Measuring and modelling soil erosion processes in forests
Elliot, W.J.; Foltz, R.B.; Robichaud, P.R. 2000.
Measuring and modelling soil erosion processes in forests.
Landwards 55(2): 8-25.
Presented at the Forestry Engineering for Tomorrow Conference,
28 June 1999, Edinburgh, Scotland.
A prime forest resource is clean water for downstream beneficial uses.
Sediment from forests may impair those beneficial uses. Sedimentation by water erosion is rare unless
road activities, timber harvesting, or fire disturb the forest. We have been researching
forest soil erosion processes and developing erosion prediction models for more than 10 years.
This paper presents an overview of some of our findings.
Rut formation dominates road erosion processes. Road maintenance practices that reduce
rutting also reduce erosion rates. Road ditches can also be a major source of sediment if
the ditches are recently disturbed from construction or maintenance. Generally, if roads
are properly designed and located at a sufficient distance from nearby streams, then
stream sedimentation is minimal.
Forest harvesting activities can lead to increased erosion due to the exposure of mineral
soil or the alteration of soil properties due to compaction. Fires can lead to major erosion
in forests, especially during the first few years after the fire. Spatial variability of the
severity of disturbance is common after fire. Fire effects include a reduction in soil
hydraulic conductivity and a loss of the protective organic layer on the soil surface.
These two impacts can increase erosion rates by several magnitudes.
The Water Erosion Prediction Project (WEPP) model can model disturbed forest erosion
processes. WEPP can be a powerful tool to provide quantitative estimates of the amount
of sediment entering forest streams for many management activities. Templates for the
current WEPP model and user-friendly interfaces have been developed to assist field
managers to apply this technology to various forest conditions.
Moscow FSL publication no. 2000h