Alternative projections of the impacts of private investment on southern forests: A comparison of two large-scale forest sector models of the United States.

The TAMM/NAPAP/ATLAS/AREACHANGE (TNAA) system and the Forest and Agricultur e Sector Optimization Model (FASOM) are two large-scale forestry sector mod eling systems that have been employed to analyze the U.S. forest resource s ituation. The TNAA system of static, spatial equilibrium models has been ap plied to make 50-year projections of the U.S. forest sector for more than 2 0 years. Much of its input on forest management behavior and decisions abou t use of forestland derives from expert-based systems external to the TNAA system. FASOM, a spatial intertemporal optimization model, directly incorpo rates decisions on management investment and land use options relative to a gricultural alternatives as endogenous model elements. The paper contrasts projections of private forest investment from the TNAA and FASOM models, fo cusing on the southern United States. Comparison of the TNAA base case and an investment-restricted scenario from FASOM, both of which reflect a conti nuation of recent behavioral tendencies by nonindustrial private owners, su ggests that Southern private timberlands have considerable biological and e conomic potential for intensified forest management. Unrestricted FASOM pro jections confirm that added investment could lead to substantially larger t imber harvest volumes and lower prices than those projected in the base/res tricted cases. But even under the more intensive investment scenarios, natu rally regenerated forests would cover three-quarters of the future private timberland base and hardwoods would continue to dominate the inventory stru cture.