Section M261G
Modoc Plateau

Geomorphology.  Northwesterly trending fault-block mountains and ridges with intervening basin-like grabens commonly interspersed with lake bed deposits, shield volcanoes, cinder cones or lava flows.  Modoc Plateau geomorphic province (part of the Basin and Range province flooded with volcanics related to those of the Cascade Ranges province).

Lithology.  Cenozoic volcanic and nonmarine sedimentary rocks and alluvial deposits.

Soil Taxa.  Alfisols, Andisols, Aridisols, Entisols, Histisols, Inceptisols, Mollisols and Vertisols in combination with mesic, frigid or cryic soil temperature regimes and xeric, aquic or aridic soil moisture regimes.

Vegetation.  Predominant potential natural communities include the Big sagebrush series, Western juniper series, Idaho fescue series, Bluebunch wheatgrass series, Ponderosa pine series, White fir series, Low sagebrush series, Jeffrey pine series, Lodgepole pine series, Aspen series and sedge meadow communities.

The following series are found throughout the section and are not restricted to or extensive in any subsection.  Series dominated by exotic plants are not listed under subsections unless they are extensive and stable.

Series dominated by exotic plants: Cheatgrass series, Crested wheatgrass series, Introduced perennial grassland series and Kentucky bluegrass series.
Series that can occur in all subsections, but are not extensive: Bulrush series, Bulrush - cattail series, Bur-reed series, Cattail series, Duckweed series, Mosquito fern series, One-sided bluegrass series, Pondweeds with floating leaves series, Pondweeds with submerged leaves series, Sedge series, Spikerush series and Yellow pond-lily series.
Series restricted to riparian settings: Arroyo willow series, Black cottonwood series, Mixed willow series, Montane wetland shrub habitat, Narrowleaf willow series, Mixed willow series, Red willow series and Subalpine wetland shrub habitat.

Elevation.  3000 to 9900 feet.

Precipitation.  8 to 30 inches.

Temperature.  35° to 52°F.

Growing Season.  25 to 150 days.

Surface Water Characteristics.  Few slow flowing rivers and few slow to moderately rapid flowing streams, although most streams do not flow throughout the summer.  Rivers and streams flow in alluvial and bedrock controlled channels to the Sacramento and Klamath Rivers, or to basins within the Modoc Plateau or the Northwestern Basin and Range section.  Numerous small to very large lakes and reservoirs occur throughout the section.

Disturbance Regimes.

Fire: Historic occurrence has changed from frequent, low intensity ground fires to infrequent, high intensity stand replacing fires.

Cultural Ecology.  Humans have been utilizing the plateau for about 10,000 years, and have been an integral part of its ecology for 3,000 to 5,000 years.  Extensive prehistoric procurement and processing of obsidian resources have left vast areas of the plateau pockmarked and littered with lithic debitage.  Euroamerican influx into the area in the mid-1800’s, along the Oregon and California Trails, ushered in agricultural pursuits.  Contemporary attitudes and beliefs tend to be dominated by commodity oriented long-time resident values and a rural lifestyle.  The economy is dominated by government employment, but ranching and lumbering continue to be important.

Subsections.  The Modoc Plateau Section is divided into 16 subsections.