Study On The Impacts Of Forest Harvesting Methods On Physical And Chemical Properties Of Site Soils

AbstractBy using sites investigation and eXPeriment analyses, the dri-pacts of forest harvesting methods on the physical and chethecal prop-erties of forest soils are studied in the paper- The research results areshOwed as the fOllowtng:(1 ) FOrest cutting methods have few obvious dripacts on thephysical properties of site soils and remarkable whuences on chetheca1.properties of them' Alter cutting, the contents of the orgedc, nitro-gen, pH values and phosphorus are increased. The generation effectsof sites alter selective cutting are better than that after clear cutting.(2)Tractor skidding had remarkable impacts on the physical andchethecal properties of cutting sites. After tractor skidding, the soi11,are compressed and the contents of interspace are lessened- The nut-rition of soils lost seriously to have disadvantageous ialluences on the-generation and seediings growth. Anmal skidding has 1ower irnpactson site soils than tractor skidding.(3)The changes of physical properties of site soils have re1ationwith the times of tractor passing. The changes are remarkab1e whenthe times are 1 --5, whi1e the tdries are 6 -- 15, the changes are littleobvious and the times are over 16, the physical properties is notchanged. The changes of physical properties caused by whee1 tractorskidding are imre than track tractor skidding.(4)Winter operations have lower bopacts on site soi1s than sam-' The generation effects of tracks of winter operationsmer operations. rhe generation effects of tracks of winter operationsare better than that of summer operations.(5)Firing and piling cleallng methOds can cause the changes ofphysical properties of site soi1s and the changes are 1itt1e obvious.The ialluences of the two methcds on the chedrical properties are re-markable. After pi1ing cleallng, the contents of the orgdric and nut-. 1.rition of sites are higher than the reference places. The contents of kalium of firing sites are increased but the other nutrition lost more.According to the results, the reasonable cutting, skidding and clearing method are chosen to lessen the disadvantageous impacts of forest harvesting on site soils and to protect and improve the growth capacity of site soils.