United States of America (USA)

Abstract

Forest land in the United States of America (USA) currently exceeds 310 million ha, has generally been increasing since the 1920s, and represents more than 30% of the country. More than 200 million ha of forest land are similar to what is known elsewhere as productive forest land; 70% of this productive forest land is privately owned. The current form of the National Forest Inventory (NFI) was initiated in the early 1990s and is consistent across the entire country with respect to major features such as plot configuration, sampling design, core variables, measurement protocols, and reporting requirements. The Forest Vegetation Simulator (FVS) is the most widely used forest resource projection system, particularly by federal and state government agencies. FVS is an empirical, distance-independent, individual-tree forest growth modeling system that is constructed, maintained and updated by the U.S. Forest Service. The system is initiated with stand-level information and tree lists that can be obtained from the inventory database. The large-tree diameter increment and mortality models are the most important components and drive much of the system. Extensions in the form of integrated modules or independent programs have been developed for a variety of specialized applications including fire and fuels, insects and pathogens, climate change, and carbon accounting. The availability of NFI data in FVS-ready format has increased the utility of FVS for applications such as projections on National Forest lands, assessment of management alternatives and timber harvest methods, and large-scale forest health assessments. Application possibilities have been further enhanced via linkages between FVS and other software systems, databases, and geographic information systems.