CARBON BALANCES OF LAND USE AND BIOENERGY OPTIONS

Abstract

Forestry and bioenergy strategies offer the prospect of reduced CO 2 emissions to the atmosphere. Such strategies can affect the net flux of C to the atmosphere through 4 mechanisms: storage of C in the biosphere, storage of C in forest products, use of biofuels to displace fossil-fuels, and reduction of fossile fuel use because wood products often displace other products which require more fossil fuel for their production. A mathematical model was used to examine these mechanisms for 16 land-use and bioenergy scenarios. Over long time intervals the amount of C stored in the biosphere and in forest products reaches a steady state and continuing mitigation of C emissions depends on the extent to which fossil-fuels are displaced by biofuels and wood products. The relative effectiveness of alternative forest and bioenergy strategies and their impact on net C emissions strongly depend, for example, on the productivity of the site, its current usage, and the efficiency with which the harvest is used. When growth rates are high and harvest is used efficiently, the dominant opportunity for net reduction in C emissions is seen to be fossil-fuel displacement. The net C balance at the end of 100 years for the scenario where trees are harvested and used for energy and traditional forest products is very similar to the scenario, where reforestation and forest protection strategies are implemented.