NLCD Land Cover Change Index (CONUS)
The NLCD change index summarizes NLCD land cover change into 11 change classes. These classes are intended to communicate thematic change impact in an easy to visualize format, and were based on the following hierarchy: water, developed, wetland (emergent herbaceous wetland, woody wetland), agriculture (cultivated crop, pasture hay), rangeland grass and shrub, and forest (with two additional forest regeneration classes). For example, pixels assigned to the agriculture change index included “from or to agriculture” but not “from or to water” (as these pixels were already assigned to the water index), and so on down the hierarchy. A pixel was assigned to a class regardless of when the change occurred or other land cover changes that occurred. Change classes are assigned according to the Anderson 1 (Anderson et al., 1976) level of the legend, with two exceptions: wetland within change, which quantifies change between emergent herbaceous wetland and woody wetland; and change between cultivated crop and pasture/hay. For NLCD 2021, land cover change between 2019 and 2021 was added to the published NLCD2019 change index raster, which included change between 2001, 2004, 2006, 2008, 2011, 2013, 2016, and 2019.