Poster, Jahrestagung der Arbeitsgemeinschaft für stabile Isotope (ASI), Köln / Cologne: 04.10.2010 - 06.10.2010
Abstract:
Conservation of grasslands carbon storage characteristics is desirable in times of climate change. But ecosystem function and species composition of temperate grasslands are likely to respond to precipitation change (IPCC). As long-time climate measurements suggest precipitation deficits in Southern German low mountain ranges mainly during spring, FORKAST project investigates local carbon fluxes between atmosphere, biosphere and soil during artificially induced drought periods. Tracing of 13C after pulse labelling - accompanied by micrometeorological flux measurement techniques (eddy covariance - EC and hyperbolic relaxed eddy accumulation - HREA) turned out as suitable approach. A decrease of organic matter input and lower turnover rates are expected at drought plots, compared to normal precipitation plots. Combining long-time EC (>1year) and chamber measurements of CO2-flux renders determination of drought influences on larger scale fluxes possible. Species specific changes in photosynthetic activity and modified assimilate translocation characteristics from leaves to roots and soil are also expected. This can be a basis to evaluate stability and resilience of the species composition of the ecosystem under influence of extreme climate conditions. Another great challenge is to evaluate the influence of atmospheric (13)CO2 fluxes on tracer translocation in biosphere and soil. This issue will also be discussed.