All plants live with a huge number and diversity of tiny organisms, called microbes. Some help plants by providing nutrients, whereas others can have negative effects like causing disease. Ecologists now believe that some microbes in the soil can determine which plant species can grow in a particular place and how common those plants can become. Thus, microbes may be an invisible force determining the health of many plants, including those we depend on for food. Practically all microbes are sensitive to changes in the environment. This is important because changes in weather -- decreased rainfall, for example -- could greatly affect which microbes thrive in the soil and therefore the abundance and distribution of plants. Plants, in turn, may determine the presence or absence of certain microbes in the soil, thereby creating a complicated situation in which plants and microbes affect each other's success. This idea of "plant-soil feedback" is a relatively new way of thinking about what plants need and their living arrangements with microbes. This research will test how sensitive soil microbes are to soil moisture and, in turn, how that sensitivity may impact plants. The investigator will compare plant and microbial communities along a gradient of rainfall in Texas and will explore how native and non-native plant species differ in their interactions with microbes along that gradient. Results of this work will have direct applications for predicting and mitigating the effects of drought on an economically and culturally important ecosystem, Texas grasslands. This research will also provide training opportunities for the next generation of scientists, including students from underrepresented groups at the University of Houston, a Hispanic Serving Institution. The investigator will share her experiences with children in under-served public schools and will lead educational workshops through local non-profit agencies.<br/><br/>This project has three major components. First, a greenhouse experiment will test how water availability influences plant-soil feedback among native and non-native plant species. The experiment will be paired with root microscopy and DNA sequencing to identify candidate microbial taxa underlying plant-soil feedback effects, a critical, but often lacking step in generalizing plant-soil feedback responses. Second, a precipitation-manipulation experiment in the field will test, for the first time, whether changes in plant-soil feedback can predict changes in plant community composition in the different precipitation treatments. Third, a reciprocal soil transplant experiment will test for generality in plant-soil feedback responses across a natural precipitation gradient in Texas, which will provide insights into whether plant-soil feedback responses to climate may depend on historical climate legacies. Given plant-soil feedback theory's success at integrating plant-microbe interactions into the framework of plant community ecology, deeper insights into the factors that influence plant-soil feedback may transform our understanding of how plant communities are structured and plant diversity is maintained.<br/><br/>This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.