11N05-SO

A survey begins with aerial photography. Approximately 200,000 photographs to a scale of 1:15,000 are needed to cover the entire forest. The photographs are taken from an aircraft using a high-precision camera. Photo-interpreters then use special devices such as stereoscopes to examine the photographs individually. They identify areas that are fairly standard in terms of species composition, tree density and tree height. These areas or groupings are known as forest stands. Each stand is assigned an identification code. The contours from the aerial photographs are then drawn to a cartographical scale of 1:20,000 using a special software application. The resulting images are used to produce digital maps known as ecoforest maps. Because of the limited space available on the maps, the data are presented in code form.