The invasion and spread of the emergent wetland plant Phragmites australis in a Lake Erie coastal wetland.
Whyte, Robert*,1, Klarer, David*,2, 1 California University, Pennsylvania, California, PA2 Ohio Department of Natural Resources, Huron, OH
ABSTRACT- Numerous studies have documented the invasion of wetland plants yet few have tracked the invasion process from its early stages to subsequent large-scale plant community changes. Using a combination of low altitude aerial photography and ground surveys we tracked the spread of Phragmites australis in the Old Woman Creek National Estuarine Research Reserve, a 60 hectare Lake Erie coastal wetland. A shift from a mixed-emergent plant community to dominance by Phragmites, both in mixed vegetation and in monotypic beds, was documented in the aerial photographs for the period 2002-2005. Phragmites currently occupies 30% (11 hectares) of the lower wetland and is also a significant component of the emergent mixed community which covers another 45% of the lower wetland. Declining water levels in Lake Erie and in the adjacent wetland from 1999 onward provided a foothold for several opportunistic species as well as causing a shift in the existing macrophyte community composition. The dominant floating-leaved Nelumbo lutea (American water lotus), the major species in the wetland from the late 1970s through 1999 was replaced by emergent species. Phragmites first appeared in the wetland in the 1980s establishing small stands on and around the beach. By the late 1990s Phragmites had spread all along the shoreline, yet remained a minor component of the overall vegetation. Since the late 1990s the Old Woman Creek wetland has shifted from a predominantly open water system to a shallow water emergent system. Water level fluctuations play an important role in Great Lakes coastal wetland plant community dynamics.
Key words: Lake Erie wetlands, Phragmites, plant community dynamics
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