Date Approved

2012

Degree Type

Open Access Senior Honors Thesis

Department

Biology

First Advisor

Dr. Kristin Judd

Second Advisor

Dr. Gary Hannan

Abstract

Wetlands support high biodiversity. but invasion by the common reed Phragmites australis has reduced plant diversity in wetlands along the Detroit River and throughout the Great Lakes. Phragmites often replaces Typha spp., reducing nesting habitat quality for ducks. Wetland managers often attempt to remove Phragmites, relying mainly on herbicide application and burning to promote germination from dormant seeds in the seed bank. The success of these restoration efforts is at least partially dependant on the diversity of the seed bank. To determine the composition and diversity of the seed banks in wetlands undergoing restoration. soils were collected from four wetland sites located within the Detroit River International Wildlife Refuge (DRI\VR) dominated by Phragmites or Typha and incubated in the greenhouse (Humbug Marsh, Pointe Mouillee, Strong Unit and Fix Unit). Plant species richness was greater than the above ground vegetation species richness. and was lower in the Fix and Strong Units (5 and 7, respectively). but higher in Humbug Marsh (13 in HBT, 21 in HBPR) and Pointe Mouillee (20 in PMP10, 10 in PMT08, 14 in PMT06). The estimated floristic quality assessment index for Humbug Marsh was 10.0 and for Pointe Mouillee, 3 .5. This study suggests that regrowth from the seed bank may provide successful restoration for wetlands within the DRIWR increasing plant richness and diversity. but that the outcome may differ among sites.

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