Plant-soil feedbacks have recently been implicated in producing profound community consequences. In my dissertation, I combine surveys with experiments to test the importance of feedbacks in a dry grassland system. A feedback is composed of two parts: species effects on the environment and species responses to that altered environmental. One method of estimating species response to soil moisture (an important environmental variable in this dry system) is to measure water-use efficiency (WUE). Results to date suggest that positive feedbacks are common in this grassland. Therefore, I will test the hypothesis that species that produce high moisture environments have low WUE. Knowledge of the WUE of the species in my system will also be used to mechanistically explain the outcome of ongoing transplant performance experiments.