By mimicking an invasion of Typha x glauca in experimental mesocosms, I was able to study how this invasive plant impacts a native wetland community and the role its litter plays in its invasion success. I found that post-invasion, Typha x glauca litter had a strong negative effect on density, biomass and species diversity of the native plant community. Typha litter suppressed the native community through the modification of both the physical and the biogeochemical environment. Physical variables, such as soil temperature, fluctuated less and were on average cooler under litter. Light penetration under litter was significantly lower. Chemical variables were also modified; litter led to higher organic nitrogen mineralization rates and higher leaf tissue nitrogen levels. In a litter-bag transplant experiment in Cheboygan Marsh, on the border of Lake Huron, I sought to determine how and why Typha x glauca litter accumulates and persists while native plant litter does not. One key factor contributing to Typha x glauca litter accumulation was far-slower decomposition rates of litter from all plant species in Typha-dominated microhabitats. After 422 days of decay, litter bags in the invaded zone had nearly double the mass of those deployed in the native zone. The microenvironment in the invaded zone was conducive to slow decomposition with an absence of standing water, cooler soils and lower levels of bacterial biomass and productivity. In addition, species-specific traits of Typha x glauca seemed to slow litter decay. Typha x glauca litter has relatively high C:N and low surface area to volume in leaf and stem morphology, both traits likely inhibit bacterial activity and therefore decomposition.
|Advisor:||Tuchman, Nancy C.|
|School:||Loyola University Chicago|
|School Location:||United States -- Illinois|
|Source:||MAI 47/03M, Masters Abstracts International|
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