XVI International Botanical Congess

Biodiversity influences N fluxes by differences in plant uptake or supply rates, which both control N retention and losses and, thereby, ecosystem pools. We used an experiment with 147 plots, planted with 1, 2, 4, 6, 8, 12 or 24 grassland species with 20-24 replicates. Biodiversity impacted soil available mineral N, implying that biodiversity impacted N uptake. This was reflected in net primary productivity. We also found changes in litter decomposition and N mineralization, both decreasing with diversity. Total soil C and N pools were only marginally impacted by diversity. Thus, the effect of biodiversity on ecosystem C and N pools and fluxes is mainly a direct result of nutrient uptake and productivity. Although the relative importance of supply influenced by the afterlife of dead plants does reinforce this and increases with time.