Mutualism and BEF
Biodiversity-ecosystem function (BEF) studies show that ecosystem function tends to increase with plant diversity. However, a lot of variation exists around the observed BEF patterns. Legumes may contribute significantly to variance in the results of BEF experiments, because access to atmospheric N through their rhizobial symbionts can differentiate legume niches and relative fitnesses, two processes thought to underlie the BEF relationship. We are experimentally examining the biotic processes that underlie the niche and relative fitness differences of legume species from each other and from non-legumes to test the hypothesis that these differences can explain variation in BEF patterns. Additionally, as carbon and nitrogen form the basis of the symbiosis between legumes and their rhizobial mutualists, we are examining how legumes and rhizobia respond to long-term, chronic increases in CO2 and soil N.