Wood distribution along streams draining old-growth floodplain forests in Congaree National Park, South Carolina, USA

Abstract

We measured wood volume and other characteristics along a series of instream and floodplain transects in and around Congaree National Park, South Carolina. Seven transects were surveyed at most sites; one within the bankfull channel, and three on each bank, at 10, 50, and 100 m lateral distances, respectively, from the channel. Along each transect we measured piece dimensions, location along transect, orientation, and decay category. We also characterized channel width, drainage area, vegetation type, average forest basal area, and inundation category for each transect. Forest transects > 100 m from a channel were also surveyed. Instream wood loads for unmanaged channels draining old-growth forests were 102–178 m 3/ha, which is lower than most instream wood loads documented for old-growth temperate forests. We attribute the lower wood loads to the combined effects of high transport capacity and rapid decay. Floodplain wood loads are lowest close to the channel but increase with distance, reaching comparable values (up to 172 m 3/ha) at distances > 100 m from a channel. Channel geometry does not appear to exert the significant influence on instream wood loads that has been documented for more laterally constrained channels. Channel-spanning jams are uncommon and appear to be transient features.