Land-use intensification in grassland ecosystems: effects from leaf to ecosystem
Laura Rose
Department of Ecology and Ecosystem Research, University of Goettingen, Germany
In the last 50 years, land-use changes in temperate grassland ecosystems occurred either by land-use intensification, i.e. increased fertilization, cutting frequency and stocking rate, or by abandonment of non-profitable sites mostly on low productive soils. Such land-use changes can have profound effects on the species composition, the amount of standing and produced biomass, and on biogeochemical cycles. I am going to present results from the GrassMan experiment, an interdisciplinary meadow experiment at the University of Göttingen, which is designed to investigate the effects of plant biodiversity, fertilizer application and different cutting frequencies on several aspects of grassland functioning.
Fertilizer application and alterations of the cutting frequency severely affect functional leaf traits: NPK-fertilization leads to generally higher leaf-level water use efficiency (WUE), accompanied by an increase in the specific leaf area and leaf nitrogen concentration. Cutting effects are more species specific. Besides these effects on leaf trait values, fertilization additionally alters the interspecific relationships between leaf traits.
Although the increase in leaf-level water use efficiency with fertilization is mirrored by an increase in WUE on the stand level, fertilization leads to higher evapotranspiration rates and thereby decreases ground-water recharge. This is mostly attributed to the higher amount of biomass produced in fertilized compared to unfertilized meadows. Irrespective of its positive effect on aboveground biomass production, fertilization increases nitrogen leaching.
Although the increase in leaf-level water use efficiency with fertilization is mirrored by an increase in WUE on the stand level, fertilization leads to higher evapotranspiration rates and thereby decreases ground-water recharge. This is mostly attributed to the higher amount of biomass produced in fertilized compared to unfertilized meadows. Irrespective of its positive effect on aboveground biomass production, fertilization increases nitrogen leaching.
