The U.S. Forest Service established the Sierra Ancha Experimental Forest in 1932 as a research area for studying watershed management. Located within the Tonto National Forest, the climate, soil, and landforms of the Sierra Ancha are representative of much of the southwestern region of the United States.
The Sierra Ancha Experimental Forest lies roughly 30 miles (48 km) northeast of Globe, Arizona. The Forest Service established Sierra Ancha in 1932 as a research area devoted to studying watershed management. Sierra Ancha lies along the crest of the Sierra Ancha Mountain range and includes areas between 3,550 to 7,723 feet (1082 to 2354 m) in elevation. Its 13,255 acres (5364 ha) are located within the Tonto National Forest. Climate, soil, and landforms are typical of much of the southwestern region, particularly Arizona, and are representative of the Verde, Salt, and Upper Gila watersheds. Plant types within the forest range from semi-desert shrub and grassland to pine-fir forests at higher elevations.
Research studies on watershed management problems in woodlands, chaparral, ponderosa pine, and pine-fir forests were conducted on the sites that ranged in size from several square meters to complete watersheds comprising several thousand hectares. The Sierra Ancha is still maintained as a research site under the administration of the Rocky Mountain Research Station. Many of the earlier watershed studies have been concluded and the results published. Currently, only one stream gauge is maintained for collecting long-term hydrologic data.
Precipitation averages about 33 inches (850 mm) at the higher elevations at Workman's Creek, 25 inches (635 mm) at the intermediate elevations (4,790 to 6,004 feet; 1460 to 1830 m) surrounding the headquarters, and 16 inches (410 mm) at the lower elevations. Geology of the range is complex, with sedimentary, metamorphic, and igneous rocks uplifted in a dome-like structure. Thick formations of Dripping Springs quartzite—dissected by deep canyons or with intrusions of diabase, basalt plugs, and sills—are common in much of the forest. Troy sandstone occurs at higher elevations. Researchers have identified eight plant types on the Sierra Ancha, listed in order of the elevation at which they are found (high to low): mixed conifer, mountain park, ponderosa pine, chaparral, oak woodland, desert grassland, desert shrub, and riparian. Chaparral shrubs cover fifty-seven percent of the forest.
Rocky Mountain Research Station maintains all of the buildings at the headquarters site.