International forest statistics such as those provided by the UN/ECEFAO Temperate and Boreal Forest Resource Assessment (TBFRA) are typically compiled from national surveys. However, the national systems of nomenclature as well as the definition of the attributes ofien vary considerably. The European Commission, DG VI, initiated a study to investigate the potential of a European Communication and Information System (EFICS). In the framework of the EFICS study, the effect of different definitions of forest key attributes was investigated. The main locus was on the forest area and growing stock attributes.

The study presented here shows the effect of different forest area definitions, applied to artificially generated forest pattern types, which are typical for southern, central, and northern European forests. In a sinmlation study, forest area was estimated according to crown coverage, width, and area criteria, applied in the 19 European countries. Forest area differed by up to 13 percent. The effect of different forest area definitions is highly correlated with the amount of area covered by open forest types. Moreover, different roles to delimit the potential forest area from non-forest land have been proven to be very decisive for forest area estimates.