Long-term changes in community composition and exotic species invasion in a restored wetland in North Carolina
Abstract
Wetland systems are highly productive and provide an estimated $33 trillion per year
in ecosystem services. However, wetland ecosystems are one of the most anthropogenically
altered natural systems in the United States, with an estimated 342,700 acres of tidal
and freshwater wetlands drained and developed in North Carolina alone. Wetland restoration
is a growing industry in the United States, but parameters of restoration success
are often poorly defined with few clear baselines available for comparison. One commonly
used metric is the persistence of planted vegetation and species diversity.
This study surveys a restored wetland in Durham, North Carolina to determine whether
the site has successfully maintained robust species diversity seven years after restoration.
Particularly, this study investigates whether increased species diversity has successfully
resisted invasion by Japanese Stiltgrass (Microstegium vimineum). The first goal
was to determine whether plots with higher species diversity had less Microstegium
biomass. The second goal was to find what the changes in plant community dynamics
have been over time. Then, the current plant community was analyzed by comparing
the persistence and abundance of the originally planted species with new species that
have invaded subsequent to restoration. The third and final goal was to determine
whether edge effects are affecting the community composition.
The results indicate that there was no statistically significant difference in Microstegium
biomass weights between the four diversity treatments of 0, 1, 4 or 8 planted species.
A total of 40 species including Microstegium were found in the plots, including 32
new species, eight of which were invasive species and four were obligate wetland species.
A comparison of species importance by plot presence and total biomass indicated that
Microstegium was by far the most abundant species at the site, but many originally
planted species and new native species have persisted and spread. Edge effects were
evident, although not statistically significant, for new non-invasive species. It
appears that edge effects are not strongly influencing the spread of Microstegium.
This study contains several suggestions for further study and Microstegium management
strategies, including the selection of competitive native species, prioritizing active
restoration over natural species recruitment, and continued monitoring over time.
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Master's projectPermalink
https://hdl.handle.net/10161/5283Citation
Edwards, Tiffany Ara (2012). Long-term changes in community composition and exotic species invasion in a restored
wetland in North Carolina. Master's project, Duke University. Retrieved from https://hdl.handle.net/10161/5283.Collections
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