THE INFLUENCE OF SOME FOREST OPERATIONS ON THE SUSTAINABLE MANAGEMENTOF FOREST SOILS - A REVIEW

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 capaci ty 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 identifie d as the most important processes involved in the impacts of managemen t. The impacts of some of the more intensive forest management regimes on soil compaction, nutrient removal and erosion rates appear to be o f 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 be likely, and it can be regarded as valid to describe such management practices as unsusta inable. However, the scale of occurrence of such management is probabl y relatively modest, and decreasing. On less susceptible sites, and wh ere less intensive forms of management are employed, impacts on soils are low enough for management to be regarded as sustainable, and are o ften less than under pre-existing land uses. Compaction caused by heav y harvesting and extraction machinery, nutrient depletion resulting fr om whole tree harvesting on infertile sites where rotations are short, and erosion following cultivation and harvesting on erodible soils ar e the greatest causes of concern. Compliance with recent Forestry Comm ission guidelines should lead to lower impacts than those recorded dur ing recent decades. However, rotation-length audits of the impacts of different forest management regimes on a range of site types are neede d before definitive statements about the sustainability of management operations can be made.