'Anti-erosion' logs across paths in the southern uKhahlamba-Drakensberg Transfrontier Park, South Africa: Cure or curse?

Although path erosion is a widely studied topic, little is known about the potential environmental impact of 'anti-erosion' logs that are placed across paths to divert water. Results are reported of a project that assesses the placement of logs across paths in the uKhahlamba-Drakensberg Transfrontier Park, South Africa. The log spacing and dimensions are compared and correlated with path dimensions. Paths and diversion furrows adjoining the logs are examined for their sedimentology, structural strength and moisture retention. Although no strong correlations exist between log dimensions and path characteristics, thicker logs are better able to reduce the rate at which sediment overflows the logs. Results indicate high shear strength and penetrometer values for the path tread; however drainage furrows which divert flow off the paths have low soil strength values. Anti-erosion loos are in some instances responsible for downslope path deepening, whilst upslope sedimentation along the path tread may lead to vegetation succession. Although such processes may lead to multiple path development, the logs have a positive role in ensuring that sediment is re-positioned across the slope, thus reducing potential soil loss. (C) 2007 Elsevier B.V. All rights reserved.