Post-fire forestry management and nutrient losses in eucalyptus and pine plantations, northern Portugal

The impact of different logging techniques on nutrient losses in burnt euca lyptus and pine forests in northern Portugal was investigated. A variety of logging techniques is used in the region resulting in varying amounts of s lash debris on the slopes. The efficacy of this litter in reducing soil ero sion is well established but less is known about the impact on nutrient los ses. Small bounded plots were used to examine the impact of varying amounts of slash debris and pine-needle cover on nutrient losses in overland flow and adsorbed to eroded sediment over 19 months during the first two-three y ears after fire. Nutrient losses in solution and adsorbed to eroded sedimen t were substantially higher on burnt terrain due to increased erosion and o verland flow generation and high nutrient concentrations at the soil surfac e in the burned forests. Post-fire logging techniques in eucalyptus forests resulting in large amounts of litter debris on the slopes are effective at reducing eroded sediment nutrient losses but less effective at reducing lo sses in solution. In pine forests, litter is largely ineffective in reducin g solute and sediment nutrient losses. However, a covering of pine needles was shown to be highly effective in reducing eroded sediment nutrient losse s and to a lesser extent solute losses. Conservational methods of logging a re suggested for both eucalyptus and pine forests in the region. In the abs ence of such measures, the sustainability of short-rotation eucalyptus fore stry is questioned in northern Portugal. Copyright (C) 2000 John Wiley & So ns, Ltd.