Experimental plant ecology
The main focus of the Experimental Plant Ecology Department is the climate change impact research. In long-term field experiments at the “Environmental Monitoring and Climate Change Impact Research Station Linden” we study plant and ecosystem reactions on climate change. In our Phenological Garden we observe changes in the plant phenology as a reaction on higher air temperature. In climate change manipulation experiments we investigate the reactions of plants and ecosystems on elevated atmospheric CO2 concentrations and higher air temperature. Since 1998 grassland plots are exposed to +20% higher CO2 concentrations compared to ambient (Giessen FACE = Free Air CO2 Enrichment) and we investigate changes in the species composition, plant growth, ecosystem fluxes of carbon and nitrogen, including greenhouse gas fluxes of CO2, CH4 and N2O, and many other parameters. In an additional experiment the temperature of soil and plant surfaces was heated (IR-Lamp Experiment). In an actual experiment we increase the air temperature directly in combination with elevated CO2 concentration and study the ecosystem responses (Giessen T-FACE = air Temperature warming and Free Air CO2 Enrichment).
One important result of the Giessen FACE is the doubling of N2O emissions under elevated CO2 and therefore one important research focus is to understand the responsible processes and nitrogen transformations in the soil, which is part of the research group DASIM (Denitrification in Agricultural Soils: Integrated control and Modelling at various scales).
In a Biochar Field Experiment we test if CO2 assimilated by plants and transformed into a stable carbon form as plant charcoal can be established as a climate change mitigations strategy to reduce the atmospheric CO2 concentration storing the stable carbon form long-term in agricultural soil. Additional investigations on anthropogenic Amazonian Terra Preta Soils are conducted for a better understanding of the positive effect of black carbon (plant charcoal) in tropical soils. Analogous, we study temperate historical killen soils created through charcoal burning.
Additional research questions are the investigation of Nutrient- and Energy-Exchange between the Phytosphere and the Atmosphere, as the atmospheric N deposition or the exchange of ozone.