Coastal Temperate Rainforest - Remaining Late Seral Forest Fragments in Northwest North America

This layer represents the remaining late seral forest fragments within the original distribution of the coastal temperate rain forest. Excerpt from "The Rain Forests of Home: An Atlas of People and Place. Part 1: Natural Forests and Native Languages of the Coastal Temperate Rainforest" (p. 13): Analysts determined the extent of the remaining undeveloped forest by subtracting a GIS layer representing areas primarily affected by human activity from the layer of original forest distribution. The "human development" layer was assembled from sources giving some indication of areas primarily affected by farming, logging, or urban development. These sources included forest and vegetation classification data sets as well as more general land use and land cover data sets. Similarly, contiguous areas of remaining mature forest were compiled in the GIS from a number of forest classification data sets for specific areas within the region, mainly at the state or provincial level. Analysts selected the data sets that offered the widest coverage for each given area, and those that best distinguished managed from unmanaged forest. Where necessary, auxiliary data sets were added to complete the geographic coverage. Again, analysts extracted from each data set just those areas indicating mature or old-growth forest (or some surrogate measure on this condition), on the assumption that these areas best represented undeveloped forests. Analysts recognized that some very old second growth might be included and areas of undeveloped forest may have been omitted. In Alaska, the non-forest undeveloped areas were taken from satelite imagery and GIS databases that distinguish forest from non-forest types. Remaining mature forest areas included those classified as forests but not shown in databases of harvested areas.