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Sierra Ancha Experimental Forest

The Sierra Ancha Experimental Forest, located on the Tonto National Forest about 48 km northeast of Globe, Arizona, was established in 1932 as a research area devoted to studying watershed management. This 5,364- ha experimental area is typical of watershed and vegetation conditions throughout the Southwest, particularly in Arizona.

The climate, soil, and physiography are typical of much of the southwestern region, and are particularly representative of the Verde, Salt, and Upper Gila watersheds. The Sierra Ancha lies along the crest of the Sierra Ancha Mountain range and includes areas between 1,082 to 2,354 m in elevation. Vegetation types within the forest range from semidesert shrub and grassland to the pine-fir forests at higher elevations.


Precipitation averages about 850 mm at the higher elevations at Workman's Creek, 635 mm at the intermediate elevations (1,460 to 1,830 m) surrounding the headquarters, and 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 and basalt plugs and sills are common in much of the forest. Troy sandstone occurs at higher elevations.


Eight vegetation types have been identified on the Sierra Ancha including, from the high elevations to low: mixed conifer, mountain park, ponderosa pine, chaparral, oak woodland, desert grassland, desert shrub, and riparian. Fifty-seven percent of the forest is covered by chaparral shrubs.

Research, Past and Present

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.


Collaborators have included the Salt River Water Users Association, Tonto National Forest, Arizona State University, and University of Arizona.


All of the buildings at the headquarters site are being maintained by the Rocky Mountain Research Station.

Lat. 33.5 N, long. 111 W

Contact Information

Sierra Ancha Experimental Forest
US Forest Service

Rocky Mountain Research Station
2500 South Pine Knoll
Flagstaff, Arizona 86001-6381
Tel: (928) 556-2176