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Initial responses of littoral vegetation to restored flow in the Kissimmee River.
Bousquin, Stephen*,1, 1 Kissimmee Division, South Florida Water Management District, West Palm Beach, Florida, USA
ABSTRACT- Prior to channelization of the Kissimmee River, the extent and species composition of littoral plant communities were typical of a low-gradient lotic environment. Aquatic vegetation was limited, likely primarily by flow, to narrow littoral zones dominated by emergent species. With the completion of channelization of the river in 1971 and diversion of flow to the canal, remnant channels became virtually stagnant pools. Littoral vegetation beds expanded toward mid-channel areas and cover of floating and mat-forming species increased relative to cover of emergent species. In some cases, extensive vegetation beds dominated by exotic floating species completely spanned channels. To monitor responses of littoral vegetation to restoration of flow, we collected species composition and vegetation bed data twice annually (winter and summer) from 1998-2003 at permanent transects in channels slated for flow restoration and at control transects. Data were examined for each of three time intervals: a pre-restoration baseline period (February 1998-June 1999), an initial response period during which flow was reestablished intermittently (August 1999-March 2001), and a post-construction period following reestablishment of continuous flow (August 2001-March 2003). Mean vegetation bed widths on three channel curvature categories (inner bends, outer bends, and straight reaches), mean relative cover of floating and mat-forming plant species, and mean percentage of channel that was vegetated declined with reestablished flow.
Key words: aquatic vegetation response, river restoration, littoral vegetation, flow restoration