ANNOTATION: FIA BioSum is a concept-based methodology that generates cost estimates, identifies opportunities and evaluates the effectiveness of fuel treatments in region-wide forested landscapes. The BioSum modeling framework incorporates a transportation cost model, a treatment cost accounting module, a log valuation model, and a crown fire hazard evaluator with Forest Inventory and Analysis (FIA) plot data. ABSTRACT: FIA BioSum has been applied to a 25 million acre region of Oregon and California and to the entirety of Arizona and New Mexico in support of research studies and articles (e.g., Barbour et al. in review; Bilek et al. 2005), presentations to Washington Office, regional and forest staff, other scientists, forest and fire managers, and the biomass-to-energy community. Custom analyses have supported biomass plant capacity decisions (in Lakeview Oregon) and forest practices policy development (in California). The FIA BioSum simulation software, which provides users with a user-friendly, automated, integrated analysis environment and all the needed model components to conduct BioSum analyses for any area in the U.S. for which FIA plot and road network data are available, is in beta release and documentation, an on-line help subsystem, sample datasets, and a user tutorial are nearing completion. Results and Applications: Under a range of policy scenarios with different objectives in the Oregon and California regional analysis, removal of considerable amounts of commercial size trees is needed to accomplish fire hazard reduction goals when objectives are centered on either maximizing net revenue or maximizing treatment effectiveness. Even if the objective is to minimize merchantable volume about two thirds of the removed weight would be in sawlogs. Tops and limbs from merchantable commercial conifers and whole trees of hardwoods and non-commercial conifers are major sources of sub-merchantable wood for which there is essentially no market but bioenergy. Assuming a ten year implementation and depreciation of the biomass plants constructed to support fuel treatment, and treatment of all acres for which treatments would achieve fuel reduction benefits, the study region is capable of annually producing $590 million in net revenue, yielding 6 to 12 million green tons of biomass and 840 million to 1.2 billion cubic feet of merchantable wood, and over the course of a decade, achieving effective treatment of 2.8 to 8.1 million acres while providing bioenergy capacity of 496 to 1009 MW. Analysis with a range of forest bioenergy-facility capacities revealed robustness in the optimal spatial distribution of bioenergy facilities. This robustness depends on the extent of the transportation network relative to the sources of woody biomass and on the ability to change plot-treatment combinations to define different biomass collection areas. Custom analyses have been conducted in support of biomass plant capacity decisions (in Lakeview Oregon), forest practices policy development (by the California Dept. of Forestry and Fire in California), and regional analysis of opportunities to attract bioenergy investment capital (in New Mexico). DATA REQUIREMENTS: inventory plot data with expansion factors; road network with travel time per unit distance assigned to the road segments; silvicultural treatments coded in FVS; product prices. Also, a raft of assumptions, such as filters on what characteristics lead to an acre being a candidate for treatment, definitions of hazard, definitions of hazard improvement, choice of logging systems, objectives (make money, improve fuel hazard, maximize material removed, minimize material removed, etc.)