National Forest Inventories

The National Forest Inventory is a system for monitoring Finnish forest resources, which regularly produces data on the quantity, growth and quality of trees, on types of land use and forest ownership, and on forest health and biodiversity. The inventories are based on long-term time series based on a uniform data collection, but also on the emergence of new needs and methods. They produce estimates on the number and growth of trees and other data, all of which serve as the basis for the national and regional forestry plans and programmes.

The first National Forest Inventory was conducted in the 1920s. The field measurements were completed in 1924, and the inventory results were published in 1927. In later years the inventorying has become continuous activity, producing time series which are unique even in world-wide comparisons. As a rule, an inventory of all Finnish forests from the south to the farthest north takes about ten years to complete. The inventories are carried out by the Finnish Forest Research Institute.

Most of the data generated in the inventory is based on field measurements. Other methods include the use of satellite images and other up-to-date data on forest resources and forest health and biodiversity.

The field measurements of the ninth National Forest Inventory were started in the summer of 1996 and the inventory was completed in 2003. During the inventory more than 80,000 sample plots were monitored, 66,000 of them on forestry land. In the sample plots, over 150 variables were estimated or measured. The computations concerned 520,000 trees, of which 74,000 were so-called sample trees, measured in more detail. The highest amount of monitoring groups in field work simultaneously was 13.

The ninth inventory was the first one to assess also biodiversity, for example, the amount of key biotopes and dead or decaying wood. In addition to field inventory data also satellite images and other kind of numeric sources were used. By satellite images it was possible to generalize the information gathered from sample areas.

More information on the results of the National Forest Inventories is published annually in the Statistical Yearbook of Forestry by the Finnish Forest Research Institute.

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