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How Do Extreme Climate Events Affect Plant/Soil Interactions in Agroecosystems?

Description: Das Projekt "How Do Extreme Climate Events Affect Plant/Soil Interactions in Agroecosystems?" wird vom Umweltbundesamt gefördert und von Universität Zürich, Geographisches Institut durchgeführt. 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

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Origin: /Bund/UBA/UFORDAT

Tags: Bodenvegetation ? Eiche ? Wasserwiederverwendung ? Weizen ? Tierhaltungsanlage ? Bodennährstoff ? Vegetation ? Saumgesellschaft ? Organischer Kohlenstoff ? Zürich ? Bodenkohlenstoff ? Durchschnittstemperatur ? Bodenschätze ? Fischer-Tropsch-Verfahren ? Kohlenstoff ? Nährstoff ? Skigebiet ? Stickstoff ? Wiese ? Blei ? Schweiz ? Wertstoffsack ? THM-Prozess ? Photosynthese ? Fracking-Fluid ? Bodenwasser ? Ernte ? Gesamtkohlenstoff ? Grünland ? Klimavariabilität ? Landwirtschaftliche Nutzung ? Organisches Material ? Topographie ? Dürre ? Wärmehaushalt ? Wasserreinigung ? Agrarökosystem ? Pflanzenwurzel ? Aufbereitungstechnik ? Grünlandwirtschaft ? Staude ? Technosol ? Ackerboden ? Mitteleuropa ? Gelöster organischer Kohlenstoff ? Wertstoffbehälter ? Alpen ? Klimaforschung ? Phytomasse ? Rohstoff ? Studie ? Systemanalyse ? Gewässerzustand ? Instandhaltung ? Werkzeugmaschine ? Boden ? Hochgebirge ? Biologische Aktivität ? Weideland ? Ökosystemforschung ? Berechnungsverfahren ? Beobachtungsfläche ? Beschlagnahme ? Flächennutzung ? Management ? Bewässerung ? Beweidung ? Mesoklima ? Bodenökosystem ? Oberirdische Biomasse ? Wasserknappheit ? Artenvielfalt ? Ressource ? Erdoberfläche ? Ressourcennutzung ? Produktivität ? Vegetationsgrenze ? Globale Aspekte ? Lagerung ? Verkrautung ? Versuchsanlage ? Heizung ? Abdeckung ? CCS-Technologie ? Biomasse ? Klima ? Ökosystem ? Klimawandel ? Klimafaktor ? Adsox-Verfahren ? Produktivitätssteigerung ? Mittel ? Saarberg-Hölter-Verfahren ? Temperaturerhöhung ? Bram-Verfahren ? Stall ? Wechselwirkung ? Stoffwechselaktivität ? Schlammwasser ? Bricollare-Verfahren ? Handlungsorientierung ? Lohnform ?

License: cc-by-nc-nd/4.0

Language: Deutsch

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Time ranges: 2005-04-01 - 2009-05-31

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