Organic matter processing and opportunities for stream mitigation in an intensively mined West Virginia watershed.

摘要

Mountaintop removal/valley fill mining is a controversial process that may have far-reaching impacts on central Appalachian watersheds. Our project sought to quantify spatial and temporal variation in organic matter processing within Pigeon Creek, an intensively mined sub-watershed of the Tug Fork River in southern West Virginia. Our objectives were to: (1) quantify variation in organic matter retention and decomposition among streams differing in size (drainage area), gradient, and structural complexity; and (2) quantify the effect of valley fills on stream flow, water chemistry, organic matter processing, and benthic invertebrate colonization of detritus packs in 1 st order perennial streams. Our study area consisted of 26 sites distributed across a wide range of stream sizes (ephemeral channels to large perennial streams). Four of the small perennial sites were located below large valley fills and were paired to four undisturbed sites. At each site we quantified water temperature (continuous), stream flow (continuous), habitat quality and complexity, water chemistry (seasonal), artificial leaf and stick transport (seasonal), leaf pack decomposition (seasonal), and invertebrate colonization (seasonal). Organic matter decomposition rates were variable, but unrelated to any environmental factors that we measured. Drainage area, channel complexity, and mining had a significant interactive effect on transport distance of leaves and sticks. Sites below valley fills had enhanced flow levels, but this did not result in higher transport levels. Also, sites below valley fills had significantly higher conductivity, but this did not produce a significant effect on organic matter decomposition or on benthic invertebrate colonization of leaf packs. These results add to our understanding of complex interactive effects of mining on stream ecosystem functions and our ability to compensate for lost headwater functions through restoration actions downstream.