Use of Aerial Photos for Timber Surveys in the Rocky Mountain Region

After three seasons of experimental work, covering 500,000 acres in the Rocky Mountain Region of the Forest Service a procedure using aerial photographs to secure very accurate and reliable timber type maps and volume estimates for timber sale and management plan purposes has been developed. This method of timber survey is especially adapted to regions where types are distinct and where mature timber, pole stands, reproduction, aspen, open parks, barren areas, etc., can, after some experience, be distinguished on the photographs by the survey crew. When these photographs are viewed under the stereoscope, topography stands out in detail, and location of streams, logging unit divides, and other important factors of topography which control logging can be determined accurately and can be shown on a map of the area. Before undertaking a large scale survey project using the aerial photo method, a planimetric map based on aerial survey should be available on which to transfer the information secured by the timber survey crews to form the final map.