Theses and Dissertations - UTB/UTPA

Date of Award


Document Type


Degree Name

Master of Science (MS)



First Advisor

Dr. Kristine L. Lowe

Second Advisor

Dr. J. Andrew McDonald

Third Advisor

Dr. Teresa P. Feria


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.


Copyright 2011 Jacqueline Valencia. All Rights Reserved.

Granting Institution

University of Texas-Pan American