Jawbone Ridge

The area is rugged and remote, covering about 1442 acres (584 ha). Elevations range from 1250 ft (381 m) along the Tuolumne River to four summits atop Jawbone Ridge between 2841 and 3397 ft (866-1035 m). The south-facing slopes of the Tuolumne River Canyon vary from 30 to 110 percent.

Distinctive Features

Rare Plants: A list including 16 rare plant species believed to occur in the area is included. However, because no actual fieldwork was conducted in the study area and this list encompasses the entire lower elevation area of the Stanislaus National Forest, it is not accurate for the area

Rare Land Snails: Two candidates for Federal listing of endangered species (Monodenia circumcarinata and M. tuolumneana) endemic to the Tuolumne River Canyon may occur in the area.

Rare Birds: The bald eagle (Haliaaetus leucocephalus) and peregrine falcon (Falco peregrinus), which are considered by the Federal government to be endangered species, may occur in the area.

Jawbone Deer Herd: This study area and adjacent Jawbone Lava Flat are critical wintering ranges for mule deer (Odocoileus hemionus californicus).

Association Types

No sampling was conducted, and sizes of associations are not given.

Chamise Chaparral (37200, 37110): Typically, this association has 20-100 percent cover composed of Adenostoma fasciculatum with less than 20 percent of remaining vegetation composed of herbs, grasses, or other shrub species. In some areas Arctostaphylos manzanita, A. mewukka, Ceanothus cuneatus, C. diversifolius, and C. integerrimus may exceed 20 percent cover. Occasional emergent foothill pine (Pinus sabiniana) is also present. Other species include Lonicera sp., Chlorogalum pomeridianum, Eriodictyon californicum, Quercus chrysolepis, Castilleja spp., and Chamaebatia foliolosa. 

Chaparral covers the west third of the area on south- and west-facing slopes, forming a distinct border with the pine/oak vegetation type.

Grassland and Savanna (42200, 71140, 71310): This association is composed of 10-100 percent cover by grasses and herbs. Foothill pine, blue oak (Quercus douglasii), and California buckeye (Aesculus californica) comprise less than 10 percent cover. The most common herbs include Avena spp., Bromus spp., Elymus spp., Poa spp., Festuca spp., Aira caryophyllea, and several members of Polemoniaceae, Liliaceae, Scrophulariaceae, and Apiaceae. 

This association occurs in the west corner of the area throughout the entire elevational range of the area. Slopes are very steep with rock outcrops and talus throughout.

Oak Woodland (71140, 71410, 81320): This type occupies the smallest acreage of the area, occurring in upper draws and along the river. Dominant species include canyon live oak (Quercus chrysolepis), blue oak, and foothill pine. Species of lesser importance include Fraxinus dipetala, Umbellularia californica, and Cercocarpus betuloides. Oak species cover 20-100 percent of the community. This is probably the most species-rich community in the area.

Ponderosa Pine (Pinus ponderosa)/Oak Forest (71310, 71322): Editor’s note: Despite the name, ponderosa pine is not likely to occur here except rarely. The typical pine species is foothill pine. Aspect is largely east-southeast. From photos in the report, foothill pine appears to dominate the canopy; the subcanopy is dominated by oaks of varying density. These are primarily canyon live oak, interior live oak (Quercus wislizenii), and blue oak.

Plant Diversity

The plant list included in the ecological survey is adopted from a survey made in the Clavy-Wards Ferry Area, a much larger area than the study site. It is, thus, inaccurate for the specific study area.

Conflicting Impacts

Because of the inaccessible nature of the area, this ecological survey bears the distinction as being the only one not actually visited by the author. This inaccessibility as well as the steep slopes within the area greatly reduces the area’s usefulness as a research area; consequently, the candidate has been dropped from further consideration.