Sierra Ancha Experimental Forest

The USDA Forest Service first established research plots in Sierra Ancha in 1925. The research area was named the Parker Creek Experimental Forest in 1932, with a research focus on watershed management. This experimental forest was expanded and renamed the Sierra Ancha Experimental Forest in 1938.

The initial research mission on the newly formed experimental forest was to study the effects of grazed and ungrazed vegetation on water yields and to learn more about water cycle relationships with the varying vegetation zones of the Sierra Ancha. Research was conducted at Parker Creek, Natural Drainages, and Workman Creek.

Hydrologic records began after the Civilian Conservation Corps installed weirs and equipment in the 1930s. The Workman Creek watersheds (North Fork, Middle Fork and South Fork) are located at intermediate elevations (4,800 to 6,000 ft) and fall within the high-elevation mixed conifer vegetation type. The four Natural Drainages watersheds are located in the chaparral vegetation zone of the experimental forest and range from 9 to 19 acres in size, and hydrologic records began here in 1934.

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; 1,460 to 1,830 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 57 percent of the forest.

Research – Historical and Present

Experimental Watersheds

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. More information on Sierra Ancha watershed research is available here through the RMRS Air, Water, and Aquatic Environments Program.

The website Managing Arid and Semi-Arid Watersheds provides a plethora of information on experimental watersheds in Arizona, including historic flow data, GIS maps, and general description. The watersheds in the Sierra Ancha are just one of many of these experimental watersheds in Arizona.

Monitoring Effects of Air Pollution

The International Co-operative Program on Assessment and Monitoring of Air Pollution Effects on Forests (ICP) was launched in 1985 under the Convention on Long-range Transboundary Air Pollution of the United Nations Economic Commission for Europe due to the growing public awareness of possible adverse effects of air pollution on forests.

ICP monitors the forest condition in Europe, in cooperation with the European Union using two different monitoring intensity levels. The first grid (called Level I) is based on around 6000 observation plots on a systematic transnational grid of 16 x 16 km throughout Europe. The intensive monitoring level comprises around 800 Level II plots in selected forest ecosystems in Europe. Currently 41 countries participate in the ICP Forests.

In 2007, the U.S. Forest Service set up a synthesis network of 18 sites throughout the U.S., including the Sierra Ancha, with an ICP Level II platform at each site. Each site will include a NADP weather station, UV Radiation Monitors and Ozone Sensors. The Sierra Ancha EF was chosen to be part of this network because it is the most southern Experimental Forest in the contiguous US and because it is downwind from Phoenix, one of the nation's largest metropolitan areas.

For more information, see Monitoring the effects of air-quality on forests: An overview of the Sierra Ancha Experimental Forest ICP-Level II Site.

Developing pollinator-dependent plant materials for use in a growing restoration economy

Located on the Sierra Ancha Experimental Forest, this project uses a common garden approach to determine which plant species are best suited for supporting pollinator communities and are most appropriate for restoration activities. Findings from the study will be used to 1) improve pollinator habitat, 2) increase seed stocks of native flowering species for use in restoration, 3) inform U.S. seed zone guidelines and 4) help predict plant-pollinator response to climate change. This carries on a long tradition at the Sierra Ancha Experimental Forest of using common gardens in botanical research. As far back as the 1920s and 30s common gardens were used to study evapotranspiration rates of native herbaceous and shrub species as well as evaluate the potential use of certain species for erosion control. Some of these the same gardens are now being restored nearly a century later for use in this study.

100 years of vegetation change at the Sierra Ancha Experimental Forest

This project incorporates historical data collected at the Sierra Ancha Experimental Forest nearly 100 years ago to determine how plant communities have changed over that period of time.

Sierra Ancha Experimental Forest Vegetation Mapping Project

The Sierra Ancha Experimental Forest (SAEF) Vegetation Mapping Project uses unmanned aerial vehicles (UAVs) to create highly detailed vegetation maps using Structure From Motion technology.  These maps are then used to overlay historical vegetation maps made nearly 100 years ago to determine how vegetation has changed over the last century.

The long-term effects of high severity wildfire on snow accumulation, ablation and soil water content

Snowtography technology will be used in conjunction with soil moisture sensors to measure and correlate snow accumulation, ablation and soil water content with vegetation in a wildfire affected area of the Sierra Ancha Experimental Forest.

• Sierra Ancha climate data — Monthly and daily climate data from 2000-2011 for the Experimental Forest
• SNOTEL — The Natural Resources Conservation Service installs, operates, and maintains an extensive, automated system to collect snowpack and related climatic data in the Western United States, including up-to-date precipitation and snow data for Workman Creek.
• Parker Creek flow data from USGS — Up-to-date flow data from Parker Creek as it flows out of the Sierra Ancha Experimental Forest.
• Historical photographs — Historical photographs of research at Sierra Ancha Experimental Forest in Arizona, including research techniques, locations of sample plots, harvesting methods, climatological equipment, diseases, planting, and other factors impacting a forest. Repeat photo series contain information of environmental changes over time.
• Historical hydrology flow data
• Main Dam (1939-1980)
• South Fork (1939-1980)
• Middle Fork (1956-1979)
• North Fork (1977-1980)
• Managing Arid and Semi-Arid Watersheds — Historic flow data, GIS maps, and general descriptions of experimental watersheds in Arizona.