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Draft. A draft ecological site description is either incomplete or has not undergone quality control and quality assurance review.
Table 1. Dominant plant species
Tree (1) Pinus monophylla
Shrub (1) Artemisia arbuscula
Herbaceous (1) Poa fendleriana
(2) Achnatherum pinetorumPhysiographic features
This forest community occurs on mountain and hill summits and sideslopes on all aspects. Slope gradients typically range from 8 to over 50 percent. Elevations are 7400 to about 8200 feet.
Table 2. Representative physiographic features
Landforms (1) Ridge
(2) Mountain
Elevation 7596 – 9200 ft Slope 8 – 50 % Aspect Aspect is not a significant factor Climatic features
Average annual precipitation is 12 to about 16 inches. Mean annual air temperature is 44 to 48 degrees F. The average frost-free period is 80 to 110 days.
Table 3 Representative climatic features
Frost-free period (average) 110 days Freeze-free period (average) 0 days Precipitation total (average) 20 in BarLineFigure 1. Monthly precipitation range
BarLineFigure 2. Monthly average minimum and maximum temperature
">Influencing water features
There are no influencing water features associated with this site.
Soil features
These soils of this forest site are shallow to very shallow and well drained. These soils are skeletal, with 35 to 50 percent gravels, cobbles, or stones, by volume, distributed throughout the soil profile. Available water capacity is low or very low, but trees and shrubs extend their roots into fractures in the bedrock allowing them to utilize deep moisture. There may be high amounts of gravels, cobbles or stones at the soil surface which occupy plant growing space yet help to reduce evaporation and conserve soil moisture. Coarse fragments on the soil surface provide a stabilizing affect on surface erosion conditions. Runoff is medium and the potential for sheet and rill erosion is moderate to severe depending on steepness of slope and amount of rock fragments on the soil surface. Soil temperature regime is frigid and soil moisture regime is xeric. The soil series associated with this site is Bellenmine.
Table 4. Representative soil features
Surface texture (1) Very stony sandy loam
(2) Very gravelly clay loam
Drainage class Well drained Permeability class Moderately slow Soil depth 14 – 20 in Surface fragment cover <=3" 30 – 42 % Surface fragment cover >3" 16 – 30 % Available water capacity
(0-40in)1.8 – 1.9 in Calcium carbonate equivalent
(0-40in)Not specified Electrical conductivity
(0-40in)Not specified Sodium adsorption ratio
(0-40in)Not specified Soil reaction (1:1 water)
(0-40in)6.1 – 7.3 Subsurface fragment volume <=3"
(Depth not specified)29 – 44 % Subsurface fragment volume >3"
(Depth not specified)9 – 15 % Ecological dynamics
Major Successional Stages of Forestland Development
HERBACEOUS: Vegetation is dominated by grasses and forbs under full sunlight. This stage is experienced after a major disturbance such as crown fire. Skeleton forest (dead trees) remaining after fire or residual trees left following harvest have little or no affect on the composition and production of the herbaceous vegetation.
SHRUB-HERBACEOUS: Herbaceous vegetation and woody shrubs dominate the site. Various amounts of tree seedlings (less than 20 inches in height) may be present up to the point where they are obviously a major component of the vegetal structure.
SAPLING: In the absence of disturbance, the tree seedlings develop into saplings (20 inches to 4.5 feet in height) with a range in canopy cover of about 5 to 10 percent. Vegetation consists of grasses, forbs and shrubs in association with tree saplings.
IMMATURE FOREST: The visual aspect and vegetal structure are dominated by pinyon trees greater than 4.5 feet in height. The upper crown of singleleaf pinyon are cone or pyramidal shaped. Seedlings and saplings of pinyon are present in the understory. Dominants are the tallest trees on the site. Understory vegetation is moderately influenced by a tree overstory canopy of about 10 to 20 percent.
MATURE FOREST: The visual aspect and vegetal structure are dominated by singleleaf pinyon that have reached or are near maximal heights for the site. Dominant trees average greater than five inches in diameter at one-foot stump. Upper crowns are typically either irregularly or smoothly flat-topped or rounded. Tree canopy cover averages about 25 percent. Understory vegetation is strongly influenced by tree competition, overstory shading, duff accumulation, etc. Infrequent, yet periodic, wildfire is presumed to be a natural factor influencing the understory of mature pinyon forestlands. This stage of community development is assumed to be representative of this forestland site in the pristine environment.
OVER-MATURE FOREST: In the absence of wildfire or other naturally occurring disturbances, the tree canopy on this site can become very dense. At this stage singleleaf pinyon has reached maximal heights for the site. Dominant and co-dominant trees average greater than five inches in diameter at one-foot stump height. Upper crowns are typically irregularly flat-topped or rounded. Understory vegetation is sparse or absent due to tree competition, overstory shading, duff accumulation, etc. Tree canopy cover is commonly greater than 40 percent.
The pinyon-juniper forestland is generally a climax vegetation type throughout its range, reaching climax about 300 years after disturbance, with an ongoing trend toward increased tree density and canopy cover and a decline in understory species over time. Singleleaf pinyon seedling establishment is episodic. Population age structure is affected by drought, which reduces seedling and sapling recruitment more than other age classes. The ecotones between singleleaf pinyon woodlands and adjacent shrublands and grasslands provide favorable microhabitats for singleleaf pinyon seedling establishment since they are active zones for seed dispersal, nurse plants are available, and singleleaf pinyon seedlings are only affected by competition from grass and other herbaceous vegetation for a couple of years.
Several natural and anthropogenic processes can lead to changes in the spatial distribution of pinyon-juniper forestlands over time. These include 1) tree seedling establishment during favorable climatic periods, 2) tree mortality (especially seedlings and saplings) during periods of drought, 3) expansion of trees into adjacent grassland in response to overgrazing and/or fire suppression, and 4) removal of trees by humans, fire, or other disturbance episodes. Specific successional pathways after disturbance in singleleaf pinyon stands are dependent on a number of variables such as plant species present at the time of disturbance and their individual responses to disturbance, past management, type and size of disturbance, available seed sources in the soil or adjacent areas, and site and climatic conditions throughout the successional process.
Fire Ecology:
On high-productivity sites where sufficient fine fuels existed, pinyon-juniper communities burn every 15 to 20 years, and on less productive sites with patchy fuels, fire return intervals may be in the range of 50 to 100 years or longer. Thin bark and lack of self pruning make singleleaf pinyon very susceptible to intense fire. Mature singleleaf pinyon can survive low-severity surface fires but is killed by more severe fires. Most tree seedlings are killed by fire, but cached seeds may survive. Utah juniper is usually killed by fire, especially when trees are small. Utah juniper habitat types rarely have sufficient fine fuels to produce severe or continuous fires. Low sagebrush is very susceptible to fire damage. Low sagebrush is usually killed by fire and does not re-sprout. The recovery in burned areas is usually via small, light, wind-dispersed seed for all low sagebrush subspecies. Partially injured low sagebrush may re-grow from living branches, but sprouting does not occur. Antelope bitterbrush is considered a weak sprouter and is often killed by summer or fall fires. Antelope bitterbrush in some areas may sprout after light-severity spring fires. High fuel consumptions increase antelope bitterbrush mortality and therefore favors seedling establishment. Muttongrass is unharmed to slightly harmed by light-severity fall fires. Muttongrass appears to be harmed by and slow to recover from severe fire. Needlegrasses are damaged by burning due to the dense plant material that can burn slowly and long, charring to the growing points. Late summer and early fall fires are the least harmful.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 textEcosystem states
State 1 submodel, plant communities
State 1
Reference Plant CommunityCommunity 1.1
Reference Plant CommunityThe reference plant community is dominated by singleleaf pinyon and Utah juniper. Low sagebrush is the principal understory shrub. Muttongrass and pine needlegrass are the most prevalent understory grasses. Overstory tree canopy composition is about 80 to 90 percent singleleaf pinyon and less than 20 percent Utah juniper. An overstory canopy cover of about 25 percent is assumed to be representative of tree dominance on this site in the pristine environment.
Forest overstory.MATURE FORESTLAND: The visual aspect and vegetal structure are dominated by singleleaf pinyon that have reached or are near maximal heights for the site. Dominant trees average greater than five inches in diameter at one-foot stump. Upper crowns are typically either irregularly or smoothly flat-topped or rounded. Tree canopy cover averages about 25 percent. Understory vegetation is strongly influenced by tree competition, overstory shading, duff accumulation, etc. Infrequent, yet periodic, wildfire is presumed to be a natural factor influencing the understory of mature pinyon forestlands. This stage of community development is assumed to be representative of this forestland site in the pristine environment.
Forest understory. Understory vegetative composition is about 35 percent grasses, 10 percent forbs and 50 percent 5shrubs and young trees when the average overstory canopy is medium (20 to 30 percent). Average understory production ranges from 250 to 500 pounds per acre with a medium canopy cover. Understory production includes the total annual production of all species within 4.5 feet of the ground surface.
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)Shrub/Vine 95 133 190 Grass/Grasslike 88 123 175 Forb 37 52 75 Tree 30 42 60 Total 250 350 500 Additional community tables
Table 6. Community 1.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Grass/Grasslike1 Primary Perennial Grasses 52–115 muttongrass POFE Poa fendleriana 35–84 – pine needlegrass ACPI2 Achnatherum pinetorum 17–31 – 2 Secondary Perennial Grasses 13–57 Sandberg bluegrass POSE Poa secunda 3–17 – western needlegrass ACOCO Achnatherum occidentale ssp. occidentale 3–17 – Thurber's needlegrass ACTH7 Achnatherum thurberianum 3–17 – squirreltail ELEL5 Elymus elymoides 2–3 – Indian ricegrass ACHY Achnatherum hymenoides 2–3 – Forb3 Perennial 18–77 phlox PHLOX Phlox 3–17 – balsamroot BALSA Balsamorhiza 3–17 – buckwheat ERIOG Eriogonum 3–17 – lupine LUPIN Lupinus 3–17 – beardtongue PENST Penstemon 2–3 – goldenweed PYRRO Pyrrocoma 2–3 – rockcress ARABI2 Arabis 2–3 – Shrub/Vine4 Primary Shrubs 52–115 little sagebrush ARAR8 Artemisia arbuscula 35–84 – antelope bitterbrush PUTR2 Purshia tridentata 17–31 – 5 Secondary Shrubs 9–51 yellow rabbitbrush CHVI8 Chrysothamnus viscidiflorus 3–17 – mormon tea EPVI Ephedra viridis 3–17 – snowberry SYMPH Symphoricarpos 3–17 – Tree6 Deciduous 3–17 curl-leaf mountain mahogany CELE3 Cercocarpus ledifolius 3–17 – 7 Evergreen 20–48 singleleaf pinyon PIMO Pinus monophylla 17–31 – Utah juniper JUOS Juniperus osteosperma 3–17 – Interpretations
Animal community
Livestock Interpretations:
This site is suited to cattle and sheep grazing during the summer and fall. Grazing management should be keyed to muttongrass and needlegrass production. Muttongrass and pine needlegrass, Thurber's, and western needlegrasses provide palatable, nutritious feed during the late spring and summer. New plants of muttongrass and needlegrasses are established entirely from seed and grazing practices should allow for ample seed production and seedling establishment.
Livestock may concentrate on this site taking advantage of the shade and shelter offered by the tree overstory. Many areas are not used because of steep slopes or lack of adequate water. Attentive grazing management is required due to steep slopes and erosion hazards.
Harvesting trees under a sound management program for fuelwood, posts or other products can open up the tree canopy to allow increased production of understory species desirable for grazing.
Stocking rates vary with such factors as kind and class of grazing animal, season of use and fluctuations in climate. Actual use records for individual sites, a determination of the degree to which the sites have been grazed, and an evaluation of trend in site condition offer the most reliable basis for developing initial stocking rates.
Selection of initial stocking rates for given grazing units is a planning decision. This decision should be made ONLY after careful consideration of the total resources available, evaluation of alternatives for use and treatment, and establishment of objectives by the decisionmaker.
The forage value rating is not an ecological evaluation of the understory as is the range condition rating for rangeland. The forage value rating is a utilitarian rating of the existing understory plants for use by specific kinds of grazing animals.
Wildlife Interpretations:
This site has high value for mule deer during the summer, fall and winter. Pinyon trees provide shelter from winter storms. Sites where water is available offer good quail habitat and are visited seasonally by mourning dove. It is also used by various song birds, rodents, reptiles and associated predators natural to the area.Hydrological functions
The hydrologic cover condition of this site is fair in a representative stand. The average runoff curve is about 85 for group C soils and about 90 for group D Soils.
Recreational uses
The trees on this site provide a welcome break in an otherwise open landscape. It has potential for hiking, cross-country skiing, camping, and deer and upland game hunting.
Wood products
Pinyon wood is rather soft, brittle, heavy with pitch, and yellowish brown in color. Singleleaf pinyon has played an important role as a source of fuelwood and mine props. It has been a source of wood for charcoal used in ore smelting. It still has a promising potential for charcoal production. Other important uses for this tree are for Christmas trees and as a source of nuts for wildlife and human food.
PRODUCTIVE CAPACITY
This forestland community is of low site quality for tree production. Site index ranges from 35 to 60 (Howell, 1940).
Productivity Class: 0.2 to 0.4
CMAI*: 2.7 to 6.1 ft3/ac/yr;
0.20 to 0.40 m3/ha/yr.
Culmination is estimated to be at 90 years.
*CMAI: is the culmination of mean annual increment or highest average growth rate of the stand in the units specified.
Fuelwood Production: 4 to 7 cords per acre for stands averaging 5 inches in diameter at 1 foot height with a medium canopy cover. There are about 289,000 gross British Thermal Units (BTUs) heat content per cubic foot of pinyon pine wood and about 274,000 gross BTUs heat content per cubic foot of Utah juniper. Solid wood volume in a cord varies but usually ranges from 65 to 90 cubic feet. Assuming an average of 75 cubic feet of solid wood per cord, there are about 21 million BTUs of heat value in a cord of mixed pinyon pine and Utah juniper.
Posts (7 foot): About 15 to 30 posts per acre in stands of medium canopy.
Christmas trees: Thirty trees per acre per year in stands of medium canopy.
Pinyon nuts: Production varies year to year, but mature woodland stage can yield about 200 pounds per acre (400 to 600 cones per acre) in favorable years.
MANAGEMENT GUIDES AND INTERPRETATIONS
1. LIMITATIONS AND CONSIDERATIONS
a. Potential for sheet and rill erosion is moderate to severe depending on slope.
b. Moderate to severe equipment limitations on steeper slopes and moderate to severe equipment limitations on sites having extreme surface stoniness.
c. Proper spacing is the key to a well managed, multiple use and multi-product pinyon forestland.
2. ESSENTIAL REQUIREMENTS
a. Adequately protect from wildfire.
b. Protect soils from accelerated erosion.
c. Apply proper grazing management.
3. SILVICULTURAL PRACTICES
a. Harvest cut selectively or in small patches size dependent upon site conditions) to enhance forage production.
1) Thinning and improvement cutting - Removal of poorly formed, diseased and low vigor trees for fuelwood.
2) Harvest cutting - Selectively harvest surplus trees to achieve desired spacing. Save large, healthy, full-crowned singleleaf pinyon trees for nut producers. Do not select only "high grade" trees during harvest.
3) Slash Disposal - broadcasting slash improves reestablishment of native understory herbaceous species and establishment of seeded grasses and forbs after tree harvest.
4) Spacing Guide - D+11 (A higher spacing is required if managing for Christmas trees).
b. Prescription burning program to maintain desired canopy cover and manage site reproduction.
c. Mechanical tree removal (i.e. chaining) is not recommended on this site.
d. Pest control - Porcupines can cause extensive damage and populations should be controlled.
e. Fire hazard - Fire usually not a problem in well-managed, mature stands.Other products
The pitch of singleleaf pinyon was used by Native Americans as an adhesive, caulking material, and a paint binder. It may also be used medicinally and chewed like gum. Pinyon seeds are a valuable food source for humans, and a valuable commercial crop.
Other information
Low sagebrush can be successfully transplanted or seeded in restoration. Antelope bitterbrush has been used extensively in land reclamation. Antelope bitterbrush enhances succession by retaining soil and depositing organic material and in some habitats and with some ecotypes, by fixing nitrogen.
Table 7. Representative site productivity
Common name Symbol Site index low Site index high CMAI low CMAI high Age of CMAI Site index curve code Site index curve basis Citation singleleaf pinyon PIMO 35 60 3 6 – – – Supporting information
Type locality
Location 1: Nye County, NV Township/Range/Section T8N R47E S7 General legal description About ¾ mile east of the mouth of Elkhorn Canyon, Monitor Range, Toiyabe National Forest, Nye County, Nevada. This site also occurs in Lincoln County. Other references
Howell, J., 1940. Pinyon and juniper: a preliminary study of volume, growth, and yield. Regional Bulletin 71. Albuquerque, NM: USDA, SCS; 90p.
Jordan, M., 1974. An Inventory of Two Selected Woodland Sites in the Pine Nut Hills of Western Nevada. MS Thesis, UNReno.
USDA-NRCS. 1980. National Forestry Manual - Part 537. Washington, D.C.Contributors
GKB/DSH
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
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Number and extent of rills:
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Presence of water flow patterns:
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Number and height of erosional pedestals or terracettes:
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Bare ground from Ecological Site Description or other studies (rock, litter, lichen, moss, plant canopy are not bare ground):
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Number of gullies and erosion associated with gullies:
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Extent of wind scoured, blowouts and/or depositional areas:
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Amount of litter movement (describe size and distance expected to travel):
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Soil surface (top few mm) resistance to erosion (stability values are averages - most sites will show a range of values):
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Soil surface structure and SOM content (include type of structure and A-horizon color and thickness):
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Effect of community phase composition (relative proportion of different functional groups) and spatial distribution on infiltration and runoff:
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Presence and thickness of compaction layer (usually none; describe soil profile features which may be mistaken for compaction on this site):
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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:
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Amount of plant mortality and decadence (include which functional groups are expected to show mortality or decadence):
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Average percent litter cover (%) and depth ( in):
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Expected annual annual-production (this is TOTAL above-ground annual-production, not just forage annual-production):
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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:
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Perennial plant reproductive capability:
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