This dataset represents the probable original (prior to European settlement) distribution of the coastal temperate rain forest of western North America.
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. 11): Different methods were used throughout the range of coastal temperate rain forest to delineate probable original extent, depending on information availability. For British Columbia, the coastal western hemlock zone from the Ministry of Forest's biogeoclimatic zone classification was used to determine the temperate rain forest zone. The coast redwood zone was also mapped, based on a data layer of vegetation cover types of California. Outside British Columbia and California, areas having at least 1400 millimeters average annual precipitation were combined with areas having a mean annual temperature range of less than 22 degrees Celsius to distinguish temperate from wet boreal forests. The combined dataset, showing wet temperate areas, was then filtered with elevation data to exclude areas above 3,000 feet, which would be snow-dominated during winter. Areas of permanent snow and ice at the northern end of the range and non-forest areas (barren, shrub-dominated, and rock) were filtered out using generalized land cover data (based on the NDVI data set from the AVHRR satellite sensor). The resulting layer, combined with the coastal western hemlock biogeoclimatic zone for British Columbia and the redwood zone for California, represents the probable pre-European settlement distribution of coastal temperate rain forest.
