Tom Nisbet

The role of forest management in controlling diffuse pollution in UK forestry

Abstract Forests and forest management practices have been identified as potentially important non-point sources of water pollution in upland areas of the United Kingdom. The major water quality concerns are recognised as being: increased turbidity and sedimentation due to the soil disturbance accompanying cultivation, drainage, road construction and harvesting operations; increased phosphate concentrations following aerial applications of fertiliser leading to eutrophication of standing waters; and the enhanced capture of acid deposition by forest canopies resulting in further acidification of surface waters. In order to address these concerns the UK Forestry Commission introduced their ‘Forests and Water Guidelines’ in 1988. The guidelines were prepared by a joint forest and water industry working group and provide advice on working methods and measures that should be taken to ensure that forests not only protect, but also enhance the freshwater environment. This paper reviews the evidence from recent studies in the UK designed to test the efficacy of the guidelines in practice. Results demonstrate that best management practices can be very effective in limiting soil erosion, and so preventing unacceptable increases in turbidity and sedimentation within watercourses. Technological improvements have allowed better targeting of aerial fertiliser applications and, when combined with protective measures such as riparian buffer strips, have helped to reduce the threat of nutrient enrichment. There has also been significant progress in tackling the acidification issue with the critical loads approach being used to identify those areas at risk from a forest acidification effect. Results to date from long-term studies provide support for this approach, although further testing is required. It is concluded that the ‘Forests and Water Guidelines’ appear to be effective in controlling the threat of diffuse pollution from forestry in the UK.