Comparison of soil chemistry and microbial communities that inhabit the rhizosphere of native and non-native grasses of the Lower Rio Grande Valley

Non-native grasses can modify the soils they invade. This study investigated microbial variation among native and non-native grasses in the Lower Rio Grande Valley. We hypothesized that rhizospheres of non-native grasses would support a higher density of microorganisms; therefore microbial communities of invasive plants would exploit more carbon sources than those of native plants. A second hypothesis stated that Streptomyces bacteria from the rhizosphere of non-native grasses would be better competitors. Samples of grasses, and soil from their respective rhizospheres were obtained in Arroyo City, TX. Results indicated a higher bacterial colony density, total activity and number of substrates utilized in non-native grasses before transplants, but no significant difference after. Additionally, only pH was significantly different before and after transplants. Furthermore, frequency and zone of inhibition of Streptomyces from native and non-native grasses were not significantly different. Such changes the soil can promote invasion of these and other grasses.