National forest inventory in the USA: An outline of the procedure

Abstract

Summary The US Forest Service manages 56 million hectares of forest but maintains an inventory of all US forests covering some 295 million hectares - approximately seven times the area of Australia's forests. Its national inventory program - the Forest Inventory and Analysis (FIA) program - commenced in 1930 and now systematically samples approximately 6.5 million photo-points, plus a subsample of 135 000 forested ground plots to obtain estimates of timber and non-timber resources at national, regional, state, and sub-state levels on a seven to 14 year cycle in contiguous USA. Grid sampling on air-photos provides data for stratifying cover types and estimating areas. Double sampling on permanent ground plots provides data to determine volumes, growth, mortality, regeneration, structure and other vegetation and habitat values. A related Forest Health Monitoring Program monitors status, changes, and long-term trends in the distributions and health of forest ecosystems. The paper outlines the objectives and methods of these inventories and considers their potential use of new technologies and their relevance to the National Forest Inventory of Australia.