To add to the thread, I suppose these dams are no more than 150 years
old at most ? So the wetlands created by placing the dam are not very
old, thereby quite possibly not as species-rich as a natural wetland
Furthermore, the original (pre-dam) ecosystem being a running water
system, its restoration can have greater ecological value, since there
are few locations on the landscape where streams can naturally exist.,
ie, basically along local topographic lows. There is also the river
continuum concept whereby removal of artificial barriers to water flow
can have an impact far beyond the immediate stream reach.
However its possible that these particular artificial wetlands could be
important sites of refuge for wetland spp that managed to arrive there
-- as Sharif mentions, it would be good to actually examine the wetlands
in question, and then decide. Generally speaking, stream restoration
could provide more ecological diversity, as its technically easier to
create a wetland elsewhere (in theory at least), but the benefits and
costs could vary from case to case.
Cheers
Amartya
Sharif Branham wrote:
Hello Andy,
I think the question should be about the quality of the wetlands that are being replaced. Wetlands that are created as a result of roads or other engineered surfaces are not equal to a natural wetland as far as habitat value is concerned. One could do an analysis of the wetland that is to be displaced by breaching the dam to see if the quality of the habitat that will be lost is equal, less than or greater than the habitat that will be enhanced by breaching the dam. You could consider the quantity and diversity of the species that benefit from each habitat type. You could even look at ecological services being provided by the wetlands versus what will be gained by breaching the dam. I hope that helps you get at the essence of the argument.
Sharif> Date: Wed, 9 Apr 2008 12:50:53 -0400> From: [EMAIL PROTECTED]> Subject: [ECOLOG-L] wetland acreage> To: [email protected]> > I have been discussing the merits of stream restoration with some > colleagues and I've been fussing over the potential loss of wetlands > as a result of the removal of dams. My stream-oriented friends have > been asking why I've been worried about the loss of what amounts to > artificial wetlands in the first place? Aside from the fact that > they're typically considered jurisdictional, it got me wondering if > we (collectively) have any idea whatsoever how many wetlands in the > landscape are artificial? In other words, how many wetlands exist > because of human activities, such as roads, railroads, and the like? > (Let's keep mitigation, stormwater, and treatment wetlands out of the > discussion for now.) Anyone have a clue?> > Thanks.> > Andy Cole> > > > Charles Andrew Cole, Ph.D.> Associate Director> Center for Watershed Stewardship>!
Penn State University> 301a Forest Resources Laboratory> University Park, PA 16802>
814-865-5735> [EMAIL PROTECTED]> > http://www.larch.psu.edu/watershed/home.html
_________________________________________________________________
Use video conversation to talk face-to-face with Windows Live Messenger.
http://www.windowslive.com/messenger/connect_your_way.html?ocid=TXT_TAGLM_WL_Refresh_messenger_video_042008
