Interim Responses of Littoral River Channel Vegetation to Reestablished Flow after Phase I of the Kissimmee River Restoration Project

Measurements of littoral vegetation stands and species-level surveys of associated plant communities were made in channels of the Kissimmee River from 1998 through 2008, a period that spanned channelized, non-flowing conditions through 7 years of near-continuous reestablished flow. Dissected by flood control canal C-38 in 1971, the river was virtually without flow until early 2001, when Phase I of the Kissimmee River Restoration Project (KRRP) reestablished flow to a central section of river channel. This study evaluated the effects of reestablished flow on littoral vegetation in river channels as an indicator of system status and progress toward the project goal of ecological integrity. Predictions of vegetation response to reestablished flow included reduction in the width of vegetation stands, and changes in the growth-form composition of littoral stands from near-equal dominance by floating and emergent species to overwhelming dominance by emergent growth forms. Variables included plant cover by species and growth-form, width of vegetation stands, and vegetated percentage of channel. Under the currently incomplete (interim) status of the KRRP, results for littoral vegetation stands indicate trends in the predicted directions of change, and three of four predicted changes have occurred. Vegetation stand widths decreased substantially and littoral plant communities became heavily dominated by emergent species; BACIPS (before-after-control-impact-paired series) analyses indicated significant restoration effects for most littoral stand metrics.