Using classified Landsat Thematic Mapper data for stratification in a statewide forest inventory

The 1998 Indiana/Illinois forest inventory (USDA Forest Service, Forest Inventory and Analysis (FIA)) used Landsat Thematic Mapper (TM} data for stratification. Classified images made by the National Gap Analysis Program (GAP) stratified FIA plots into four classes (nonforest, nonforest/forest, forest/nonforest, and forest) based on a two pixel forest edge buffer zone. Estimates based on twophase sampling for stratification were made at the county level. This procedure differed from methods used in previous inventories where stratification was based on the stereoscopic examination of aerial photo plots. Changes in plot design, sampling intensity, and population parameters between 1986 and 1999 make it impossible to attribute differences in sampling errors entirely to this change in methods. The stratified sample estimates based on TM data provided good estimates and greatly reduced costs by eliminating the need for thousands of aerial photos and manual interpretation of several hundred thousand photo plots.