Kobayashi, Shigeo; Swanson, Frederick J. 1987. Effects of harvesting impacts on soil of a Douglas-fir forest in the Cascade Mountains, Oregon, U.S.A. In: Fujimori, Takao; Kimura, Makoto, eds. Human impacts and management of mountain forests: Proceedings of an international (IUFRO) workshop; 1987 September 5-13; Japan. Ibaraki, Japan: Forestry and Forest Products Research Institute: 31-45.
The effects of forest harvesting impacts on soilproperties were investigated at the old-grm:th Douglas-fir(Pseudotsuga menziesii) forest in the Cascade mountains. To
clarify the mechanisms of soil change, soil profiles i:ere
described and soil chemical and physical properties wereanalyzed at 5 cm depth. Landform units L•re classified
numerically. Direct impacts of forest harvest to the soilwere evaluated as compaction, tillage. and accumulationand/or mixing of organic matter Indirect impacts of harvestresulted in minerization of topsoil, decomposition of or-ganic matter, repellency revelation, and uresion. These
direct and indirect impacts caused changes soilproperties that 'cried along landform units. On the Terracelandform unit, the saturated hydraulic conductivity ratesdecreased notably and bulk density increased. The SeepageSlope unit exhibited increased hardness of B horizon anddecreased total porosity. Fine porosity increased andcoarse porosity decreased as a result of compaction. TheConvex Creepslope (I) experienced decreased exchangeablecations and saturated hydraulic conductivity by the repel-Midsiope (1) showed the highest contents of organic carbonand total nitrogen caused by mixing of organic matter. TheCoiluvial Footslope indicated to decrease the thickness of Aand B horizon and increase the exchangeable cations Ahorizon.