Stanislaus-Tuolumne Experimental Forest

Climate

Photo Credit

U.S. Forest Service/Tom Iraci

Tuolumne tract of the Stanislaus-Tuolumne Experimental forest in the foreground, with Pinecrest Lake in the background.

The climate is characterized by warm dry summers and cold wet winters. Annual precipitation averages 940 mm, more than half falling as snow between December 1 and March 31. In exceptional winters, snow may accumulate to depths over 3 m. Some drifts persist until mid-May. Little precipitation falls from June through September. Air temperatures during the year usually range from -23 to 35 °C. Average monthly minimum and maximum air temperatures range from -7 to 7 °C for January to 6 to 27 °C for July. The growing season lasts about 112 days.

Soils

Moderately deep, sandy to fine sandy loam soils of the Holland series are widespread. Soils are residual, derived from granite or diorite. Shallow soils from lava caps are found on some higher slopes and ridges, but overall site quality is high.

Vegetation

Sierra Nevada mixed conifer (SAF 243) covers 629 ha, though it can be considered a variant because Douglas-fir is largely absent and Jeffrey pine is present. The red fir forest cover type (SAF 207) covers 61 ha.

The Stanislaus-Tuolumne's two tracts are located 51 km east of Sonora, Tuolumne County. The forest can be reached via State Route 108, an all-weather road. The road network within the forest is unpaved except for Old Strawberry Road and Crabtree Road. Only the Old Strawberry Road and the small section of State Route 108 that crosses a corner of the Stanislaus tract are maintained during the winter. There are no facilities maintained by PSW as all buildings were transferred to the Summit Ranger District in the mid-1960s.

Maps

Lat. 38°10.4´ N, long. 120°0.0´ W

Google Map

Stanislaus-Tuolumne Experimental Forest Google Map

Topographic Map

Topographic map with outlines indicating the span of the Stanislaus-Tuolumne Experimental Forest

Research, Past and Present

Early research focused on the development of harvesting methods for (old-growth stands) that would provide for regeneration of sugar pine, Jeffrey pine, and ponderosa pine. Cone and seed production of pine and fir trees were monitored for 28 years. These data were used in the definitive work on seed and cone production. Later, the "unit area control" procedure was tested at the forest. "Site factor" stations were established in the early 1930s to monitor conditions related to seedling establishment. Studies of dwarf mistletoe were conducted here in the 1960s.

In 2006 research activity on the Experimental Forest again increased with the discovery of data associated with several historic “Methods of Cutting” plots. In 1929, all trees had been mapped and understory vegetation was quantified in three approximately 4 ha plots. The plots were then logged using different methods. Leave trees were individually tagged   many of these tags remain today. All trees were remapped in 2007 and 2008, making the plots among the oldest in the USFS system. A “variable density thinning” study, comparing thinning to a variable spatial structure (with tree groups and gaps, similar to the historic stand structure), thinning to an even crown spacing, and an un-thinned control, all with or without prescribed fire, was initiated on 240 acres in 2009. Another study comparing different thinning and prescribed fire treatments for alleviating mortality of large pines was installed on 135 acres in 2009.

Research Opportunities

The Stainslaus-Tuolumne is the site of studies related to mixed conifer stands, though on a small scale, because the area is limited. The stands here are remarkable because of the component of large sugar pine trees found throughout much of the forest.

Climatological measurements on the Stanislaus-Tuolumne include air and soil temperatures, relative humidity, barometric pressure, wind velocity, cloudiness, precipitation and soil moisture. Beginning in 1932 and 1933, records were kept for 30 years at one site, 19 years at another, and 11 years at three other sites. Trees in the Tuolumne Tract have been inventoried by stand condition classes within 1-ha divisions. The Stanislaus National Forest has mapped the soils to the family level. This soil survey supersedes a more detailed survey conducted by the University of California-Berkeley in 1942.

Historical Weather Data

Western Regional Climate Center - Pinecrest 2 RAWS

Publication

Stark, N. 1963. Thirty-year summary of climatological measurements from the central Sierra Nevada. Res. Note PSW-36. Berkeley, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Forest and Range Experiment Station. 15 p. (See Resources Documents.)