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).

AR5 is a national, seamless land resource database. The dataset describes land resources (mainly land cover and productivity) based on a standardized national classification system with 104 classes. Special attention is given to the suitability of land for agricultural and forest production. Substantial areas of Norway are above the tree line. These areas are only mapped as “not classified” in AR5. Areas above the tree line have been mapped in AR50.

Features in AR5 are continuous areas with the same attributes assigned according to the classification criteria of AR5 with a geometric representation as polygons. The minimum mapping unit in AR5 is 0.05 hectare (500 m2) for agricultural areas, transport networks and water bodies. Furthermore 0.2 hectare (2000 m2) is the minimum mapping unit for forest, peat bogs and open areas. For urban areas the minimum mapping unit is 0.5 hectare and 2.5 hectare for perpetual snow and glaciers. The geometric accuracy for well-defined boundaries is 2 m or better. The point density is normally between 5 and 50 m.

AR5 is continually updated by municipal administrations and priority is given to agricultural- and urban areas. This is an integrated part of the maintenance of the municipal geospatial database. A centralized control and editing program is carried out by NFLI with a five year turnover period.

The primary attribute in the classification is Land type (ARTYPE). Note that agricultural land is subdivided in three classes at this level. Secondary attributes are tree type (ARTRESLAG), forest site class (ARSKOGBON) and soil type condition (ARGRUNNF). The WMS offers classification based on combinations of values from several attributes. A classification often used displays different classes of forest productivity and different types of agricultural land (fully cultivated, surface cultivated and pasture) simultaneously.

Neighboring AR5-features may have completely identical sets of attribute values. This may be due to practical issues, like avoiding extremely large features. In such cases, the AR5-border is represented as a fictitious AR5-border (a special feature type).