The TAMM/NAPAP/ATLAS/AREACHANGE (TNAA) system and the Forest and Agriculture Sector Optimization Model (FASOM) are two large-scale forestry sector modeling systems that have been employed to analyze the U.S. forest resource situation. The TNAA system of static, spatial equilibrium models has been applied to make 50-year projections of the U.S. forest sector for more than 20 years. Much of its input on forest management behavior and decisions about use of forestland derives from expert-based systems external to the TNAA system. FASOM, a spatial intertemporal optimization model, directly incorporates decisions on management investment and land use options relative to agricultural alternatives as endogenous model elements. The paper contrasts projections of private forest investment from the TNAA and FASOM models, focusing on the southern United States. Comparison of the TNAA base case and an investment-restricted scenario from FASOM, both of which reflect a continuation of recent behavioral tendencies by nonindustrial private owners, suggests that Southern private timberlands have considerable biological and economic potential for intensified forest management. Unrestricted FASOM projections confirm that added investment could lead to substantially larger timber harvest volumes and lower prices than those projected in the base/restricted cases. But even under the more intensive investment scenarios, naturally regenerated forests would cover three-quarters of the future private timberland base and hardwoods would continue to dominate the inventory structure.