The effects of forest management on erosion and soil productivity
Elliot, W.J.; Page-Dumroese, D.; Robichaud, P.R. 1999.
The effects of forest management on erosion and soil productivity.
Chapter 12 in
Lal, R., ed., Soil Quality and Soil Erosion.
Boca Raton, FL: CRC Press. 195-208.
Keywords: Soil Quality, Soil Erosion Prediction, WEPP
In forest conditions, surface runoff and soil erosion are generally low because
of the surface litter cover. Hydraulic conductivities are in excess of 15 mm/hr, and erosion
rates are generally less than 0.1 Mg/ha. If the litter layer is disturbed, then runoff and
erosion rates can increase by several magnitudes. Disturbances can be natural, such as wild
fire, or human-induced, such as harvesting or prescription-burning for ecosystem management,
where conductivities can drop to under 5 mm/hr, and erosion rates can exceed 20 Mg/ha. Roads
adversely impact forest soil productivity by directly reducing the productive area, and by
causing the greatest amount of soil erosion. Conductivities of roads have been measured to
be less than 1 mm/hr, and erosion can exceed 100 Mg/ha. Harvesting activities
reduce surface cover and compact the soil, leading to increased runoff and erosion.
Erosion generally decreases productivity of forests by decreasing the available soil
water for forest growth, and through loss of nutrients in eroded sediment. The Water
Erosion Prediction Project (WEPP) model is shown to be a useful tool in predicting the
erosion impacts of different levels of vegetation removal at harvest, and different levels
of compaction. WEPP predicted that the nutrients lost through the organic matter in
sediments are significant, but less than nutrient loss through tree removal. Work is
ongoing to collect long-term site productivity data from numerous sites to aid in the
analysis of forest management on soil erosion and site productivity.
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