ErrataThis errata is to correct error made on page 16, fourth paragraph down. Paragraph should read as follows:Stumpage demand and product recovery and conversion-Given the constrained form of the production functions in equation (11), the derived demand for stumpage is simply (apply Hotelling's lemma to equation (15) The 1993 timber assessment market model (TAMM) is a spatial model of the solidwood and timber inventory elements of the U.S. forest products sector. The TAMM model provides annual projections of volumes and prices in the solidwood products and sawtimber stumpage markets and estimates of total timber harvest and inventory by geographic region for periods of up to 50 years. TAMM and its companion models that project pulpwood and fuelwood use were developed to support the quinquennial Resource Planning Act (RPA) timber assessments and assessment updates conducted by the USDA Forest Service. This report summarizes the methods used to develop the various components of TAMM and the estimates of key behavioral parameters used in the TAMM structure, and also illustrates the use of TAMM with a base and several scenario projections.

Adams, Darius M.; Alig, Ralph J.; Callaway, J.M.; McCarl, Bruce A.; Winnett, Steven M. 1996. The forest and agricultural sector optimization model (FASOM): model structure and policy applications. Res. Pap. PNW-RP-495. Portland, OR: U.S. Department of Agriculture, Pacific Northwest Research Station. 60 p.The Forest and Agricultural Sector Optimization Model (FASOM) is a dynamic, nonlinear programming model of the forest and agricultural sectors in the United States. The FASOM model initially was developed to evaluate welfare and market impacts of alternative policies for sequestering carbon in trees but also has been applied to a wider range of forest and agricultural sector policy scenarios. We describe the model structure and give selected examples of policy applications. A summary of the data sources, input data file format, and the methods used to develop the input data files also are provided.The GAMS programming language is used for the compact representation of the large forestry and agricultural sectors and to solve the model; it was formulated originally as a nonlinear mathematical programming problem. The programming structure allows easy expansion of the FASOM model. FASOM can model the forest and agricultural sectors either independently or simultaneously. The modeling system is designed to provide information about the effects of a wide range of potential policies on carbon sequestration, market prices, land allocation, and consumer and producer welfare under alternative supply and demand scenarios and producer eligibility-participation constraints. The modeling system is designed so that the sensitivities of these policies and their results can be evaluated given different assumptions about policy structure and finances.25 References 31Appendix A: Scope of the ASM Version in FASOM

Two perennial problems in the management of uneven-aged forests are considered: (i) determination of the optimal sustainable distribution of trees by diameter class, i.e. stand structure, for a given initial stocking level, and (ii) the optimal cutting schedule for the conversion of an irregular stand to a target structure. It is shown, using examples for northern hardwood stands in Wisconsin, that both problems can be solved via mathematical programming techniques. The programming approaches utilize a set of nonlinear equation models for stand table projections which consider the interdependence of size classes within the stand. To illustrate procedures, optimal stand structures are found for a case where initial stand basal area is constrained to specified levels and the objective is to maximize value growth over the cutting cycle. A conversion cutting schedule is then determined for a case in which the objective is maximization of present worth. It is emphasized that both the optimal distribution and conversion problems can be generalized to consider a broad range of objective functions, lengths of cutting cycle, and constraints on the growing stock.

No abstract