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Ecological site R022AY032NV

ALPINE RIDGE

Accessed: 08/22/2026

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General information

Draft. A draft ecological site description is either incomplete or has not undergone quality control and quality assurance review.

Associated sites

R026XY028NV	MOUNTAIN RIDGE
R026XY075NV	GRAVELLY MOUNTAIN SHOULDERS 16+ P.Z.
R026XY110NV	GRAVELLY SOUTH SLOPE 16+ P.Z.

R026XY028NV

MOUNTAIN RIDGE

R026XY075NV

GRAVELLY MOUNTAIN SHOULDERS 16+ P.Z.

R026XY110NV

GRAVELLY SOUTH SLOPE 16+ P.Z.

Table 1. Dominant plant species

Tree	Not specified
Shrub	Not specified
Herbaceous	(1) Achnatherum occidentale ssp. occidentale (2) Achnatherum lettermanii

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Physiographic features

This site occurs on high wind swept mountain ridges in relatively unstable talus slopes or scree. Slopes range from 2 to over 50 percent, but slope gradients of 2 to 15 are most typical. Elevations are 9000 to over 10,500.

Table 2. Representative physiographic features

Landforms	(1) Ridge (2) Mountain
Flooding frequency	None
Elevation	9000 – 10500 ft
Slope	2 – 50 %
Aspect	Aspect is not a significant factor

Climatic features

The climate associated with this site is semiarid, characterized by cold, moist winters and warm, somewhat dry summers. Average annual precipitation is 20 inches to over 40 inches. The linear to convex slope shapes associated with this site causes some of the precipitation that occurs as snowfall to be removed from the site because of wind action, thus reducing the moisture available for plant growth. Mean annual air temperature is 33 to 38 degrees F. The average growing season is about 15 to 45 days.

Table 3 Representative climatic features

Frost-free period (average)	50 days
Freeze-free period (average)	0 days
Precipitation total (average)	60 in

Bar

Line

Figure 1. Monthly precipitation range

Bar

Line

Figure 2. Monthly average minimum and maximum temperature

Soil features

The soils that support this site are typically very shallow to deep and are well to somewhat excessively drained. They formed in residduum and colluvium derived from volcanic or granitic rocks or from mixed glacial till. Surface layers are coarse to moderately coarse textured with greater than 35 percent rock fragments. Subsoil layers range from coarse to moderately fine textured with greater than 35 percent rock fragments. The overiding feature that effects the ecology of this site is the very cold soil and air temperatures. The soils associated with this site are classified as Typic Cryorthents.

Table 4. Representative soil features

Parent material	(1) Residuum – granite
Surface texture	(1) Extremely gravelly sandy loam (2) Very gravelly loamy coarse sand
Drainage class	Well drained to somewhat excessively drained
Soil depth	7 – 60 in
Surface fragment cover <=3"	35 – 60 %
Surface fragment cover >3"	10 – 20 %
Available water capacity (0-40in)	0.5 – 6 in
Electrical conductivity (0-40in)	0 – 2 mmhos/cm
Soil reaction (1:1 water) (0-40in)	4.5 – 7.3
Subsurface fragment volume <=3" (Depth not specified)	35 – 60 %
Subsurface fragment volume >3" (Depth not specified)	10 – 20 %

Ecological dynamics

This site is dominated by low growing forb and graminoid species. It is found a high elevations, above timberline, in areas exposed to extreme winter conditions. Canopy cover is sparse and low to the ground. The species composition varies widely across this ecological site, vegetation is patchy with open talus areas in between. Environmental conditions which may influence the distribution of vegetation include the stability of the soil, location of snow drifts, and the impact from wind.

Climate change predictions from global warming indicate that this community could be at high risk for extinction. Warmet temperatures would force this community up in elevation, where there is even less soil and more rock.

Fire Effects:
Perennial needlegrasses tend to be among the least fire resistant bunchgrass due to the densely tufted stems. Western needlegrass is only slightly to moderately damaged by fire, because it has relatively few culms per clump which may help to minimize the amount of subsurface heat transfer and subsequent damage.
Little specific information is available on adaptations of Letterman's needlegrass to fire. It is morphologically similar to Columbia needlegrass, which is only slightly to moderately damaged by fire. Season of burn affects the plant's ability to survive a fire. Needle grass tends to be more susceptible to fire when burned during mid-summer. Post fire regeneration is through seeding and tillering.

State and transition model

More interactive model formats are also available. View Interactive Models
Click on state and transition labels to scroll to the respective text

Ecosystem states

1. Reference State

State 1 submodel, plant communities

1.1. Reference Plant Community

State 1
Reference State

Community 1.1
Reference Plant Community

The reference plant community is found above the timberline on exposed ridges and peaks. The vegetation in this landscape could be mistaken for mosses and lichens at first glance, due to the extremely compact and prostrate growth form of this community. Common forbs are dwarf alpine paintbrush, fewseed draba, rosy buckwheat, dwarf phlox, and Nevada postera. Grasses include needlegrass, squirreltail, bluegrasses, and spike trisetum. The vegetation is patchy with open non-vegetated rubble land in-between. Vegetative composition is about 45% grasses, 45% forbs, and 10% shrubs. Approximate ground cover is 5 to 20 percent.

Figure 3. Annual production by plant type (representative values) or group (midpoint values)

Table 5. Annual production by plant type

Plant type	Low (lb/acre)	Representative value (lb/acre)	High (lb/acre)
Grass/Grasslike	22	67	135
Forb	23	68	135
Shrub/Vine	5	15	30
Total	50	150	300

Additional community tables

Table 6. Community 1.1 plant community composition

Group	Common name	Symbol	Scientific name	Annual production ()	Foliar cover (%)
Grass/Grasslike
1	Perennial Grasses			53–75
	Letterman's needlegrass	ACLE9	Achnatherum lettermanii	1–8	–
	western needlegrass	ACOCO	Achnatherum occidentale ssp. occidentale	1–8	–
	mountain brome	BRMA4	Bromus marginatus	1–8	–
	sedge	CAREX	Carex	1–8	–
	big squirreltail	ELMU3	Elymus multisetus	1–8	–
	spike fescue	LEKI2	Leucopoa kingii	1–8	–
	rock melicgrass	MEST	Melica stricta	1–8	–
	muttongrass	POFE	Poa fendleriana	1–8	–
	Sandberg bluegrass	POSE	Poa secunda	1–8	–
Forb
2	Perennial Forbs			53–75
	rockcress	ARABI2	Arabis	1–8	–
	tapertip hawksbeard	CRAC2	Crepis acuminata	1–8	–
	buckwheat	ERIOG	Eriogonum	1–8	–
	lupine	LUPIN	Lupinus	1–8	–
	phlox	PHLOX	Phlox	1–8	–
	sedge	CAREX	Carex	1–3	–
Shrub/Vine
3	Shrubs			3–12
	Utah serviceberry	AMUT	Amelanchier utahensis	1–5	–
	mountain big sagebrush	ARTRV	Artemisia tridentata ssp. vaseyana	1–5	–
	slender buckwheat	ERMI4	Eriogonum microthecum	1–5	–
	Davidson's penstemon	PEDA2	Penstemon davidsonii	1–5	–
	currant	RIBES	Ribes	1–5	–
	roundleaf snowberry	SYRO	Symphoricarpos rotundifolius	1–5	–

Interpretations

Animal community

Livestock Interpretations:
This site is not suited to livestock grazing due to the low forage production.

Wildlife Interpretations:
Migratory birds and small mammals visit and utilize this area.

Hydrological functions

Runoff is high to very high.

Recreational uses

Hiking and mountain biking is the main recreation for this site.

Wood products

None

Other products

None

Other information

Letterman’s needlegrass has been used successfully in revegetating mine spoils. This species also has good potential for erosion control.

Trails should be properly designed to reduce erosion and keep hikers on the designated trails. Several plant species of special concern are found in this community.

Supporting information

Type locality

Location 1: Alpine County, CA
Latitude	38° 25′ 37″
Longitude	119° 17′ 55″
General legal description	Toyaibe National Forest

Other references

Braasch, Gary (1999-2005) Pushing the Boundaries of Life: Mid-latitudes. In:World View of Global Warming. Global Warming in the Temperate zone. http://www.worldviewofglobalwarming.org/pages/temperate-zone.html

Fire Effect Information System (Online; http://www.fs.fed.us/database/feis/plants/).

USDA-NRCS Plants Database (Online; http://www.plants.usda.gov).

Contributors

ALC/GKB

Rangeland health reference sheet

Interpreting Indicators of Rangeland Health is a qualitative assessment protocol used to determine ecosystem condition based on benchmark characteristics described in the Reference Sheet. A suite of 17 (or more) indicators are typically considered in an assessment. The ecological site(s) representative of an assessment location must be known prior to applying the protocol and must be verified based on soils and climate. Current plant community cannot be used to identify the ecological site.

Author(s)/participant(s)
Contact for lead author
Date
Approved by
Approval date
Composition (Indicators 10 and 12) based on	Annual Production

Indicators

Number and extent of rills:
Presence of water flow patterns:
Number and height of erosional pedestals or terracettes:
Bare ground from Ecological Site Description or other studies (rock, litter, lichen, moss, plant canopy are not bare ground):
Number of gullies and erosion associated with gullies:
Extent of wind scoured, blowouts and/or depositional areas:
Amount of litter movement (describe size and distance expected to travel):
Soil surface (top few mm) resistance to erosion (stability values are averages - most sites will show a range of values):
Soil surface structure and SOM content (include type of structure and A-horizon color and thickness):
Effect of community phase composition (relative proportion of different functional groups) and spatial distribution on infiltration and runoff:
Presence and thickness of compaction layer (usually none; describe soil profile features which may be mistaken for compaction on this site):
Functional/Structural Groups (list in order of descending dominance by above-ground annual-production or live foliar cover using symbols: >>, >, = to indicate much greater than, greater than, and equal to):

Dominant:

Sub-dominant:

Other:

Additional:
Amount of plant mortality and decadence (include which functional groups are expected to show mortality or decadence):
Average percent litter cover (%) and depth ( in):
Expected annual annual-production (this is TOTAL above-ground annual-production, not just forage annual-production):
Potential invasive (including noxious) species (native and non-native). List species which BOTH characterize degraded states and have the potential to become a dominant or co-dominant species on the ecological site if their future establishment and growth is not actively controlled by management interventions. Species that become dominant for only one to several years (e.g., short-term response to drought or wildfire) are not invasive plants. Note that unlike other indicators, we are describing what is NOT expected in the reference state for the ecological site:
Perennial plant reproductive capability:

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