In this proposal the P.I. develops a mechanistic model of competition that makes predictions about how resource use by plants influences both individual competitive ability and the population-level outcome of competition along productivity gradients. The model is based on separating two components of competitive ability: ability to deplete resources and ability to tolerate depleted resources. Using these two types of plant- resource interactions to predict the outcome of net plant-plant interactions is complex because the relative sizes of interacting plants determine whether good depletors or good tolerators are the superior competitors and because depletion and tolerance abilities are determined by different plant traits. The investigators develops specific predictions about these relationships and describe experiments to test them in a desert grassland community such models should have significant implication for many plant communities, included those endangered worldwide.
