02155naa a2200241 a 450000100080000000500110000800800410001910000190006024501130007926000090019252015100020165000110171165000210172265000170174365000130176065300230177365300110179665300110180765300120181865300220183070000190185277300420187117933362017-03-30       1997    bl ---       0--  u    #d1 aPENNOCK, D. J.  aClear-cut forest harvest impacts on soil quality indicators in the mixedwood forest of Saskatchewan, Canada.  c1997  aThe concept of soil quality is relevant to a range of human-indiced disturbances on soil; our objective was to examine the impact of clear-cutting on soil quality conditions in six Mixedwood (Populus tremuloides-Picea glauca) stands in Central Saskatchewan, Canada. Soil quality conditions at two short-term (1 to 5 years) and four medium-term (6 to 20 years) clear-cut sites were compared to eight mature Mixedwood sites. All sites had similar, albeit complex, distribution of soil and parent sediments. No major differences were observed between the short-term clear-cut sites and the mature Mixedwood sites. At the medium-term sites, substantial losses of soil organic carbon (24%), soil nitrogen (27%) and LFH thickness (28%) were observed, along with decreases in the soil surface (0 to 15 cm layer) of exchangeable calcium and magnesium (30%), soluble organic P (15%) and cation exchange capacity and base saturation (20%). The losses were much lower in the 15 to 45 cm layer of the soil. Overall, the levels of these soil components observed at the clear-cut sites were within the natural or undisturbed range as assessed at the mature Mixedwood sites; however the amounts of soil organic carbon and nitrogen at the clear-cut sites were lower than the natural range. Althhought the absolute levels of loss of soil organic carbon and nitrogen were much lower than in typical agricultural landscapes, the long-term ecological significance of the losses in these forested landscapes remains a concern.  aCanada  asoil degradation  asoil quality  aFloresta  aDegradacao do solo  aForest  aImpact  aImpacto  aQualidade do solo1 aKESSEL, C. van  tGeodermagv.75, n.1/2, p.13-32, 1997.