This zone extends from sea level to about 4,500 feet. This is what most people think of when you say Arizona. This zone is the lower desert, home of Saguaros and Chollas, Palo Verde and Mesquite Trees, Coyotes and Heat.
From about 4,500 feet to 6,500 feet, this zone includes scrub pine. You'll find juniper and pinion here, along with some small oaks.
From about 6,500 to 8,000 feet. This is the terrain found on the Mogollon Rim and near Flagstaff. It also includes Douglas Fur and Oak. The largest stand of Ponderosa Pine in the U.S. is found in this region, it extends east from Williams, AZ to the New Mexico border.
8,000 feet to 9,500 feet. This zone includes Aspen, Fir and Spruce. Usually damp and cool.
From 9,500 feet up to 11,500. You'll find fur, spruce and some pine here. Tree-line ends near the top. Guaranteed to be cold!
Above the timberline on the San Fransisco Peaks (11,500 feet to the top of Mount Humphreys at 12,643 feet). This is above the tree-line. You will find species of plants that grow nowhere else in the world however. Artic type of weather!