Multi-source national forest inventory of Finland.

The National Forest Inventory of Finland has produced large-area forest resource information during 70 years. The Finnish Forest Research Institute started to develop a new inventory system 1989, during the eight rotation, in order to get geographicly localized, up-to-date information and for smaller areas than earlier. The method exploits satellite image data and digital map data in addition to the ground measurements. Image analysis method has been chosen in such a way that estimates of all variables of inventory could have been computed for each pixel. The system is now operative and the inventory has been made in an area of about 8 million hectares producing theme maps and statistics for large and small areas (even single stands). The results has been compared with the estimates of standwise forest inventory and in large areas with those based on field sample plots of the National forest inventory only. These results match quite well indicating the applicability of small area estimates.