| Popis: |
Although riparian forests are well-known to improve water quality by filtering sediment, very little is known about how this sediment impacts biological processes. This study compares several riparian forests associated with ephemeral streams receiving different sediment loads from the erosion of unpaved forest roads at Fort Benning, GA. The objective of this study was to determine how increasing sedimentation affects forest health and productivity, specifically net primary production (NPP), nutrient cycling, and foliar decomposition. Current sedimentation rates (from June 2004 to June 2005) were estimated from slightly negative in reference areas to over 8 cm yr-1 in highly disturbed areas. Above- and below-ground net primary productivity (NPP), N mineralization, and foliar decomposition were compared among areas receiving varying sedimentation rates. NPP averaged between 2361 and 1172 g m-2 yr-1 on reference and highly disturbed plots, respectively. Nutrient contents in fine roots and litterfall decreased with increasing sedimentation rates. Nitrogen mineralization rates were highest in areas receiving moderate sedimentation. No clear relationship was found between decomposition and sedimentation rates. Sedimentation rates between 0.2-0.3 cm yr-1 were associated with declines in forest productivity and nutrient (C, N and P) contents in plant tissues. Consequently, erosion control practices should be implemented to protect riparian forests from the impacts of sediment deposition. |
