SS3.21 Deconstructing Rivers: The Ecological, Geomorphic, and Social Consequences of Dam Removal
Date: Thursday, June 13, 2002
Time: 11:00:00 AM
Location: Colwood
 
OrrCH, Center for Limnology, University of Wisconsin-Madison, Madison, USA, csorr@students.wisc.edu
Stanley, E, H, Center for Limnology, University of Wisconsin-Madison, Madison, USA, 
 
VEGETATION RECOVERY ON FORMER IMPOUNDMENTS DURING THE FIRST 46 YEARS FOLLOWING DAM REMOVAL
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Currently, little information exists about vegetation colonization and development in former impoundments following dam removal. We took advantage of a long history of multiple dam removals in Wisconsin and used a 'space for time' substitution to determine rates and patterns of vegetation establishment on exposed reservoir sediments. Surveys were conducted at 14 sites where dams had been removed between 6 months and 46 years ago. All sites showed almost complete vegetation cover and very little exposed substrate. Species diversity was lower (mean = 24 spp., range = 11-43) and more variable at sites within 5 years of removal relative to sites in which the dam was removed >25 years prior (mean = 36 spp., range = 29-43). Trees were present in 50-88% of all plots in older sites, but only in 2-16% at newer sites. Succession on these sites is progressing towards riparian forest communities, however it may be 25 years or longer before a new removal site resembles a natural riparian ecosystem.