Santa Rosa and San Jacinto Mountains National Monument - Landscape, Vegetation and Wildlife

Landscape, Vegetation and Wildlife

The monument is oriented northwest to southeast along the edge of the broad Coachella Valley, and the terrain rises sharply from below sea level to nearly 11,000 feet (3,400 m). These mountains are a part of the Peninsular Range Province, which extends from the Baja Peninsula in Mexico to San Jacinto Mountains in California. San Jacinto Peak is the highest point in the Peninsular Range Province and has one of the steepest fault-block escarpments in North America.

The differences in elevation, temperature, and moisture gives rise to diverse vegetation. Being the western boundary of the Sonoran Desert, the eastern mountainslopes are hotter and drier, while the western side is affected by the Pacific Ocean and receives more precipitation with cooler temperatures. There are several major vegetation areas ranging from sand dunes/sand fields, chaparral and mesquite to riparian zones of willow and cottonwood, desert fan palm oasis woodland, and pinyon pine woodland, with the highest elevations supporting lodgepole pine timberline forest.

Another factor influencing plant and animal species is the "island" aspect of the San Jacinto Mountains and the Peninsular Range, the unique isolation of the landform on three sides-the Pacific Ocean to the west, the Salton Trough/desert environment in the east, and to the north, the San Gorgonio Pass. Biologists believe that this isolation has contributed to evolution of subspecies such as the San Diego mountain kingsnake.

The California fan palm (Washingtonia filifera) groves, part of the natural community of oasis riparian woodland, are located at permanent water sites of both Santa Rosa and San Jacinto Mountains. The fan palm is a relict species, although not listed under the Endangered Species Act. Associated plants in the oasis woodland include honey mesquite (Prosopis glandulosa), arrow weed, and deer grass.

The largest plant category in the national monument is collectively known as desert scrub and includes Sonoran Cresosote Scrub and Sonoran Mixed Woody and Succulent Scrub vegetation communities. Desert scrub occupies more than 160,000 acres (650 km2) and consists of creosote bush (Larrea tridentata), burrobrush (Ambrosia dumosa), cacti, and other stem succulents. Desert scrub is found on the alluvial fans and intermountain bajadas, growing on coarse, well-drained soils. Wildlife of the desert scrub plant community include the federally protected Peninsular Ranges bighorn sheep (Ovis canadensis nelsoni), and the desert tortoise (Xerobates (or Gopherus) agassizii).

On both sides of the mountains, montane coniferous forest occur from around 5,500 to 9,000 feet (2,700 m) in elevation. Vegetation in this area includes Jeffery pine, ponderosa pine, incense cedar, and sugar pine.

Rare plants in the national monument include Hidden Lake bluecurls, Trichostema austromontanum ssp. compactum (federally listed as threatened, 1998), and found at a single vernal pool site, Nuttall's scrub oak, desert sand verbena, Yucaipa onion, and vanishing wild buckwheat.

There are 19 species endemic to the Santa Rosa and San Jacinto Mountains National Monument area. These species require or are restricted to a small geographical area which makes them vulnerable from any habitat disturbance. A few of these species are: Johnston's rockcress, Casey's June beetle, Coachella Valley round-tailed ground squirrel, Munz's mariposa lily, Pratt's dark aurora blue butterfly, San Jacinto bush snapdragon, Santa Rosa Mountain linanthus, Tahquitz ivesia, and Ziegler’s aster.

The Bureau of Land Management lists eight animal species within the monument as endangered, threatened or rare. Of these, all but one are federally listed with the southern rubber boa being state-listed as threatened. In addition to the Peninsular bighorn sheep and the desert tortoise, some of these protected wildlife include the Coachella Valley fringe-toed lizard and the Southwestern willow flycatcher.