Map showing precipitation and characteristic vegetation zones for western Oregon forests. Gray dashed lines mark Cascade Range subprovince boundaries for Western Cascades and High Cascades, from figure 1. In Oregon, precipitation generally increases eastward into the Cascade Range, then diminishes abruptly east of the range crest. Vegetation zones after R. Frenkel and S Kolar as depicted in Atlas of Oregon (1st ed., 1970). A similar zone map published more recently as Ecoregions of Oregon by Thorson and others (2003). Precipitation base map, created July 10, 2012. used with permission from PRISM Climate Group, Oregon State University, Copyright © 2012, http://prism.oregonstate.edu.