Two higher elevation biotic communities find their west limits at the Peacock Mountains region. Upstream up Truxton Wash to the northeast, is a region of Plains and Great Basin Grassland along the Truxton Wash and mountain foothills; further east and northeast, on the west of the Coconino Plateau, (Hualapai Indian Reservation, and Aubrey Valley region), a large mostly continuous expanse of the grassland exists. The grassland is surrounded and intermixed with the 2nd higher elevation biotic community, Great Basin Conifer Woodland. Together, the woodland and the grassland encompass almost the entire north half of Arizona except for specific regions of desert (Painted Desert, the Great Basin Desertscrub, on the Colorado Plateau, or associated perimeter regions). Other exceptions are the highpoint communities of trees or alpine grasslands at the San Francisco Peaks region, or the Kaibab Plateau on the Grand Canyon North Rim, or a few other higher altitude locales. (The exceptions are the Subalpine Grassland, found especially in the White Mountains, or small areas at the San Francisco Peaks, and the Rocky Mountain Subalpine Conifer Forest found at both the White Mountains and San Francisco Peaks.)