Graduate Program

Biological Sciences

Degree Name

Master of Science (MS)

Semester of Degree Completion

Summer 2020

Thesis Director

Scott J. Meiners

Thesis Committee Member

Zhiwei Liu

Thesis Committee Member

Ann H. Fritz

Abstract

Introduced exotic species have a tendency to become invasive and impact local biological communities. Invasions often impact community attributes such as cover and species richness, but these factors may also regulate patterns of invasion. In such cases, impacts may be dependent on the invasion context. We used data from the Buell-Small Succession Study, a long-term permanent plot study in the piedmont region of New Jersey, to document context dependency in invasion. To do this, we analyzed the factors that affected the colonization and growth of four invasive species, Alliaria petiolata, Lonicera japonica, Microstegium vimineum and Rosa multiflora, as well as the impacts of these invasions on the community.

In Lonicera japonica and Microstegium vimineum, it was found that more species rich plots were significantly more likely to become invaded, whereas increased species richness inhibited the likelihood of successful invasion by Alliaria petiolata. The establishment of Rosa multiflora was not affected by variation in species richness. Species richness and total vegetative cover did not significantly affect the growth/spread within successfully invaded plots. Life forms (trees, forbs, lianas, or shrubs) and co-occurring dominant species were linked to the spread of some invasive species. Species richness of the community was significantly affected by A. petiolata, L. japonica, and R. multiflora, within temporally explicit analyses (change over time). The temporally static analysis indicated that species richness was significantly impacted by each of the four invaders with some showing marked differences from the temporally explicit analysis. Total vegetative cover was similarly affected by species invasion. In each of these case studies, the context of invasion was necessary in understanding their ultimate impacts. The perceived impacts of invasion may be offset or amplified by the factors which regulate invasion. My data suggest that analyses from single-time studies may provide inaccurate estimates of invasion impacts.

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