PNNL

Abstract

Various studies have found that forest management plays a critical role in understanding the carbon cycle in the integrated human-Earth system. This makes effectively representing forest management decisions such as planting and harvesting important. Here, we implement a novel dynamic forest harvest model in a global state of the art multi-sector dynamics model, namely the Global Change Analysis Model (GCAM). We implement an approach that explicitly tracks forest age and generates rotation ages for forest harvest that are responsive to changes in wood prices. Furthermore, the forest sector in GCAM competes for investment with other land use types in the future years based on harvest profit. Our baseline scenario results indicate that with the new forest harvest model, the current global wood product demand in GCAM can be met with minimal loss of old growth forest through the age -based harvest decisions. We find that economic pressure for deforestation and consequent loss of forest carbon is a bigger threat relative to harvests, especially in regions where food demand is expected to rise. Under alternative scenarios where an economic value is placed on carbon across the system, while there is an increase in forest plantations, there can be corresponding increases in roundwood prices in some regions as forest land competes with land for bio-energy crops. With these price increases, under these scenarios with carbon valued, the average rotation age globally can be 16 years higher than the business as usual. Thus, we find that multisectoral pressures can significantly affect trends in the forest sector under alternative scenarios.