Inventorying means the measuring or estimating the forest resources. In Finland, the most important inventorying process is the National Forest Inventory NFI (VMI in Finnish), a process that took earlier several years, during which the forest resources of the whole country are estimated. The first National Forest Inventory was carried out in the early 1920s.
Nowadays, the NFI is a continuous process. It comprises several aspects, such as estimating the number and growth of trees, forest health and variables linked with biodiversity. Other inventorying processes include various estimations of threatened species and their status. They also include estimating the number of threatened habitats.
The Inventorying is largely carried out with the help of laser scanning from an airplane. The three-dimensional data gives information on the structure of trees and terrain, for example.