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Ecological site F048AY448CO

Mountain Pinyon

Last updated: 3/05/2024
Accessed: 12/11/2024

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General information

Provisional. A provisional ecological site description has undergone quality control and quality assurance review. It contains a working state and transition model and enough information to identify the ecological site.

MLRA notes

Major Land Resource Area (MLRA): 048A–Southern Rocky Mountains

MLRA 48A makes up about 45,920 square miles (119,000 square kilometers) and is the southern part of the Rocky Mountains. The Southern Rocky Mountains lies east of the Colorado Plateau, south of the Wyoming Basin, west of the Great Plains, and north of the Rio Grande Rift. It is in western and central Colorado, southeastern Wyoming, eastern Utah and northern New Mexico. The headwaters of major rivers such as the Colorado, Yampa, Arkansas, Rio Grande, North Platte and South Plate rivers are located here. This MLRA has numerous national forests, including the Medicine Bow National Forest in Wyoming; the Routt, Arapaho, Roosevelt, Pike, San Isabel, White River, Gunnison, Grand Mesa, Uncompahgre, Rio Grande, and San Juan National Forests in Colorado; the Carson National Forest and part of the Santa Fe National Forest in New Mexico. Rocky Mountain National Park also is in this MLRA.

MLRA 48A is the southern Rocky Mountains physiographic region. The Southern Rocky Mountains consist primarily of two belts of strongly sloping to precipitous mountain ranges trending north to south. Several basins, or parks, are between the belts. Some high mesas and plateaus are included. It is characterized by mountain ranges that were uplifted during the Laramide Orogeny and then had periods of glaciation. The ranges include the Sangre de Cristo Mountains, the Laramie Mountains, and the Front Range in the east and the San Juan Mountains and the Sawatch and Park Ranges in the west. The ranges are dissected by many narrow stream valleys having steep gradients. In some areas the upper mountain slopes and broad crests are covered by snowfields and glaciers. Elevation typically ranges from 6,500 to 14,400 feet (1,980 to 4,390 meters) in this area. The part of this MLRA in central Colorado includes the highest point in the Rockies, Mount Elbert, which reaches an elevation of 14,433 feet (4,400 meters). More than 50 peaks in the part of the MLRA in Colorado are at an elevation of more than 14,000 feet (4,270 meters). Many small glacial lakes are in the high mountains.

The mountains in this area were formed mainly by crustal uplifts during the late Cretaceous and early Tertiary periods. This large MLRA can be subdivided into at least 4 large general divisions. First is the Rockies on the east side of this area are called the “Front Range,” which is a fault block that has been tilted up on edge and uplifted and is largely igneous and metamorphic geology. It was tilted up on the east edge, so there is a steep front on the east and the west side is more gently sloping and in the south east there are rocks exposed in the mountains are mostly Precambrian igneous and metamorphic rocks. Second is the tertiary rocks, primarily basalt and andesitic lava flows, tuffs, breccias, and conglomerates, are throughout this area (San Juan Mountains Area). The third division is Northwest part of the MLRA is dominantly sedimentary rock from the cretaceous/tertiary and Permian/ Pennsylvanian periods. The fourth subset is the long and narrow Sangre de Cristos mountains uplifted in the Cenozoic are between the Rio Grande rift and the great plains. Many of the highest mountain ranges were reshaped by glaciation during the Pleistocene. Alluvial fans at the base of the mountains are recharge zones for local basin and valley fill aquifers. They also are important sources of sand and gravel.

The average annual precipitation ranges predominantly from 12 to 63 inches. Summer rainfall commonly occurs as high-intensity, convective thunderstorms. About half of the annual precipitation occurs as snow in winter; this proportion increases with elevation. In the mountains, deep snowpacks accumulate throughout the winter and generally persist into spring or early summer, depending on elevation. Some permanent snowfields and small glaciers are on the highest mountain peaks. In the valleys at the lower elevations, snowfall is lighter and snowpacks can be intermittent. The average annual temperature is 26 to 54 degrees F (-3 to 12 degrees C). The freeze-free period averages 135 days and ranges from 45 to 230 days, decreasing in length with elevation. The climate of this area is strongly dependent upon elevation; precipitation is greater, and temperatures are cooler at the higher elevations. The plant communities vary with elevation, aspect and change in latitudes due to changing in precipitation kind and timing and temperature.

The dominant soil orders in this MLRA are Mollisols, Alfisols, Inceptisols, and Entisols. The soils in the area dominantly have a frigid or cryic soil temperature regime and an ustic or udic soil moisture regime. Mineralogy is typically mixed, smectitic, or paramicaceous. In areas with granite, gneiss, and schist bedrock, Glossocryalfs (Seitz, Granile, and Leadville series) and Haplocryolls (Rogert series) formed in colluvium on mountain slopes. Dystrocryepts (Leighcan and Mummy series) formed on mountain slopes and summits at the higher elevations. In areas of andesite and rhyolite bedrock, Dystrocryepts (Endlich and Whitecross series) formed in colluvium on mountain slopes. In areas of sedimentary bedrock, Haplustolls (Towave series) formed on mountain slopes at low elevations and with low precipitation. Haplocryolls (Lamphier and Razorba series), Argicryolls (Cochetopa series), and Haplocryalfs (Needleton series) formed in colluvium on mountain slopes at high elevations.

Classification relationships

NRCS & BLM: Major Land Resource Area 36, Southwestern Plateaus Mesas and Foothills (United States Department of Agriculture, Natural Resources Conservation Service, 2006).

USFS:
341Bp - Uncompahgre Plateau and 341Bg - Northeast Flank Subsections <341B Northern Canyonlands Section < 341 Intermountain Semi-desert and Desert (Cleland, et al., 2007).

M331Gc - Gunnison Basin-Black Canyon M331G South Central Highlands Section M331 Southern Rocky Mountain Steppe - Open Woodland - Coniferous Forest - Alpine Meadow (Cleland, et al., 2007).

EPA:
20b Shale Deserts and Sedimentary Basins and 20c Semiarid Benchlands and Canyonlands, < 20 Colorado Plateau < 10.l Cold Deserts < 10 North American Deserts (Griffith, 2006).

USGS: Colorado Plateau Province (Canyonlands Section)

Ecological site concept

Mountain Pinyon occurs on mountains, ridges, hills, hillslopes and structural benches. Slopes is between 3 to 30%. Soils are very shallow to shallow (5 to 20 inches) in depth. Soils are derived from colluvium, residuum, slope alluvium from sandstone and/or siltstone. Soil surface texture is loam, gravelly to gravelly loam, channery loam or sandy loam with a loamy or loamy skeletal subsurface. It is a Two-needle pinyon – Gambel’s oak – western wheatgrass community. It has an aridic ustic moisture regime and a frigid temperature regime. The effective precipitation ranges from 12 to 16 inches.

Associated sites

R036XY284CO	Loamy Foothills Loamy Foothills occurs on hills, benches and mesas on moderately deep to deep loamy textured soils derived from alluvium, slope alluvium eolian deposits, and colluvium. It is a Wyoming big sagebrush – Muttongrass community. It has an aridic ustic moisture regime and mesic temperature regime. The effective precipitation ranges from 12 to 16 inches.
R048AY238CO	Brushy Loam Brushy Loam occurs on hills, mountains, complex landslides, and benches. Slopes is between 3 to 35%. Soils are moderately deep to deep (20 to 60+ inches), soils derived from colluvium, residuum, slope alluvium and alluvium from sandstone and shale. Soil surface texture is loam or clay loam with fine-textured subsurface. It is a Gambel’s oak – slender wheatgrass community. It has a typic ustic moisture regime. The effective precipitation ranges from 16 to 20 inches
R036XY289CO	Clayey Foothills Clayey Foothills occurs on benches, foot-slopes, fans, and valley. Soils are moderately deep to deep and have marine shale as parent materials. The soil textures are clay loam to clay. Dominant plants are Wyoming Big Sagebrush and western wheatgrass. This site has a high potential for shrink swell.
R048AY287CO	Stony Foothills Stony Foothills occurs on mountains, escarpments and hills. Slopes is between 3 to 30%. Soils are moderately deep to deep (20 to 60+ inches). Soils are derived from alluvium, residuum or colluvium from sandstone and shale or alluvium from basalt. Soil surface texture is gravelly, stony, or very stony sandy loam or very cobbly loam with loamy-skeletal textured subsurface. It is a Wyoming Big Sagebrush – western wheatgrass community. It has a aridic ustic moisture regime and frigid temperature regime. The effective precipitation ranges from 12 to 16 inches.

Similar sites

R048AY240CO	Shallow Pine Shallow Pine occurs on mountains and mountainsides. Slopes are 5 to 50%. Soils are shallow (10 to 20 inches). Soils are derived from slope alluvium from volcanic breccia, gneiss, granite, or sandstone and/or residuum from granite, granodiorite and/or gneiss. Soil surface texture is a gravelly to very gravelly sandy loam or very gravelly loam with loamy-skeletal subsurface. It is a Ponderosa Pine - Arizona Fescue – Mountain Muhly community. It has a typic ustic moisture regime. The effective precipitation ranges from 16 to 20 inches.
R048AY230CO	Shallow Loam Shallow Loam occurs on mountains, and hills. Soils are very shallow to shallow (less than 20 inches) loamy-skeletal soils derived from slope alluvium from trachyte, volcanic breccia, gneiss, granite and/or sandstone; residuum from weathered volcanic breccia, tuff, igneous rock, sandstone or sandstone and shale. Soils surface textures are gravelly to very gravelly loam, gravelly to very gravelly sandy loam, cobbly loam. Or very cobbly sandy loam. It is an Arizona Fescue-Mountain Muhly community with scattered mountain mahogany, snowberry and current. It has a typic ustic moisture regime. The effective precipitation ranges from 16 to 20 inches.
R036XY114CO	Mountain Pinyon Mountain Pinyon is a gentle sloped (<25% slope) site with very shallow and shallow soils that are loamy in texture. This site is dominated by Pinyon, Utah Juniper. This site may have oakbrush in the understory. This site is in the 12 to 16 inch precipitation zone of foothills/upland. This is the mesic temperature verison of F048AY448CO - Mountain Pinyon which is frigid.
R036XY287CO	Stony Foothills Stony Foothill is a gentle sloped (<25% slope) site with moderately deep to deep that are loamy-skeletal in texture. This site is dominated by Pinyon, Utah Juniper. This site may have oakbrush in the understory. This site is in the 12 to 16 inch precipitation zone of foothills/upland.
R036XY346CO	Cobbly Foothills Cobbly Foothill is a gentle sloped (<20% slope) site with moderately deep to deep soils that are loamy-skeletal in texture. Common surface textures are cobbly or gravelly loam. This site is dominated by Big sagebrush, western wheatgrass, Pinyon, and Utah Juniper. This site is in the 12 to 16 inch precipitation zone of foothills/upland.
R036XY142CO	Loamy Mesa Top (pinyon-Utah juniper) Loamy Mesa Top is a gentle sloped (<15% slope) site with moderately deep to deep soils that are coarse loamy in texture. This site is shallow to calcic horizon. The typical profile is border-line skeletal which reduces the water holding capacity of this site. It is dominated by Pinyon, Utah Juniper, muttongrass and Indian ricegrass. This site is in the 15 to 18 inch precipitation zone of foothills/upland.
R036XY141CO	Shallow Loamy Mesa Top (pinyon-Utah juniper) Shallow Loamy Mesa Top is a gentle sloped (<25% slope) site with very shallow and shallow soils that are loamy in texture. This site is dominated by Pinyon, Utah Juniper, muttongrass and Indian ricegrass. This site is in the 15 to 18 inch precipitation zone of foothills/upland
R036XY445CO	Steep Colluvial Slopes Steep Colluvial Slopes is a very steep (>25% slope) sloped site with very shallow to shallow soils that are clayey in texture. This site is dominated by Utah Juniper and pinyon. This site may have Wyoming big sagebrush in the understory. This site has higher precipitation (12 to 16 inches)
R036XY446CO	Southwestern Mountain (pinyon-Utah juniper) Southwestern Mountain (Pinyon-Juniper) is a gentle sloped (<25% slope) site with very shallow and shallow soils that are loamy or loamy-skeletal in texture. This site is dominated by Pinyon, Utah Juniper, Wyoming big sagebrush, muttongrass and Indian ricegrass. This site may have oakbrush in the understory. This site is in the 12 to 16 inch precipitation zone of foothills/upland.
R048AY218CO	Dry Shallow Pine Shallow Pine occurs on mountains, hills, and mountainside. Slopes is between 5 to 35%. Soils are shallow (10 to 20 inches) in depth. Soils are derived from slope alluvium from monzonite or gneiss or from residuum from granite, gneiss or granodiorite. Soil surface texture is very gravelly sandy loam with a loamy skeletal subsurface. It is a Gambel’s oak – Mountain muhly community. It has an typic ustic moisture regime. The effective precipitation ranges from 16 to 20 inches.

Table 1. Dominant plant species

Tree	(1) Pinus edulis (2) Juniperus utahensis
Shrub	(1) Quercus gambelii
Herbaceous	(1) Pascopyrum smithii (2) Achnatherum hymenoides

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Physiographic features

This site occurs on mountain slopes, ridges, and hills. Slopes typically range from 3-30 percent, and elevations are generally 6000-8000 feet.

Table 2. Representative physiographic features

Landforms	(1) Mountain (2) Ridge (3) Hill (4) Hillslope (5) Structural bench
Runoff class	High to very high
Flooding frequency	None
Ponding frequency	None
Elevation	1,829 – 2,438 m
Slope	3 – 45%
Aspect	Aspect is not a significant factor

Climatic features

Average annual precipitation is about 12 to 16 inches. Of this, approximately 45-55% falls as snow, and 45-55% falls as rain between middle of May to and the end of September. Summer moisture is mostly from thundershowers in July thru October. November to February and June is the driest period of the year with the driest month being June. August to October and March to April is the wettest period and the wettest month is usually April. The average annual total snowfall is 64.8 inches. The snow depth usually ranges from 1 to 5 inches during October thru April. The highest winter snowfall record in this area is 131.9 inches which occurred in 1908-1909. The lowest snowfall record is 11.9 inches during the 1944-1945 winter. The frost-free period typically ranges from 90 to 130 days. The last spring frost is typically the middle of May to the second week of June. The first fall frost is usually the middle of September to the end of September. Mean daily annual air temperature ranges from about 30.7ºF to 64.8ºF, averaging about 25ºF for the winter and 66ºF in the summer. Summer high temperatures of mid-80ºF to low 80ºF are not unusual. The coldest winter temperature recorded was -36ºF on February 8, 1933 and the warmest winter temperature recorded was 66ºF on February 11, 1962. The coldest summer temperature recorded was 24ºF on June 19, 1973 and the warmest was 100ºF on August 2, 1902. Wide yearly and seasonal fluctuations are common for this climatic zone. Data taken from Western Regional Climate Center (2018) for Collbran, Colorado Climate Station.

This zone in MLRA 48 will need to be broken up into at multiple land resources zones in future projects based on current knowledge of precipitation and temperature patterns.

West Central Zone Stations: Collbran, Basalt, and Cedaredge. This LRU zone is use in write up above. November to February and June is the driest period of the year with the driest month being June. August to October and March to April is the wettest period and the wettest month is usually April. Frigid

Northwest Zone Climate Stations: Meeker#2. Driest months usually are January and February. Wettest months usually are August and September. Frigid.

Southwest Zone Climate Stations (Precambrian sedimentary and igneous): There are no climate stations in this LRU zone.

Southwest Volcanics: Lake City, Creede, and Hermit 7 ESE. These high elevation and low precipitation areas are cryic with shorter growing season days of 20 to 70 days per year. Wettest months are August and July. Driest months are December thru February.

Northeast (Front Range Igneous and Metamorphic): Grant, Estes park, Hohnholz Ranch, Leadville and Leadville 2 SW. July and August are the wettest months. January is the driest month. The climate stations is this zone are cryic. The growing seasons is 50 to 90 days.

Southeast (Sangre de Cristo Mtns): Westcliffe. Red Wing 1 WSW and Sheep Mountain. The growing season is 90 to 140 days. Driest months are December to February and the wettest are July & August. Frigid.

Table 3. Representative climatic features

Frost-free period (characteristic range)	28-98 days
Freeze-free period (characteristic range)	77-131 days
Precipitation total (characteristic range)	330-381 mm
Frost-free period (actual range)	13-111 days
Freeze-free period (actual range)	67-141 days
Precipitation total (actual range)	330-381 mm
Frost-free period (average)	63 days
Freeze-free period (average)	104 days
Precipitation total (average)	356 mm

Characteristic range

Actual range

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Figure 1. Monthly precipitation range

Characteristic range

Actual range

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Figure 2. Monthly minimum temperature range

Characteristic range

Actual range

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Figure 3. Monthly maximum temperature range

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Figure 4. Monthly average minimum and maximum temperature

Figure 5. Annual precipitation pattern

Figure 6. Annual average temperature pattern

Climate stations used

(1) CIMARRON [USC00051609], Cimarron, CO
(2) CEDAREDGE 3 E [USC00051443], Cedaredge, CO
(3) COLLBRAN [USC00051741], Collbran, CO
(4) LEADVILLE LAKE CO AP [USW00093009], Leadville, CO

Soil features

Soils are very shallow to shallow in depth (5-20 inches). The surface soils textures range from fine sandy loam to loam, some gravels may be present on the surface. The subsoils are loamy textured. Subsoils can have so gravels and/cobbles in it. The soil moisture and temperature regimes are ustic aridic and frigid respectively.

Mountain Pinyon has been used as a catchall for PJ sites that don’t fit other ecological sites in this climatic zone. Some soils have been mis-correlated to this site that should be assigned to a different site. Moderately deep and deep skeletal soils need to be evaluated and most likely belong in the Stony Foothills.

Typical soils assigned to this ecological site are:

Loamy – Redcreek, Beenom and Falconry

Loamy-Skeletal - Rentsac, Earsman and Tolman

Table 4. Representative soil features

Parent material	(1) Colluvium – sandstone and siltstone (2) Residuum – sandstone and siltstone (3) Slope alluvium – sandstone (4) Residuum – sandstone
Surface texture	(1) Loam (2) Very gravelly loam (3) Channery loam (4) Sandy loam
Family particle size	(1) Loamy (2) Loamy-skeletal
Drainage class	Well drained
Permeability class	Moderately slow to moderately rapid
Soil depth	5 – 51 cm
Surface fragment cover <=3"	0 – 30%
Surface fragment cover >3"	0 – 15%
Available water capacity (Depth not specified)	2.29 – 7.62 cm
Calcium carbonate equivalent (Depth not specified)	0 – 10%
Electrical conductivity (Depth not specified)	0 – 2 mmhos/cm
Soil reaction (1:1 water) (Depth not specified)	6.6 – 8.4
Subsurface fragment volume <=3" (Depth not specified)	0 – 35%
Subsurface fragment volume >3" (Depth not specified)	0 – 40%

Ecological dynamics

This area has a long history of past prehistoric human use for thousands of years. They used pinyon-juniper woodlands for hunting, fuelwood, for food, such as pinon nuts. MLRA 48A/36 have archaeological evidence indicating pinyon-juniper woodlands where modified by prehistoric humans and not pristine and thus where altered at the time of European settlement (Cartledge & Propper, 1993). This area is characterize by broken topography, and lack of perennial water sources. Most pinyon-juniper in western Colorado and eastern Utah can be describe as a persistent woodland type. There is a winter-summer bimodal precipitation pattern in the Western Colorado. Meaning that this site developed under climatic conditions that include wet, cold winters, and hot, dry summers with summer rains. This area so included natural influences of herbivory, fire, and climate. This area rarely served as habitat for large herds of native herbivores or large frequent historic fires due to the broken topography. The lowest end precipitation and climate of MLRA 48A are conducive to producing Pinyon/juniper, and sagebrush complexes.

Pinyon-Juniper expansion began during the late 1800s into deeper well drained soils. (Tausch et al. 1981, Miller and Tausch, 2001). The causes of woodland expansion are often attributed to an reduction in fires, introduction of livestock grazing, shifts in climate, and increases in atmospheric CO2 (Miller and Rose 1999). Prior to European settlement, PJ woodland species were primarily found on shallow soils and rocky ridges. Few fire history studies and pinyon-juniper chronologies have been done in the southwest. It appears that woodland on the Colorado Plateau are more susceptible to die off from severe drought (Miller and Tausch, 2001). Historically, fires before European settlement in the southwest occurred late spring to mid-summer (Miller and Tausch, 2001).

Historic fire return intervals (300-1000 years) are long, possibly indicating that fire did not play a frequent role in community dynamics. Pinyon and Juniper communities near Mesa Verde were established before European settlement with a fire return interval approximately 400 years (Floyd et al., 2000). Shinneman and Baker (2009) estimated the FRI on the Uncompahgre Plateau to be 400 to 600 years. Mesa Verde (Floyd et al., 2000) and Uncompahgre (Shinneman and Baker, 2009) are in the foothills/upland zone (12 to 16 inches annual precipitation) in MLRA 36. One other known study in the Colorado National Monument on the north eastern part of the Uncompahgre Plateau suggest that lower ecological site zone (semi-desert) (9 to 12 inches of annual precipitation) have a fire return interval of 300 to 1,000 years (Kennard and Moore, 2013). One other difference is that in the semi-desert zone smaller fire of only a few trees maybe more common than the infrequent larger fires found in other studies.

In lower elevations and lower precipitation areas, Utah Juniper maybe dominant over Pinyon. As the precipitation increase and effect moisture increase so will pinyon. The lower end of the pinyon-juniper woodland would be almost entirely Utah Juniper with the reverse happening and pinyon being dominant in the upper end of the pinyon-juniper belt.

The driving factors in Pinyon Juniper woodlands seem to be weather patterns. Drought and insects outbreaks appear to be the main driving factors for mortality in many of the Pinyon/Juniper communities. (Shinneman and Baker, 2009, Floyd et al., 2004) Wet periods seem to enhance and promote pinyon and juniper establishment. Betancourt (1993), noted that Pinyon and Juniper woodlands in the southwest appear to be more susceptible to large die offs during droughts, than in other locations. As severe droughts persist, the Pinyon trees, being more susceptible to drought and insects, seem to die out, while the Utah juniper trees survive. This action could open the canopy for a few years and with sufficient moisture, grasses and forbs would be expected to respond favorably. Two studies illustrated this on the Uncompahgre Plateau found that pinyon began increasing in the 1700s, during a wet period that followed a long dry period. So, tree infill and expansion began before European settlement. Associated fire reduction and livestock grazing effect of European settlers can after the trees started the current expansion. Since the 1900s there has been 2 very wet period in the southwest, during 1900s to 1920s and 1970s to 1990s. These periods saw an increase in Pinon establishment. During the drought of the 1950s and the drought mid-1990s to early 2000s, Pinyon mortality was extensive. (Romme, et al. 2009)

Disturbances such as improper grazing (continuous season long grazing, heavy stocking rates, etc.), recreation activities, etc., can remove herbaceous vegetation and compact the soils. The unpredictability of the annual growing conditions make these communities susceptible to the loss of understory and the resulting accelerated erosion. This ecological site has been grazed by domestic livestock since they were introduced into the area, though grazing has been light due to the lack of water and difficult terrain. The introduction of domestic livestock and the use of fencing and reliable water sources have influenced the disturbance regime of this site. As of this date, invasive annual grasslands that are so common in the Great Basin after a severe disturbance are not as prevalent in MLRA 36, potentially due to the remote location, the climate, and/or the soils.

PJ fire intervals can be influences by the landscape it occurs on. PJ that is complexed with sagebrush site would burn more frequently do to the fine fuels in the sagebrush sites to start the fires. So, the more rough broken terrain would burn less frequently than the gentler and broader landscapes. PJ sites on the Colorado Plateau generally don’t have enough fine fuels to start large scale fires. The exception would be several wet years in a row that would create the fine fuels necessary for a fire to start.

As vegetation communities respond to changes in management or natural occurrences, thresholds can be crossed, which usually means that a return to the previous state may not be possible without major energy inputs. The amount of energy input needed to affect vegetative shifts depends on the present biotic and abiotic features and the desired results.

Pinyon-juniper sites were treated as one vegetation dynamic type when developing the provision ecological site initiative for MLRA 48A. These sites will need to be altered as more data and knowledge in the future becomes available. Variability in climate, soils, aspect and complex biological processes will cause the plant communities to differ. These factors contributing to annual production variability include wildlife use, drought, and insects. Factors contributing to special variability include soil texture, depth, rock fragments, slope, aspect, and micro-topography. The species lists are representative and not a complete list of all occurring or potentially occurring species on this site. The species lists are not intended to cover the full range of conditions, species and responses of the site. The State & Transition model depicted for this site is based on available research, field observations and interpretations by experts and could change as knowledge increases. As more data is collected, some of these plant communities may be revised or removed, and new ones may be added. The following diagram does not necessarily depict all the transitions and states that this site may exhibit, but it does show some of the most common plant communities.

State and transition model

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Standard diagram

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Ecosystem states

1. Reference State

State 1 submodel, plant communities

1.1. Reference State

State 1
Reference State

Community 1.1
Reference State

Additional community tables

Interpretations

Animal community

The following is from 1995 Range Site:

INTERPRETATIONS FOR GRAZING ANIMALS:
When in excellent conditions, this site can be valuable for grazing by livestock. All of the grasses are palatable so they will become less abundant and less vigorous if the site is grazed too heavily. If over grazing continues, total production will be drastically reduced and many species will completely disappear from the site. When this occurs, erosion increases greatly and basal area will become nearly zero.

Adjustment to the initial stocking rate should be made as needed to obtain proper use. With specialized grazing systems, large livestock breeds, uncontrolled big game herbivores inaccessibility, dormant season use, etc., stocking rate adjustments will be required.

Depending on climatic condition, in some years palatable annuals such as cheatgrass may produce large amounts of forage that is available for only a short time. Intensive grazing programs on these areas followed by deferment is an excellent management tool to utilize these annuals but still allow recovery of the perennial vegetation normally associated with this site.

Guide to initial stocking rates:
To determine a beginning carrying capacity on this site, use 50 percent of the preferred species, 35 percent of the desirable species and 5 percent of the undesirable species by weight can be counted as usable forage for the target animal(s) using the area. Use 900 pounds air-dry weight as the amount of forage required to support one animal unit month (AUM). From the available forage, calculate the number of acres needed to support each AU for the length of the planned grazing system.

Site Degradation:
If retrogression is induced by lack of fire in the ecosystem, the trees will increase at the expense of grass, forbs, and shrubs. When the trees become dominate on the site, soil erosion can be extreme (losing up to two feet of top soil).

If retrogression is induced by cattle, the grasses will decrease in relative proportions. Forbs, shrubs, and trees will increase in relative proportions. If retrogression continues, the site will be occupied by trees almost exclusively with either 5 or 10 percent of the total production in grass, forbs, and shrubs.

The following is from 1995 Range Site:

INTERPRETATIONS FOR WILDLIFE:
Practices or natural occurrences that set back succession such as fire, or clearing usually improve the area for mule deer and elk. Wildlife species that rely on large mature pinyon trees such as the white-breasted nuthatch and plains titmouse will be adversely affected by server retrogression. In general, most wildlife species are benefited by this site being in good to excellent condition.

Wildlife species list:
Coyote, cottontail, bushy tailed rat, golden eagle, pinyon jay, rock wren, Rocky Mountain elk, mountain lion, white-tailed jackrabbit, side blotched lizard, red-tailed hawk, western blue bird, hairy woodpecker, bobcat, rock squirrel, gopher snake, sagebrush lizard, chuckar, and plain titmouse.

Hydrological functions

Soils were originally assigned to hydrologic soil groups based on measured rainfall, runoff, and infiltrometer data (Musgrave 1955). Since the initial work was done to establish these groupings, assignment of soils to hydrologic soil groups has been based on the judgment of soil scientists. Assignments are made based on comparison of the characteristics of unclassified soil profiles with profiles of soils already placed into hydrologic soil groups. Most of the groupings are based on the premise that soils found within a climatic region that are similar in depth to a restrictive layer or water table, transmission rate of water, texture, structure, and degree of swelling when saturated, will have similar runoff responses. Four (4) Hydrologic Soil Groups are recognized (A-D). For specific definitions of each hydrologic soil group see the National Engineering Handbook, Chapter 7, Part 630 Hydrology, or visit:http://policy.nrcs.usda.gov/OpenNonWebContent.aspx? content=22526.wba The hydrologic soil groups are based on the following factors:

-intake and transmission of water under the conditions of maximum yearly wetness (thoroughly wet)
- soil not frozen
- bare soil surface
- maximum swelling of expansive clays

The slope of the soil surface is not considered when assigning hydrologic soil groups. In its simplest form, the hydrologic soil group is determined by the water transmitting soil layer with the lowest saturated hydraulic conductivity and depth to any layer that is more or less water impermeable (such as a fragipan or duripan) or depth to a water table (if present) (Caudle, et. al, 2013). The runoff curve numbers are determined by field investigations using hydrologic cover conditions and hydrologic soil groups.

Soils Hydrologic Group

Loamy – Arabrab D & C

Hydrologic soil groups are based on estimates of runoff potential. Soils are assigned to one of four groups according to the rate of water infiltration when the soils are not protected by vegetation, are thoroughly wet, and receive precipitation from long-duration storms (Soil Survey Staff, 2015).

The soils in the United States are assigned to four groups (A, B, C, and D) and three dual classes (A/D, B/D, and C/D). The groups are defined as follows:

Group A. Soils having a high infiltration rate (low runoff potential) when thoroughly wet. These consist mainly of deep, well drained to excessively drained sands or gravelly sands. These soils have a high rate of water transmission.

Group B. Soils having a moderate infiltration rate when thoroughly wet. These consist chiefly of moderately deep or deep, moderately well drained or well drained soils that have moderately fine texture to moderately coarse texture. These soils have a moderate rate of water transmission.

Group C. Soils having a slow infiltration rate when thoroughly wet. These consist chiefly of soils having a layer that impedes the downward movement of water or soils of moderately fine texture or fine texture. These soils have a slow rate of water transmission.

Group D. Soils having a very slow infiltration rate (high runoff potential) when thoroughly wet. These consist chiefly of clays that have a high shrink-swell potential, soils that have a high water table, soils that have a claypan or clay layer at or near the surface, and soils that are shallow over nearly impervious material. These soils have a very slow rate of water transmission (Soil Survey Staff, 2015).

Recreational uses

The following is from 1995 Range Site:

Areas of this site are used for hiking, camping, and picnics during the early and late part of the summer. It provides good wildlife cover especially during late fall and winter so it is commonly used by hunters.

Wood products

The following is from 1995 Range Site:

Wood products produced on this site are firewood, fence posts, and Christmas trees. Firewood can be harvested from the area in late succession stages to create an early or mild succession stage which produces better forage for grazing cattle. A patch cutting pattern for firewood can create better wildlife habitat by increasing the edge effect. An area in late successional stage can be managed for fence post production with light thinning. Christmas trees are best produced on areas in mid successional stages when the trees are relatively small and brushy.

Other information

The following is from 1995 Range Site:

ENGANGERED PLANTS AND ANIMALS:
Bald eagles can be found on this site during the winter season. Spineless hedgehog cactus can be found on this site.

OTHER INTERPRETATIONS:
Many areas of this site are dominated by the trees to the near exclusion of grasses, forbs, and shrubs. This has usually resulted in severe erosion. To reclaim and stabilize these sites, the trees must be controlled by fire, cutting, or chaining. Seeding may be required. Deferment from all grazing will also be required. Then to prevent the reinfestation of trees, a planned grazing system which rests each area once every three or four years is needed. Periodic fires will also prevent the trees from fully maturing and creating excessive competition.

Supporting information

Other references

Baisan, C. H. and T. W. Swetnam. 1990. Fire history on a desert mountain range: Rincon Mountain Wilderness, Arizona, USA. Canadian Journal of Forest Research. 20:1559-1569.

Betancourt, J. L., E. A. Pierson, K. A. Rylander, J. A. Fairchild-Parks, and J. S. Dean. 1993. Influence of history and climate on New Mexico pinyon-juniper woodlands. In: Gen. Tech. RM-236 - Managing Pinon-Juniper Ecosystems for Sustainability and Social Needs.

Cartledge, T. R., and J. G. Propper. 1993. Pinon-Juniper Ecosystems through Time: Information and Insights from the Past. In Gen. Tech. RM-236 - Managing Pinon-Juniper Ecosystems for Sustainability and Social Needs.

Chapman, S.S., G.E. Griffith, J.M. Omernik, A.B. Price, J. Freeouf, and D.L. Schrupp. 2006. Ecoregions of Colorado. (2 sided color poster with map, descriptive text, summary tables, and photographs). U.S. Geological Survey, Reston, VA. Scale 1:1,200,000.

Cleland, D.T.; Freeouf, J.A.; Keys, J.E.; Nowacki, G.J.; Carpenter, C.A.; and McNab, W.H. 2007. Ecological Subregions: Sections and Subsections for the conterminous United States. Gen. Tech. Report WO-76D [Map on CD-ROM] (A.M. Sloan, cartographer). Washington, DC: U.S. Department of Agriculture, Forest Service, presentation scale 1:3,500,000; colored.

Floyd, M.L., W.H. Romme, and D.D. Hanna. 2000. Fire History and vegetation pattern in Mesa Verde National Park, Colorado, USA. Ecological Applications. 10:1666-1680.

Floyd, M. L., D. D. Hanna, W. H. Romme. 2004. Historical and recent fire regimes in pinyon-juniper woodlands on Mesa Verde, Colorado, USA. Forest Ecology and Management. 198:269-289.

Kennard, D.K. and A.J. Moore. 2013. Fire history, woodland structure, and mortality in pinon-juniper woodland in the Colorado National Monument. Natural Areas Journal. 33:296-306.

Miller, R. F. and R. J. Tausch. 2001. The role of fire in juniper and pinyon woodlands: a descriptive analysis. In: Galley, K.E.M.; Wilson. T.P., [EDs]. Proceedings of the invasive species workshop: the role of fire in the control and spread on invasive species. Fire conference 2000. Tallahassee, Fl: Tall Timbers Research Station: Miscellaneous publication 11:15-30.

Miller, R. F. and J. A. Rose. 1999. Fire history and western juniper encroachment in sagebrush steppe. Journal of Range Management. 52:550-559.

Musgrave, G.W. 1955. How much of the rain enters the soil? In Water: U.S. Department of Agriculture Yearbook. Washington, D.C. P. 151- 159.

National Engineering Handbook. US Department of Agriculture, Natural Resources Conservation Service. Available: http://www.info.usda.gov/CED/Default.cfm#National%20Engineering%20Handbook Accessed February 25, 2008.

Natural Resources Conservation Service (NRCS). March 1995. Range Site Description for Mountain Pinyon #114: USDA, Denver Colorado.

Passey, H. B., W. K. Hugie, E. W. Williams, and D. E. Ball. 1982. Relationships between soil, plant community, and climate on rangelands of the Intermountain west. USDA, Soil Conservation Service, Tech. Bull. No. 1669.

Romme, W. H., C.D. Allen, J.D. Bailey, W.L. Baker, B.T. Bestelmeyer, P.M. Brown, K.S. Eisenhart, M.L. Floyd, D.W. Huffman, B.F. Jacobs, R.F. Miller, E.H. Muldavin, T.W. Swetnam, R.J. Tausch, and P.J. Weisberg. 2009. Historical and Modern Disturbance Regimes, Stand Structures, and Landscape Dynamics in Pinon-Juniper Vegetation of the Western United States. Rangeland Ecology and Management 62:203-222.

Shinneman, D. J. and W. L, Baker. 2009. Historical fir and multidecadal drought as context for pinon-juniper woodland restoration in western Colorado. Ecological Applications 19: 1231-1245.

Soil Survey Staff, Natural Resources Conservation Service, United States Department of Agriculture. Web Soil Survey. Available online at http://websoilsurvey.nrcs.usda.gov/. Accessed [5/3/2017].

Swetnam, T. and Baisan, C. 1996. Historical fire regime patterns in the southwestern United States since AD 1700. In: CD Allen (ed.) Fire Effects in Southwestern Forest: Proceedings of the 2nd La Mesa Fire Symposium, pp. 11-32. USDA Forest Service, Rocky Mountain Research Station, General Technical Report RM-GTR-286.

Tausch, R. J., N. E. West, and A. A. Nabi. 1981. Tree age and dominance patterns in Great Basin pinyon-juniper woodlands. Journal of Rangeland Management 34:259-264.

United States Department of Agriculture, Natural Resources Conservation Service. 2006. Land Resource Regions and Major Land Resource Areas of the United States, the Caribbean, and the Pacific Basin. U.S. Department of Agriculture Handbook 296.

Western Regional Climate Center. Retrieved from http://www.wrcc.dri.edu/summary/Climsmco.html on December 10, 2018

Zlatnik, E. 1999. Juniperus osteosperma. In: Fire Effects Information System. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). http://www.fs.fed.us/database/feis/. Accessed March 27, 2017.

Contributors

John Murray
Suzanne Mayne-Kinney

Approval

Kirt Walstad, 3/05/2024

Acknowledgments

Project Staff:

Suzanne Mayne-Kinney, Ecological Site Specialist, NRCS MLRA, Grand Junction SSO
Chuck Peacock, MLRA Soil Survey Leader, NRCS MLRA Grand Junction SSO

Program Support:

Rachel Murph, NRCS CO State Rangeland Management Specialist, Denver
Scott Woodhall, NRCS MLRA Ecological Site Specialist-QA Phoenix, AZ
Eva Muller, Regional Director, Rocky Mountain Regional Soil Survey Office, Bozeman, MT
B.J. Shoup, CO State Soil Scientist, Denver
Eugene Backhaus, CO State Resource Conservationist, Denver

Partners/Contributors:
Those involved in developing earlier versions of this site description include: Herman Garcia, retired CO State RMS and NRCS MLRA Ecological Site Specialist-QA Phoenix, AZ.

--Site Development and Testing Plan--:

Future work to validate and further refine the information in this Provisional Ecological Site Description is necessary. This will include field activities to collect low-, medium-, and high-intensity sampling, soil correlations, and analysis of that data.

Additional information and data is required to refine the Plant Production and Annual Production tables for this ecological site. The extent of MLRA 36 must be further investigated.

Field testing of the information contained in this Provisional ESD is required. As this ESD is moved to the Approved ESD level, reviews from the technical team, quality control, quality assurance, and peers will be conducted.

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)	Original written by J. Murray, C. Holcomb, L. Santana, F. Cummings, and S. Jaouen (1/18/2005). Revised and Updated by Suzanne Mayne-Kinney on 5/17/2017
Contact for lead author
Date	05/17/2017
Approved by	Kirt Walstad
Approval date
Composition (Indicators 10 and 12) based on	Annual Production

Indicators

Number and extent of rills:
Some rills are inherent to the site. Rills will frequently start the ends of water flow patterns or below exposed bedrock where the water can accumulate to cause erosion. The number of rills will depend on the slope. The higher the slope the greater the number of rills that will be associated with it.
Presence of water flow patterns:
Water flow patterns are expected. They frequently form around exposed bedrock where the water flows. Usually not enough water flows, they tend to be short and disconnected with debris dams. As slopes get steeper, flow paths are more frequent and evident, runoff is more rapid. Intense summer storms can cause water flow patterns to be more evident after storms.
Number and height of erosional pedestals or terracettes:
Short pedestals are expected at the base of the plants, there should not be exposed roots. When a large amount of well-developed biological crusts present, they can give the appearance of being pedestals. Terracettes and/or debris dams can form in the smaller water flow patterns.
Bare ground from Ecological Site Description or other studies (rock, litter, lichen, moss, plant canopy are not bare ground):
Expect 15-20% bare ground. Surface and sub-surface rock are inherent to this site.
Number of gullies and erosion associated with gullies:
A few gullies are found may be found on this site. The gullies start where enough water accumulates in the rills and where runoff of the rock outcrops is rapid. Gullies will be shallow (<20 inches) in depth due to the shallow nature of the soils found on this site. Erosion will expose more bedrock. Gullies will widen after bedrock is reached. Gullies may be 4 or more feet wide. The steep the slope the more potential, there is for gullies to form.
Extent of wind scoured, blowouts and/or depositional areas:
None. The trees on this site generally intercept the wind and prevent most wind generated soil erosion.
Amount of litter movement (describe size and distance expected to travel):
Litter for the most part stays in place. There can be some redistribution by water movement of the fine litter in the rills and water patterns. Most litter accumulates at the base of the plants on this site. Woody litter movement on this site is unusual. Litter movement is more evident on the steeper slopes and also, may be greater following intensive rainstorms.
Soil surface (top few mm) resistance to erosion (stability values are averages - most sites will show a range of values):
Stability class rating anticipated to be 3-6 in the interspaces at soil surface. Aggregate stability can be quite variable depending on soil texture, biological crusts and organic matter.
Soil surface structure and SOM content (include type of structure and A-horizon color and thickness):
SOM ranges from 0.5-3%. Surface soils are very shallow to shallow. Surface texture ranges from fine sandy loam to loam. Sometimes the soil surface can have gravels and cobbles in it. The A-horizon (soil surface) ranges from 0-7 inches in depth. It is typically described as weak fine and medium subangular blocky structure parting to weak fine and medium granular. The A horizon is expected to be more developed under the plant canopies. Use the specific information for the soil you are assessing in the published soil survey to supplement this description.
Effect of community phase composition (relative proportion of different functional groups) and spatial distribution on infiltration and runoff:
The presence of trees, perennial grasses and forbs, and shrubs will breakup raindrop impact and splash erosion. The spatial distribution of the plants, biological crusts and interspaces will provide small pockets for water storage and surface roughness that slows down runoff, allowing time for infiltration. The tree and shrub canopy is effective in intercepting rain drops and preventing splash erosion on the reference state. But, with increased tree canopy, understory canopy is reduced, increased bare soil and litter accumulates under trees, it can forms micro-topography that can help water accumulate which can cause more rapid runoff.
Presence and thickness of compaction layer (usually none; describe soil profile features which may be mistaken for compaction on this site):
A compaction layer is not expected, as this site has 20 inches or less of soil. However, soils with an abrupt horizon, strong subangular blocky structure, hard calcium carbonate layers and unweathered parent material may be mistaken for compaction layers.
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:
trees (Pinyon pine, Utah juniper,)>

Sub-dominant:
cool season bunchgrass (needle-and-thread, native bluegrasses, Indian ricegrass, prairie junegrass, bottlebrush squirreltail) = shrubs (Big sagebrush, black sagebrush, serviceberry, mountain mahogany, antelope bitterbrush, Gambel's oak) > forbs (buckwheat, locoweeds, cryptantha, Hood’s phlox, scarlet globemallow, skyrocket gilia, arrowleaf balsamroot, hairy goldaster, penstemons, asters, daisy, stemless goldenweed) >

Other:
cool season rhizomatous grass (Western wheatgrass)> cryptogams > sedges (Elk sedge)= warm season short bunchgrass (Blue grama)

Additional:
Amount of plant mortality and decadence (include which functional groups are expected to show mortality or decadence):
A mix of young, middle aged and old pinyon and Utah juniper are expected to be found on this site. In years with average or above average precipitation, shrubs, grasses and forbs should have little mortality or decadence. Tree mortality, especially pinyon, can be expected under severe and/or extended drought and subsequent insect infestations. Under a dense tree canopy, understory has increased decadence and mortality.
Average percent litter cover (%) and depth ( in):
15-30% litter cover at 0.25-2.0 inch depth, depending upon tree canopy. Most litter is at the base and under the canopy of the plants.
Expected annual annual-production (this is TOTAL above-ground annual-production, not just forage annual-production):
Tree canopy cover 0-15%: 800-1000 lbs./ac.; Tree canopy cover 15-30%: 500-800 lbs./ac.; Tree canopy cover > 30%: 100-500 lbs./ac. Production figures are for total annual vegetation.
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:
Cheatgrass, annual weeds, other noxious weeds.
Perennial plant reproductive capability:
All plants have the ability to reproduce in most years. Limitations are weather related, wildfire, natural disease, inter-species competition, and insects may temporarily reduce reproductive capability. Increased tree canopy will result in decreased understory reproductive capability.

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Natural ResourcesConservation Service

Ecological site F048AY448CO

Mountain Pinyon

Last updated: 3/05/2024 Accessed: 12/11/2024

General information

MLRA notes

Classification relationships

Ecological site concept

Associated sites

Similar sites

Table 1. Dominant plant species

Ecosystem states

State 1 submodel, plant communities

Natural Resources
Conservation Service

Last updated: 3/05/2024
Accessed: 12/11/2024