title: Soil microbes drive the classic plant diversity-productivity pattern.
abstract: Ecosystem productivity commonly increases asymptotically with plant species diversity, and determining the mechanisms responsible for this well-known pattern is essential to predict potential changes in ecosystem productivity with ongoing species loss. Previous studies attributed the asymptotic diversity-productivity pattern to plant competition and differential resource use (e.g., niche complementarity). Using an analytical model and a series of experiments, we demonstrate theoretically and empirically that host-specific soil microbes can be major determinants of the diversity-productivity relationship in grasslands. In the presence of soil microbes, plant disease decreased with increasing diversity, and productivity increased nearly 500%, primarily because of the strong effect of density-dependent disease on productivity at low diversity. Correspondingly, disease was higher in plants grown in conspecific-trained soils than heterospecific-trained soils (demonstrating host-specificity), and productivity increased and host-specific disease decreased with increasing community diversity, suggesting that disease was the primary cause of reduced productivity in species-poor treatments. In sterilized, microbe-free soils, the increase in productivity with increasing plant species number was markedly lower than the increase measured in the presence of soil microbes, suggesting that niche complementarity was a weaker determinant of the diversity-productivity relationship. Our results demonstrate that soil microbes play an integral role as determinants of the diversity-productivity relationship.
authors: Department of Biological Sciences, University of Wisconsin, P.O. Box 413, Milwaukee, Wisconsin 53201 USA. Schnitzer@uwm.edu
authors: Stefan A
authors: SA
authors: Schnitzer
authors: John N
authors: JN
authors: Klironomos
authors: Janneke
authors: J
authors: Hillerislambers
authors: Linda L
authors: LL
authors: Kinkel
authors: Peter B
authors: PB
authors: Reich
authors: Kun
authors: K
authors: Xiao
authors: Matthias C
authors: MC
authors: Rillig
authors: Benjamin A
authors: BA
authors: Sikes
authors: Ragan M
authors: RM
authors: Callaway
authors: Scott A
authors: SA
authors: Mangan
authors: Egbert H
authors: EH
authors: van Nes
authors: Marten
authors: M
authors: Scheffer