Effects of Typha x glauca Invasion on Nitrogen Fixation in a Great Lakes Coastal Wetland
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Typha x glauca, an invasive hybrid of the broad-leaf (Typha lalifolia) and narrow-leaf cattail (Typha anguslifolia), poses a serious threat to Great Lakes region wetlands not only due to its aggressive growth and expansion but also because of the filling in of wetlands where Typha x glauca is present. Extremely high levels of nitrogen have previously been found in the soils of T. glauca-infested marshes, and this was theorized to be due to elevated rates of N-fixation in T. glauca soils. The purpose of this study was to quantify the rates o fN-fixation in the soils of T. glauca-dominated communities and compare them to the N-fixation rates in native plant communities. N-fixation was measured using the acetylene reduction method on soil core samples collected in June, July and August of 2007 in three different plant zones: Typha zone (99% T. glauca present), Transition zone (330/0 T. glauca present) and Native zone (No T. glauca). N-fixation was found to be higher in the Typha zone than in the Transition and Native zones, and N-fixation was also found to progressively decrease from June to August in the Typha zone.