Scales and arrangements of large wood in first- through fifth-order streams of the Blue Ridge Mountains

Abstract

Large wood frequency and volume were examined as a function of landscape characteristics at different spatial and temporal scales in 50 reaches of the Upper Little Tennessee River basin with drainage areas ranging from 0.3 to 30.1 km2. Riparian forest cover was described laterally at the reach scale and longitudinally 1 km upstream in all tributaries. Riparian cover was analyzed with geomorphic and additional landscape variables to isolate factors that most influence wood in streams. Forested area immediately surrounding the reach was the strongest predictor of wood frequency and volume, although upstream riparian cover can explain additional variation in wood distributions. An optimal forested buffer width around the stream for large wood was not evident. The relationship between the riparian forest and wood weakens in bigger channels, as fluvial transport of pieces increases. Resurveys demonstrate that large wood is most dynamic in wide, forested reaches and changes function during floods to store sediment and organic matter.