Increased erosion hazard resulting from log-row construction during conversion to plantation forest

• Published in: Forest ecology and management 1999-11, Vol.123 (2), p.145-155
• Main Authors: Prosser, Ian P, Abernethy, Bruce
• Format: Article
• Language: English
• Subjects: altitude; Digital elevation model; erosion control; Erosion hazard; Forest clearing; forest management; forest plantations; Gully erosion; land clearance; land use; logging; Pine plantation; sloping land; soil erosion; valleys; water erosion; water flow
• ISSN: 0378-1127; 1872-7042
• DOI: 10.1016/S0378-1127(99)00021-3

During forest clearing operations, embankments of logs are often constructed approximately parallel to contours. These log-rows resemble contour banks used in agriculture and it is expected that they perform a similar function of erosion control. Gully erosion was observed in a forest cleared for pine plantation in SE Australia. The gullies appeared to be associated with flow diversion around log-rows, particularly where log-rows do not follow the contour precisely. A digital elevation model (DEM) of the plantation was used to investigate how the distribution of erosion hazard, as a function of upslope contributing area and local gradient, had been changed by the log-rows. We found that benefits gained by decreased erosion hazard on many parts of the landscape were outweighed by increased erosion hazard at the end of log-rows and in hillslope valleys. This is because of the non-linear increase in erosion hazard with increasing upslope catchment area. The log-rows increased the probable extent of gully erosion by 1.5–1.7 times and the total sediment transport capacity, summed over the landscape, by 1.5 times. The results lead us to suggest techniques for improved log-row construction and plantation preparation.