Ecological Sections: Sierra Nevada - (MAP)
This subsection comprises the mountainous terrain just east of the crest
of the Sierra Nevada, from the south end of the Carson Range southeastward
to the West Walker River near Antelope Peak. It has a cold and subhumid
climate. MLRA 22e.
Lithology and Stratigraphy. Mesozoic granitic and
post-batholith volcanic rocks predominate in this subsection; pre-batholith
rocks are sparse. The volcanic rocks are mostly Pliocene andesite
and lahars. The pre-batholith rocks are mostly undifferentiated metamorphic
rocks. There are small areas of Pleistocene glacial till and outwash
and Quaternary alluvium.
This subsection is characterized by
steep to very steep mountains. Glacial erosion has modified much
of the subsection. Cirques, aretes, cols, and horns are
The rivers flow through both very steep sided V-shaped canyons and
canyons. Alluvial basin floors are more extensive in the U-shaped
canyons. The elevation ranges from about 6000 to 9000 feet,
up to 10023 on Hawkins Peak and 10,241 feet on Antelope Peak.
Mass wasting and fluvial erosion are the main geomorphic
Pleistocene glaciation greatly modified the landscape.
Soils. The soils are mostly Andic Xerumbrepts, Ultic Haploxeralfs,
Lithic Ultic Argixerolls, and Andic Xerochrepts, plus shallow Typic Xeropsamments
on granitic rocks. Soils at the higher elevations are mostly Lithic
and Andic Cryumbrepts, plus shallow Typic Cryopsamments on granitic rocks.
The soils are mostly well drained. Soil temperature regimes are mostly
frigid, but some are cryic. Soil moisture regimes are mostly xeric.
Soils have udic moisture regimes where snow persists through spring, melting
to keep soils moist through much of the summer. Soils with
aquic moisture regimes are present in glaciated terrain and small valleys,
but they are not extensive.
Vegetation. The predominant natural plant communities
are Jeffrey pine series, White fir series, Mixed subalpine forest series,
and Red fir series. Lodgepole pine series occurs on some wet soils, and
on drier soils where cold air drainage and frost limit the regeneration
of other conifers. Singleleaf pinyon, Utah juniper, and Big sagebrush
series prevail at lower elevations. Aspen series is common where
drifted snow accumulates and provides water during summer. Sedge
meadow communities are not extensive.
Characteristic series by lifeform include:
Climate. The mean annual precipitation is about 35 to 45 inches;
most of it falls as snow. Mean annual temperature is about 35°
to 45° F. The mean freeze-free period is in the range from
25 to 75 days.
Grasslands: Ashy ryegrass series, Fen habitat, Nebraska sedge
series, Montane meadow habitat, Mountain heather - bilberry series, Needle-and-thread
series, Rocky Mountain sedge series, Rothrock sagebrush series, Shorthair
reedgrass series, Shorthair sedge series, Subalpine meadow habitat.
Shrublands: Big sagebrush series, Bitterbush series, Greenleaf
manzanita series, Low sagebrush series, Parry rabbitbrush series, Rubber
rabbitbrush series, Subalpine upland shrub habitat, Subalpine wetland shrub
habitat, Tobacco brush series.
Forests and woodlands: Aspen series, Jeffrey pine series, Lodgepole
pine series, Mixed subalpine forest series, Red fir series, Western white
pine series, White fir series, Whitebark pine series.
Surface Water. Runoff is rapid from most of the area.
It flows to the Carson or Walker Rivers. Maximum flow in these rivers
is during spring when snow is melting rapidly. There are many small
natural lakes or ponds in glaciated terrain.