NCRS - The Changing Midwest Assessment

Since the 1930s the Forest Inventory and Analysis (FIA) Research Unit of the Forest Service has monitored land use across the seven states of the North Central Region. In particular, FIA has gone to great lengths to measure the extent and condition of public and private forests. In recent years the Forest Service has also begun to monitor land cover.

Land cover is related to land use, but it has a broader meaning. For example, consider the difference between forest, which is a type of land use, and forestland, which is the corresponding land cover type. Forest is defined as a tract of land of at least 1 acre, at least 120 feet wide, and at least 16.7% stocked with forest trees of any size. In the process of measuring forests field survey crews record the amount (i.e., area, volume, and size-class) and condition of trees by species and Forest Type Group. Forestland is the land cover type that describes a tract of land upon which trees are the dominant feature; as a general rule, a tract of land must have a canopy closure of at least 25 percent in order to be classified as forestland. Forestland is measured remotely using aerial photography and satellite imagery.

In measuring land cover we focused on three cover types: Agriculture, Forestland, and Urban. Land cover was measured at a resolution of 1 km (see Bergen, Brown, Rutherford, and Gustafson, 2002).