The influence of some forest operations on the sustainable management of forest soils -a review

Abstract

This review paper describes the nature and scale of changes to forest soils brought about by forestry operations. A relatively non-technical approach is adopted with the aim of stimulating debate within as wide an audience as possible. The paper does not aim to be exhaustive but rather a position statement. Areas where further study is required are highlighted. The concept of sustainability is explored in relation to forest soils, and the condition highlighted is that impacts of forest management operations should not, in the long term, exceed the capacity of soil to recover by natural processes (e.g. erosion losses should not exceed soil formation rates, nutrient removals should not exceed nutrient inputs etc.). Soil erosion, nutrient removal, compaction, and changes in organic matter content and soil water status are identified as the most important processes involved in the impacts of management. The impacts of some of the more intensive forest management regimes on soil compaction, nutrient removal and erosion rates appear to be of similar magnitude to the recovery capacity of soils. Where the most intensive forms of forest operation are used on susceptible sites some degree of long-term soil degradation appears to he likely, and it can be regarded as valid to describe such management practices as unsustainable. However, the scale of occurrence of such management is probably relatively modest, and decreasing. On less susceptible sites, and where less intensive forms of management are employed, impacts on soils are low enough for management to be regarded as sustainable, and are often less than under pre-existing land uses. Compaction caused by heavy harvesting and extraction machinery, nutrient depletion resulting from whole tree harvesting on infertile sites where rotations are short, and erosion following cultivation and harvesting on erodible soils are the greatest causes of concern. Compliance with recent Forestry Commission guidelines should lead to lower impacts than those recorded during recent decades. However, rotation-length audits of the impacts of different forest management regimes on a range of site types are needed before definitive statements about the sustainability of management operations can be made.