration to 550 ppm. During the 6th year of operation, as part of a co-operation with a French team, a parallel soil warming treatment was installed on half of the test plots in a crossed design with the CO2 treatment, which successfully increases soil and air temperatures by 3K. We aim at investigating the interactive effects of elevated CO2 and warming on plant growth, biodiversity and ecosystem responses. Our proposed study addresses the following key questions: Will effects of elevated CO2 persist in the longer term and will these effects change under increased temperatures? How does biodiversity and the dominant vegetation, i.e. dwarf shrubs vs. trees, react to elevated CO2 and warming? How does elevated CO2 and warming affect key ecosystem functions such as nutrient uptake and decomposition? The focus will be on the two major tree species European larch and Mountain pine and on the dominant dwarf shrub species, especially Vaccinium myrtillus and V. uliginosum. Measurements of plant growth will include length increment, productivity, phenology and reproduction. Changes in biodiversity will be monitored
Das Projekt "Microbial control of ecosystem functioning" wird vom Umweltbundesamt gefördert und von Forschungsanstalt Agroscope Reckenholz-Tänikon ART durchgeführt. Nutrient loss from ecosystems has become of global major global concern as it reduces the sustainability of ecosystems and because it causes eutrophication of surface water. In this project we investigate whether soil fungi enhance ecosystem sustainability by preventing nutrient leaching loss after rainfall. Background: Leaching of nutrients (nitrogen and phosphorus) from fertile agricultural ecosystems has become of major global concern because it causes eutrophication of surface water with adverse consequences for human health and water quality. Moreover, losses from infertile ecosystems can reduce plant productivity and ecosystem sustainability if there is no additional nutrient input. Hence, it is of critical importance to understand which mechanisms prevent nutrient loss and retain nutrients inside ecosystems. Besides lateral transport of nutrients via soil erosion and surface runoff, vertical movement through the soil profile (e.g. leaching) has been recognized as an important process contributing to nutrient loss. Until now there are no studies that tested whether mycorrhizal fungi can reduce nutrient losses. This is surprising because mycorrhizal fungi are often very abundant in the soil and play a key role in the nutrient cycle of plant communities. Mycorrhizal fungi can forage highly effectively for nutrients in the soil and, by doing so they could prevent leaching of nutrients (e.g. in winter or during periods with heavy rainfall). Aims: The following key questions are investigated in this project: 1. Can mycorrhizal fungi reduce nutrient loss from experimental grassland? 2. Can arbuscular mycorrhizal fungi reduce nutrient leaching losses at high soil fertility, low temperatures and when rainfall intensity increases? 3. Is ecosystem sustainability (measured as nutrient retention and reduced nutrient loss after rainfall) enhanced by the presence of diverse communities of arbuscular mycorrhizal fungi? Relevance: It has been reported that the available phosphate sources will be depleted in about 50 years and some authors suggest that we will face a phosphate crisis endangering agricultural production. Thus, it is of critical importance to understand whether mycorrhizal fungi can reduce phosphorus loss from soils. Moreover, the production of nitrogen fertiliser is energetically expensive and high levels of nitrate in groundwater are of concern because they can pose a significant health risk and have a negative impact on downstream ecosystems. Hence, this shows that there is a need to better understand which factors influence the N-cycle and reduce N-losses.
Das Projekt "Mechanisms underlying plant community productivity, stability and assembly (D-A-CH/LAE)" wird vom Umweltbundesamt gefördert und von Universität Zürich, Institut für Evolutionsbiologie und Umweltwissenschaften durchgeführt. Previous work demonstrated diversity effects on plant community productivity, stability and assembly. However, underlying mechanisms are still largely unknown. Therefore, we address such mechanisms based on the long time series of plant performance data provided by the Jena Experiment, on new experimental manipulations and on complementary data about aboveground plant-plant and plant-pathogen interactions. In work package 1, we test whether complementarity increases over time in the main and dominance experiments of the Jena Experiment. Furthermore, we compare community dynamics without and with invasion to test how community stability is related to fluctuations in plant species abundances. In a new trait-based experiment we test whether deliberately large trait differences maximize complementarity. In work package 2, we derive and compare matrices of pair-wise plant interaction coefficients from glasshouse experiments and the main and dominance experiments. We use these interaction matrices to predict diversity effects in mixtures. In work package 3, we use the invasion treatment to test whether community assembly under invasion leads to convergence of diversity and productivity of all communities, but different species composition of initially different communities.
Das Projekt "Functional significance of tree diversity for nutrient dynamics in a tropical plantation" wird vom Umweltbundesamt gefördert und von Eidgenössische Technische Hochschule Zürich, Institut für Agrarwissenschaften, Departement Biologie durchgeführt. The main objective of this project is to study effects of altered tree species richness on the functioning of ecosystems. As a model system, we use an experimental plantation in Panama, Central America, which has been established in 2001. A total number of 24 experimental tree stands ('plots') were planted with one, three or six native tree species. By comparing the performance of these different plots, we are aiming to quantify the consequences of varying species diversity. For further information, see also: http://biology.mcgill.ca/faculty/potvin/sardinilla.htm http://www.biotree.bgc-jena.mpg.de/ We concentrate on diversity effects on nutrient cycling with special emphasis on nitrogen (N) and phosphorus (P). We aim at quantification of the uptake of both N and P to plants, organic N mineralization in soil, and losses through leaching down the soil profile. More specifically, we want to understand the mechanisms underlying any diversity effects, such as complementarity in resource uptake, adopting isotope tracer studies. Because even basic information is lacking about occurrence of mycorrhizal associations in most tropical tree species, we are currently examining to what extent the trees establish mycorrhizal associations and of which types. We shall gather information on possible effects of tree species richness on both the diversity and community structure of mycorrhizal communities. Additionally, we will also address to what extent different tree species benefit from mycorrhizal associations. Our main hypothesis is that, in contrast to monocultures, plots with higher tree species richness show complementary uptake of soil nutrients, either because of different spatial or temporal pattern of nutrient acquisition, or association with specific mycorrhizal fungi of the different trees. The nutrient portioning that we expect in the mixed, more diverse stands will result in enhanced net flow of nutrients from soil to plants, as well as to lower N losses from the system. Since afforestations with fast-growing, often exotic tree species planted in monocultures are strongly increasing in the tropics, but may cause environmental problems, this project may help to design ecologically sustainable ways to establish new plantation forest.
Das Projekt "Determinants of microfauna community structure and multi-trophic diversity effects on ecosystem functioning in natural bromeliad mesocosms" wird vom Umweltbundesamt gefördert und von University Vancouver, Department of Zoology durchgeführt. This study examined food webs within bromeliad plants in Costa Rica to reveal general mechanisms maintaining species diversity and to predict consequences of species extinctions for the functioning of ecosystems. Humans are responsible for the destruction of pristine ecosystems around the world, causing large-scale extinctions of animal and plant species. However, we still lack the basic knowledge of the mechanisms that allow species to coexist in the first place. Furthermore, with each species that goes extinct, the interactions and functions of this species in the ecosystem are lost as well. For example, we know that plant species loss leads to lower plant productivity in hay meadows and forests. But how species extinctions at one level in the food web might affect ecosystem functions at other levels has rarely been studied. My work will improve the knowledge base of dramatically understudied tropical diversity and of microfaunal and 'brown' (decomposition-based) food webs. In a more general sense, identifying the mechanisms maintaining natural diversity will ultimately contribute to a better protection of species and potentially to a halt in their decline. In addition, by studying effects of species loss on ecosystems this study will help to predict and alleviate negative consequences of species extinctions. Because most ecosystems provide functions that are essential to humans, this research will ultimately benefit us. The model systems of this study were bromeliads in Costa Rica. These plants accumulate water in their leaf-formed tanks, which is inhabited by a number of species of aquatic algae, microscopic animals (microfauna) and larger insect larvae that help the bromeliad to decompose waste material and acquire nutrients. By conducting controlled experiments with natural bromeliads I examined general mechanisms allowing species to coexist and thus maintaining the structure of communities and their diversity. Furthermore, I quantified nutrient flows in the system and measured effects of species loss at high levels (predatory insect larvae) and low levels (resources) of the bromeliad food web on species interactions and nutrient transfer to the plant. More details can be found here: http://www.zoology.ubc.ca/person/petermann
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