Estimating regional forest cover in East Texas using Enhanced Thematic Mapper (ETM+) data

The USDA Forest Service, through its Forest Inventory and Analysis (FIA) program, periodically estimates forest/non-forest area at the county level using aerial photographs. Satellite-based remotely sensed data and digital image processing techniques could substantially reduce the time required to generate this information. Satellites collect data on a repeat basis and with higher frequency than the aerial photos that are currently used for this purpose. In addition to the forest cover estimates, the USDA could use satellite data to generate maps depicting the spatial distribution of forest cover. However, few studies have tested the utility of medium-resolution satellite data for FIA purposes. We tested the potential for using LANDSAT satellite data to obtain forest cover estimates for a six-county region in East Texas. Satellite data were processed using a combination of image classification techniques that could be repeated in other regions of the USA. Results were compared with the results of traditional photo-based estimation techniques and were comparable within a 95% confidence interval. Based on this study we recommend that medium-resolution satellite data can be used for obtaining county-level forest cover estimates.