The Finnish National Forest Inventory

Abstract

The National Forest Inventory (NFI) of Finland has produced large-area forest resource infor- mation since the beginning of 1920s (Ilvessalo 1927). When the 10 th inventory (NFI10) started in 2004, the design was changed and the rotation shortened to 5 years. Measurements are done in the entire country each year through measuring one-fifth of the plots. About one-fifth of all plots are measured as perma- nent. Using field data only, it is possible to compute reliable estimates for large areas, the minimum size of the area is typically some hundreds of thousands of hectares. In practical forestry, estimates are also often required for smaller units such as municipalities with typical areas of tens of thousands of hectares. This is possible only if ancillary data are used in addition to sparse field data. The Finnish multisource NFI uses satellite images and digital map data, in addition to field data, and produces estimates for small areas and wall-to-wall maps. Information from the Finnish NFI has traditionally been used in large area forest management planning, such as planning regional and national level cutting, improving silviculture and forest regimes, making decisions concerning forest industry investments, and providing a basis for forest income taxation. The NFI also provides forest resource information for national and international forest statistics and processes such as the United Nations Food and Agriculture Organization's (FAO) Forest Resource Assessment process and the Land Use, Land-Use Change and Forestry reporting of the United Nations Framework Convention on Climate Change.. Sampling designs for the ninth inventory rotation (NFI9)—conducted from 1996 to 2003—and NFI10 are described, as well as the basic principles of estimation methods based on field data only.