The diversity-productivity relationship in a permanent temperate grassland: negative diversity effect, dominant influence of management regime

Background: Agricultural intensification has transformed most grasslands of Central Europe from non-intensive to highly intensive management during the last 50 years, resulting in large reductions of species diversity. This impoverishment has raised concern with regard to ecosystem functions. Positive diversity effects on productivity have been found in experiments with synthetic grasslands but were rarely confirmed in semi-natural grasslands in the field. Aims: Our objective was to investigate the diversityproductivity relationship independently from management effects in mature grassland. Methods: We conducted a three-factorial experiment (fertilisation, mowing frequency, diversity; n?=?6) in a permanent grassland to disentangle effects of management intensity and diversity on above-ground biomass (AGB), fine root biomass and root distribution patterns. Herbicides were applied to increase the diversity gradient across the plots. Results: While fertilisation had a strong positive effect on AGB and the cutting frequency a minor one, AGB was negatively related to species richness. Root biomass and distribution gave no indication of below-ground complementary resource use. Conclusions: The N-driven productivity increase since the 1950s is by far more influential on above-ground productivity than any diversity effect. Field manipulation studies in mature communities are needed to understand the productivitydiversity relationship in grasslands under changing land use.