The impact of intensive forest management on carbon stores in forest ecosystems

People are largely dependent on forests for their construction needs, fuel.food and fiber. An increasing demand for these products has naturally lead tointensive management practices that maximize net biomass harvested. Thisexpansion of intensive management of forest resources for timber production withthe human population growth may have a profound effect on the role forests playin the global carbon cycle. First, the transition from old-growth to intensivelymanaged second-growth forest with short rotations entails major long-termecosystem changes including the reduction of total woody biomass. Although thebiomass of living trees can be restored within a relatively short period of time. deadwood biomass takes considerably longer to reach pre-harvest levels; thereforecommonly used rotations are too short for the latter part of ecosystem to recoverfully. As dead trees amount for 14-18% of the total woody biomass stores in anatural forest, a considerable amount of carbon can be released if this material isnot replaced. Second, economically efficient, intensive forest management systemsthat include commercial thinning and wood salvage can further reduce the totalbiomass loading of second-growth forests. Long-term study of live and dead woodin thinning trials in the Pacific Northwest and in northwestern Russia suggest thatintensive practices can reduce total woody biomass averaged over rotation to10-25% that found in a natural old-growth forest. Therefore intensive forestmanagement practices may maximize the supply of raw materials, but they mayalso generate a major carbon flux into the atmosphere. This flux may be
significant despite the fact the land-use type (i.e.. forest) remains the same. Effect ofintensive forest management practices should be included in future carbon budgetsand in developing forest management strategies aimed at increasing carbon storagein forest ecosystems.