Human activities are concurrently changing both the climate and the diversity of ecological communities, but we know little about how these two drivers of environmental change interactively impact ecosystem functioning. We established a Biodiversity and Climate (BAC) experiment to examine how experimental warming affects perennial prairie plant communities that differ in species number (1, 4 and 16 plant species) and temperature (High Warming +3°C; Low Warming, +1.5°C; and Ambient temperature). Plots have been warmed from 2009-2011 by suspended infrared lamps. In each of 96 subplots, soil temperature was logged continuously throughout the growing season, and soil moisture was measured regularly using surface moisture probes and deep soil TDR. Aboveground biomass and species abundances were determined by annual biomass clipping and sorting, and seasonality of biomass production by NDVI measurements. Belowground biomass, soil C and soil N were also quantified.
Results/Conclusions
Total aboveground biomass significantly increased with both species diversity and warming, with no significant interaction between the two treatments. Warming caused a significant decrease in diversity, with the 16 species plots losing ~1 species. Warming also changed plant community composition, with 3 legumes and one C4 grass species increasing in response to warming. Further, we found that higher diversity treatments buffer the effects of warming on soil temperature and moisture, indicating an interaction between diversity and warming on micro-climate. Due to the longevity of perennial grassland species, we would expect heating effects on nutrient and carbon stores, deep soil moisture, below ground biomass, and further community compositional changes to appear over a longer time period. Based on these results, we predict that warming may have negative effects on overall diversity of plant communities and that this effect may be related to the increased dominance of particular species in warmer conditions.