FEEDBACKS of NITROGEN CYCLING and INVASION with the NON-NATIVE PLANT, <italic>MICROSTEGIUM VIMINEUM</Italic>, in RIPARIAN WETLANDS

dc.contributor.advisor

Richter, Daniel D.

dc.contributor.author

DeMeester, Julie E.

dc.date.accessioned

2009-05-01T18:26:48Z

dc.date.available

2009-05-01T18:26:48Z

dc.date.issued

2009

dc.department

Environment

dc.description.abstract

Invasive species are rapidly expanding in riparian wetlands while concurrently anthropogenic causes are increasing nitrogen (N) into these ecosystems. Microstegium vimineum (Microstegium) is a particularly abundant invasive grass in the Southeast United States. To evaluate impacts of Microstegium on both plant diversity and N cycling in a riparian floodplain, paired plots of Microstegium hand-weeded and unweeded were established for three years. Plots without Microstegium increased from 4 to 15 species m-2 and 90% of the newly establishing species were native. The Microstegium community accumulated approximately half the annual N in biomass of the diverse community, 5.04 versus 9.36 g-N m-2 year-1, respectively (p=0.05). Decomposition and release of N from Microstegium detritus was much less than in the diverse community, 1.19 versus 5.24 g-N m-2 year-1. Rates of soil N mineralization estimated by in-situ incubations were relatively similar in all plots. While Microstegium invasion appears to greatly diminish within-ecosystem circulation of N through the under-story plants, it might increase ecosystem N losses through enhanced denitrification (due to lower redox potentials under Microstegium plots). Microstegium removal ceased in the fourth growing season and formerly weeded plots increased to 59% (± 11% SE) Microstegium cover and species richness decreased to <8 species m-2.

To learn how Microstegium responds to increased N, we conducted a greenhouse competition experiment between Microstegium and four native plants across an N gradient. There was a unique competition outcome in each species combination, yet Microstegium was most dominant in the high levels of N.

Last, we disturbed a floodplain similar to wetland restoration disturbance and tracked available N. We also established a native community of plants with and without Microstegium in three levels of N. Disturbance to the floodplain dramatically increased inorganic N, especially in the form of NO3 which was five times higher in the disturbed floodplain than the undisturbed floodplain. N levels remained elevated for over a year. Microstegium was N responsive, but did not show negative effects to the planted vegetation until the second year. Ironically, restoration activities are increasing available N, and favoring invasive species which in turn detracts from restoration success.

dc.format.extent

4618705 bytes

dc.format.mimetype

application/pdf

dc.identifier.uri

https://hdl.handle.net/10161/1129

dc.language.iso

en_US

dc.subject

Biology, Ecology

dc.subject

Environmental Sciences

dc.subject

Biogeochemistry

dc.subject

Competition

dc.subject

Diversity

dc.subject

Microstegium vimineum

dc.subject

Nitrogen cycling

dc.subject

Restoration

dc.subject

Riparian wetlands

dc.title

FEEDBACKS of NITROGEN CYCLING and INVASION with the NON-NATIVE PLANT, MICROSTEGIUM VIMINEUM, in RIPARIAN WETLANDS

dc.type

Dissertation

Files

Original bundle

Now showing 1 - 1 of 1
Loading...
Thumbnail Image
Name:
D_DeMeester_Julie_a_200904.pdf
Size:
4.4 MB
Format:
Adobe Portable Document Format

Collections