Grantee Research Project Results

Potential Edaphic Effects of Buffelgrass (Pennisetum ciliare) Invasion: From Microbial Function to Ecosystem Alteration

EPA Grant Number: U916211
Title: Potential Edaphic Effects of Buffelgrass (Pennisetum ciliare) Invasion: From Microbial Function to Ecosystem Alteration
Investigators: Johnson, Mari-Vaughn V.
Institution: Texas A & M University - Kingsville
EPA Project Officer: Hahn, Intaek
Project Period: January 1, 2003 through January 1, 2006
Project Amount: $83,658
RFA: Minority Academic Institutions (MAI) Fellowships for Graduate Environmental Study (2003) RFA Text |  Recipients Lists
Research Category: Biology/Life Sciences , Fellowship - Natural and Life Sciences , Academic Fellowships

Objective:

The objective of this research project is to investigate the edaphic effects of native and exotic grasses in South Texas (the exotic invasive grass Pennisetum ciliare and the native grass Heteropogon contortus). Exotic plant species invasions have been shown to alter ecosystem properties. They may alter levels of plant and microbial biodiversity, as well as soil functions. Decomposition rates and contributions of native and exotic plant litter may vary greatly. Thus, plant invasions may profoundly affect ecosystem functioning.

Approach:

One randomized complete block greenhouse study is underway. In this study, we are addressing species-specific efficiency of N and P acquisition and assimilation. Concurrently, we are conducting a randomized complete block field experiment to determine if soil properties differ under the two species. Another randomized complete block field experiment addresses species-specific decomposition dynamics. A fourth greenhouse experiment with a randomized complete block design will be used to further probe for evidence of exotic facilitation or positive feedback loops through soil alteration. We anticipate finding that the exotic grass P. ciliare differs from the native H. contortus in terms of contributions to the N cycle. If an individual species affects N mineralization and availability, competition for N by other plant and microbe species may lead to positive or negative feedbacks between the processes controlling species composition and ecosystem processes such as N cycling. These findings would signify that the invader may have long-term consequences on ecosystem function, as it may create an alternative stable state.

Supplemental Keywords:

fellowship, Pennisetum ciliare, Heteropogon contortus, exotic grass, native grass, invasive species., RFA, Scientific Discipline, Ecosystem Protection/Environmental Exposure & Risk, Monitoring/Modeling, Habitat, exotic grass species, biodiversity, bunch grass, community composition, invasive plant species, habitat dynamics, ecological consequences, community genetic diversity, soil chemistry, landscape context

Relevant Websites:

2004 STAR Graduate Fellowship Conference Poster (PDF, 1p., 94.7KB, about PDF)

Progress and Final Reports:

2003

2004

Final