Wednesday, May 28, 2008 - 3:45 PM
494

Stream hydrology and geomorphology influences efficacy of restoration using large wood additions in disturbed coastal plains watersheds

Jack W. Feminella and Richard M. Mitchell. Biological Sciences, Auburn University, 331 Funchess Hall, Auburn, AL 36849

Large woody debris is a critical habitat in sandy coastal plains streams; thus, in disturbed catchments, reduction of instream wood from entrainment/burial by sediment can impact benthic communities. In 2003 we created a series of artificial woody debris dams (sectioned logs from felled riparian trees) to enhance benthic communities in 4 disturbed streams at Fort Benning, GA. Effectiveness of debris dam additions on biotic recovery was quantified over a 3-year post-restoration period using several macroinvertebrate measures.  Increases in biotic integrity from debris dam additions varied greatly among seasons, streams, and measures, resulting largely because of atypically high precipitation/discharge during the post-restoration period, and associated high sedimentation and debris dam burial.  Restored streams with high hydrologic flashiness, unstable stream beds, and associated high burial of debris dams (up to 75% in 6 mo) also were those showing the lowest amount of biotic recovery relative to less flashy streams with more stable channels and lower dam burial. Our data suggest that recovery trajectories in such disturbed streams are a complex function of intersite variation in hydrology and geomorphology. If true, then accurate predictions of effects of restoration may only be possible with an understanding of stream-specific flow regimes and sediment movement dynamics.


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