The national land resource database (AR) classifies the land cover of mainland Norway according to its suitability for agriculture and natural plant production. National land resource datasets are available at scale 1:5.000 (AR5), 1:50.000 (AR50) and 1:250.000 (AR250). AR50 is the Norwegian medium resolution land resource dataset which covers the whole of mainland Norway. It is build and maintained for cartographic representations at regional level (1:100.000 to 1:300.000). The dataset is not intended for spatial analysis. Features in AR50 are continuous areas representated as polygons with attributes assigned according to the AR50 classification criteria. The primary level of classification is land type (arealtype) based on a combination of land cover and land useSecond level attributes are forest site quality class (skogbonitet) and forest cover type (treslag). Areas above the tree line, mountains and other open areas have been classified according to richness of the vegetation. AR50 contain also includes information about arable land when the land cover is bare land, marsh or forest. In AR50, the general minimum mapping unit is 1.5 hectares for polygons that have identical combinations of attribute values. Smaller mapping units occur between identical land types if they have different forest cover or forest site quality.
The dataset is a generalization of AR5 - the national land resource map at scale 1:5.000 - which covers all areas below the tree line (productive areas for agriculture and forestry). Above the tree line AR50 has been derived from satellite imagery (landsat-7, spot-4, IRS-1C) dating from 2005-2010. In areas with no feasible satellite imagery at the time the dataset was established, national topographic maps at scale 1:50.000 from the same period were used. The dataset is updated using generalized data from AR5 every 3 years. The current version is based on AR5 data available at the end of 2016. Satellite imagery and topographic maps are not updated.