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Ecological site R069XY064CO

Gravel Breaks

Last updated: 9/07/2023
Accessed: 04/20/2024

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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.

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Figure 1. Mapped extent

Areas shown in blue indicate the maximum mapped extent of this ecological site. Other ecological sites likely occur within the highlighted areas. It is also possible for this ecological site to occur outside of highlighted areas if detailed soil survey has not been completed or recently updated.

MLRA notes

Major Land Resource Area (MLRA): 069X–Upper Arkansas Valley Rolling Plains

MLRA 69 is in the Arkansas Watershed of southeastern (SE) Colorado. It consists of rolling plains, river valleys, and canyonlands. The Arkansas River flows from the Rocky Mountains to Kansas. Tributaries include the Huerfano and Purgatoire Rivers. The MLRA is traversed by Interstate 25 and U.S. Highway 50, and includes the cities of Pueblo, La Junta, and Lamar. Other cities include Cañon City, and Walsenburg. Bent's Fort was once a major trading post along the Santa Fe Trail. The majority of land use is rangeland (greater than 75 percent), and 6 percent cropland. The remainder is urban, recreation, etc. Land ownership is mostly private. Federal lands include U.S. Forest Service Comanche National Grassland, Department of Defense Piñon Canyon Maneuver Site and Fort Carson. There is a minor amount of Bureau of Land Management and other federal land. State areas include Pueblo and John Martin reservoirs. Elevations MLRA-wide are 3,700 to 6,400 feet.

The "Dust Bowl" region (1930s) included SE Colorado, which is periodically affected by severe drought. Dust storms may form during drought years, in windy periods. Annual precipitation is 10 to 16 inches. Precipitation occurs mostly during the growing season, often during rapidly developing thunderstorms. Mean annual air temperature (MAAT) is 48 to 52 degrees Fahrenheit. Summer temperatures may exceed 100 degrees Fahrenheit. Evapotranspiration rates are high. Winter temperatures may be subzero. Snowfall varies from 20 to 40 inches per year. Blizzards can form quickly.

Classification relationships

MLRA 69 is in the Piedmont and Raton Sections of the Great Plains Province. The MLRA is further defined by Land Resource Units (LRUs) A, B, and C. The modal concepts of each LRU can be defined by soil properties and annual precipitation zones (PZ). Other features, such as climate, geology, landforms, and key vegetation, further refine these concepts and are described in the Ecological Site Description (ESD).

LRU A (10 to 12 inches PZ) is 2.4 million acres in the central portion of MLRA 69. There is irrigated cropland in the Arkansas Valley. Precipitation is too limited for dryland crops. Most of LRU A is rangeland, and includes the Comanche National Grassland (USFS). This LRU is in portions of Bent, Crowley, Otero, and Pueblo counties. Soil Moisture Regime is Ustic Aridic. The Mean Annual Air Temperature (MAAT) is 51 to 54 degrees Fahrenheit.

LRU B (12 to 14 inches PZ) is 4.7 million acres and includes portions of Baca, Bent, Crowley, El Paso, Fremont, Kiowa, Las Animas, Lincoln, Prowers, and Pueblo counties. Most of the LRU is in rangeland. Land uses include irrigated and dry cropland, small acreage and urban ownership. Land east of Interstate 25 remains largely agricultural. Canyonlands are in the southern half and include Piñon Canyon Maneuver Site and the Picket Wire Canyon of the Comanche National Grasslands. Soil moisture regime is Ustic Aridic. The mean annual air temperature is 50 to 54 degrees Fahrenheit.

The Gravel Breaks Ecological Site, LRUs A and B, was developed from an earlier version of the Gravel Breaks Ecological Site (2005, revised in 2007). This earlier version of the Gravel Breaks Ecological Site (2005) was based on input from Natural Resources Conservation Service (formerly Soil Conservation Service) and historical information obtained from the Gravel Breaks Range Site descriptions (1975, revised 1983). This ESD meets the Provisional requirements of the National Ecological Site Handbook (NESH). This ESD will continue refinement towards an Approved status according to the NESH.

Ecological site concept

The Gravel Breaks Ecological Site is a run-off site on slopes of greater than 10 percent. The soil depth is greater than 20 inches and it is influenced by rock fragments.

Associated sites

R069XY006CO	Loamy Plains This ecological site is commonly adjacent.
R069XY046CO	Shaly Plains This ecological site is commonly adjacent.
R069XY047CO	Alkaline Plains This ecological site is commonly adjacent.

R069XY006CO

Loamy Plains

This ecological site is commonly adjacent.

R069XY046CO

Shaly Plains

This ecological site is commonly adjacent.

R069XY047CO

Alkaline Plains

This ecological site is commonly adjacent.

Similar sites

R069XY058CO	Limestone Breaks This ecological site has a soil depth of less than 20 inches over limestone bedrock.
R069XY048CO	Shale Breaks This ecological site has a soil depth of less than 20 inches over shale bedrock.
R069XY080CO	Gypsum Breaks This ecological site has a soil depth of less than 20 inches over gypsum bedrock.
R069XY053CO	Sandstone Breaks This ecological site has a soil depth of less than 20 inches over sandstone bedrock.

Table 1. Dominant plant species

Tree	Not specified
Shrub	(1) Atriplex canescens (2) Krascheninnikovia lanata
Herbaceous	(1) Bouteloua curtipendula (2) Schizachyrium scoparium

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Physiographic features

This site occurs on plains or river valleys.

Table 2. Representative physiographic features

Landforms	(1) Hill (2) Ridge (3) Terrace (4) Fan remnant
Runoff class	Low to medium
Flooding frequency	None
Ponding frequency	None
Elevation	3,700 – 6,400 ft
Slope	2 – 40%
Ponding depth	Not specified
Water table depth	60 in
Aspect	Aspect is not a significant factor

Climatic features

Approximately 75 percent of the annual precipitation occurs during the growing season from mid-April to late September. Snowfall can vary greatly from year to year and can range from 20 to 40 inches per year. Winds are estimated to average 6 to 7 miles per hour annually. Daytime winds are generally stronger than nighttime winds. Occasional strong storms may bring brief periods of high winds with gusts to more than 60 miles per hour. The average length of the freeze-free period (28 °F) is 168 days. The average last freeze in the spring is April 22nd, and the average date of first freeze in fall is October 7th. The average length of the frost-free period (32 °F) is 149 days. The last frost in the spring is May 5th, and the average date for first frost in the fall (32 °F), is October 1. July is the hottest month, and January is the coldest. It is not uncommon for temperature to exceed 100 degrees Fahrenheit during the summer. Summer humidity is low and evaporation is high. The winters are characterized with frequent northerly winds, producing severe cold and temperatures dropping to -30 degrees Fahrenheit.

LRU A, in the Arkansas River Valley, is the hottest and driest portion of the MLRA. Mean Annual Precipitation (MAP) is 10 to 12 inches, and Mean Annual Air Temperature (MAAT) is 51 to 54 degrees Fahrenheit. LRU B is the largest extent. MAP is 12 to 14 inches, and MAAT is 50 to 54 degrees Fahrenheit.

Table 3. Representative climatic features

Frost-free period (characteristic range)	127-134 days
Freeze-free period (characteristic range)	149-161 days
Precipitation total (characteristic range)	12-14 in
Frost-free period (actual range)	121-135 days
Freeze-free period (actual range)	141-164 days
Precipitation total (actual range)	11-16 in
Frost-free period (average)	129 days
Freeze-free period (average)	153 days
Precipitation total (average)	13 in

Characteristic range

Actual range

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Figure 2. Monthly precipitation range

Characteristic range

Actual range

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Figure 3. Monthly minimum temperature range

Characteristic range

Actual range

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Figure 4. Monthly maximum temperature range

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Figure 5. Monthly average minimum and maximum temperature

Figure 6. Annual precipitation pattern

Figure 7. Annual average temperature pattern

Climate stations used

(1) EADS [USC00052446], Eads, CO
(2) PUEBLO RSVR [USC00056765], Pueblo, CO
(3) CHERAW 1 N [USC00051539], La Junta, CO
(4) ORDWAY 21 N [USC00056136], Ordway, CO
(5) ROCKY FORD 2 SE [USC00057167], Rocky Ford, CO
(6) PUEBLO MEM AP [USW00093058], Pueblo, CO
(7) LA JUNTA 20 S [USC00054726], La Junta, CO
(8) TACONY 13 SE [USC00058157], Boone, CO
(9) ORDWAY 2 ENE [USC00056131], Ordway, CO

Soil features

The soils of this site are very deep. They are somewhat excessively or excessively drained with moderate through very rapid permeability. The surface layer thickness ranges from 3 to 10 inches. The soil moisture regime is ustic aridic. The soil temperature regime is mesic. Parent material kind is old sandy and gravelly alluvium. Parent material originated from mixed sources.

Major soil series correlated to this ecological site include Cascajo, Chicosa, Karval, and Schamber.

Revisions to soil surveys are on-going. For the most recent updates, visit the Web Soil Survey, the official site for latest soils information: http://websoilsurvey.nrcs.usda.gov/app/WebSoilSurvey.aspx.

Surface Texture: loamy sand, sandy loam, loam, or sand with gravelly, very gravelly, or very cobbly modifiers

Table 4. Representative soil features

Parent material	(1) Alluvium
Surface texture	(1) Gravelly, very gravelly, very cobbly loamy sand (2) Gravelly, very gravelly, very cobbly sandy loam (3) Gravelly, very gravelly, very cobbly loam (4) Gravelly, very gravelly, very cobbly sand
Drainage class	Somewhat excessively drained to excessively drained
Permeability class	Moderate to very rapid
Soil depth	60 – 80 in
Surface fragment cover <=3"	5 – 60%
Surface fragment cover >3"	35%
Available water capacity (0-40in)	2 – 5.6 in
Calcium carbonate equivalent (0-40in)	40%
Electrical conductivity (0-40in)	4 mmhos/cm
Sodium adsorption ratio (0-40in)	4
Soil reaction (1:1 water) (0-40in)	6.6 – 8.4
Subsurface fragment volume <=3" (Depth not specified)	5 – 60%
Subsurface fragment volume >3" (Depth not specified)	35%

Ecological dynamics

The information in this ESD, including the state-and-transition model (STM), was developed using archeological and historical data, professional experience, and scientific studies. The information is representative of a complex set of plant communities. The plant composition has been determined by study of rangeland relic areas, areas protected from excessive disturbance, seasonal-use pastures, short-duration or time-controlled grazing strategies, and historical accounts.

Not all scenarios or plants are included. Key indicator plants, animals, and ecological processes are described to inform land management decisions.

This region was historically occupied by large grazing animals, such as bison, along with pronghorn and mule deer. Deer and pronghorn are widely distributed throughout the MLRA. This is an important site for livestock grazing, especially cattle.

Drought has historically impacted the vegetation of this region. Changes in species composition vary depending upon the duration and severity of the drought cycle and prior grazing management. Recent drought events have increased mortality of blue grama significantly in some locales, along with other bunchgrasses, such as sand bluestem, little bluestem, needle and thread, Fendler threeawn, and squirreltail. Historic fire frequency (pre-industrial) is estimated at 15 to 20 years (Guyette, 2012), randomly distributed, and started by lightning at various times throughout the growing season. Early human inhabitants were also likely to start fires (deliberate or accidental).

The site is dominated by warm-season mid bunchgrass (sideoats grama, little bluestem). Secondary grasses are warm-season short bunchgrass (blue grama) and warm-season mid rhizomatous grass (galleta). Minor grasses include cool-season mid bunchgrass (needle and thread), warm-season tall bunchgrasses (big bluestem, switchgrass), warm-season tall rhizomatous grass (prairie sandreed) and cool-season mid rhizomatous grass (wheatgrass). Other minor grasses and grass-like plants that occur is small amounts are hairy grama, Indian ricegrass, sand dropseed, and sun sedge. Various shrubs (fourwing saltbush, skunkbush sumac, winterfat), and forbs (dotted gayfeather, purple prairieclover, scarlet globemallow) occur on the site.

Recurring season herbivory without adequate recovery periods causes this site to degrade. Grasses such as sideoats grama, little bluestem, big bluestem, prairie sandreed, switchgrass, western wheatgrass, and needle and thread decrease in both frequency and production. Blue grama and hairy grama increase. Forbs and shrubs such as purple prairie clover, dotted gayfeather, fourwing saltbush, and winterfat decrease. With continuous grazing mid- and tallgrasses can eventually be removed from the plant community as blue and hairy grama become dominant. Over the long-term, continuous use or long term non-use and lack of fire will result in large amounts of bare ground. Species such as red threeawn, ring muhly, sand dropseed, mat loco, sessile nailwort, small soapweed, broom snakeweed, and annuals increase or invade the site.

Drier and warmer climatic conditions exist in the central portion of MLRA 69. This area includes the eastern half of Pueblo county, northern Otero, extreme northwestern Bent, western edge of Kiowa, southern edge of Lincoln and all of Crowley County. These conditions are primarily caused by a rain shadow effect from the southern Rocky Mountains. Evapotranspiration rates (atmospheric demand) are higher in this area of MLRA 69. Total annual production is typically lower.

Southeastern Colorado was strongly affected by extended drought conditions in the “Dust Bowl” period of the 1930s, with recurrent drought cycles in the 1950s and 1970s. Extreme to exceptional drought conditions have re-visited the area from 2002 to 2012, with brief interludes of near normal to normal precipitation years. “During periods of drought, high winds give rise to the dust storms which are especially characteristic of the southeastern plains (WRCC, 2022).” Recent drought events have increased mortality of blue grama upwards of 80 percent in some locales. The long-term effects of these latest drought years have yet to be determined.

Growth of native cool-season plants begins about April 15 and continues to mid-June. Native warm-season plants begin growth about May 1 and continue to about August 15. Regrowth of cool-season plants occurs in September and October in most years, depending on moisture. For detailed information, visit the Western Regional Climate Center website at https://wrcc.dri.edu/.

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

2. Blue Grama Dominant State

3. Bare Ground State

T1A	-	Heavy, continuous grazing. Lack of fire.
T1B	-	Heavy, long-term grazing. Non-use. No fire.
R2A	-	Prescribed grazing. Prescribed fire.
T2A	-	Heavy, continuous grazing. Lack of fire.

State 1 submodel, plant communities

1.1. Bouteloua curtipendula-Schizachyrium scoparium (sideoats grama-little bluestem).

1.2. Bouteloua gracilis (blue grama) Community.

1.1A	-	Heavy, season-long grazing. Lack of fire.
1.2A	-	Prescribed grazing. Prescribed fire.

State 2 submodel, plant communities

2.1. Bouteloua gracilis (blue grama) Dominant Community.

State 3 submodel, plant communities

3.1. Bromus tectorum-Phlox hoodii (cheatgrass-spiny flox) Bare Ground, Cryptogams, Community.

State 1
Reference State

The Reference State is characterized by two plant community phases that represent the natural range of variability and disturbance regimes within the site. These plant community phases are maintained by a historic fire frequency estimated to be on 15 to 20 year intervals, and herbivory by large ungulates with adequate recovery periods.

Dominant plant species

fourwing saltbush (Atriplex canescens), shrub
winterfat (Krascheninnikovia lanata), shrub
sideoats grama (Bouteloua curtipendula), grass
blue grama (Bouteloua gracilis), grass

Community 1.1
Bouteloua curtipendula-Schizachyrium scoparium (sideoats grama-little bluestem).

This plant community is the interpretive plant community for this site and is considered to be the reference plant community. This community evolved with grazing by large herbivores and is suited to grazing by domestic livestock. Historically, fires likely occurred infrequently. This plant community can be found on areas that are grazed and where the grazed plants receive adequate recovery periods during the growing season. The potential vegetation is about 75 to 85 percent grasses and grass-likes, 10 to 15 percent forbs and 5 to 10 percent woody plants. The principal mid-grasses are little bluestem and sideoats grama. Secondary grasses include blue grama, galleta, big bluestem, prairie sandreed, switchgrass, needle and thread, hairy grama, and western wheatgrass. Threadleaf and sun sedge are common. Dominant forbs are purple prairie clover, dotted gayfeather, and upright prairie coneflower. Winterfat, Bigelow sagebrush, and skunkbush sumac are some of the major shrubs found on this plant community. This is a sustainable plant community in terms of soil stability, watershed function, and biological integrity. Litter is properly distributed where vegetative cover is continuous. Some litter movement may occur on steeper slopes. Decadence and natural plant mortality is very low. Community dynamics, nutrient cycle, water cycle, and energy flow are functioning properly. This community is resistant to many disturbances with the exceptions of heavy, continuous grazing, tillage, and development into urban or other uses. Areas having lost all vegetation, such as livestock and vehicle trails are subject to high erosion rates and extreme runoff. Total annual production, during an average year, ranges from 350 to 1200 pounds of air-dry weight and averages 750 pounds.

Dominant plant species

fourwing saltbush (Atriplex canescens), shrub
winterfat (Krascheninnikovia lanata), shrub
sideoats grama (Bouteloua curtipendula), grass
little bluestem (Schizachyrium scoparium), grass

Figure 8. 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	245	600	1005
Forb	70	94	115
Shrub/Vine	35	56	80
Total	350	750	1200

Figure 9. Plant community growth curve (percent production by month). CO6905, Warm-season dominant, cool-season sub-dominant; MLRA-69; upland coarse-textured soils.

Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
J	F	M	A	M	J	J	A	S	O	N	D
0	0	5	10	22	35	15	10	3	0	0	0

Community 1.2
Bouteloua gracilis (blue grama) Community.

The dominant grass is blue grama. Little bluestem and sideoats grama are still present as secondary grasses in the community. Big bluestem, Indiangrass, switchgrass, prairie sandreed, needle and thread, western wheatgrass, purple prairie clover, and winterfat have been reduced. Hairy grama, sand dropseed, Fendler's threeawn, Hoods phlox, hairy goldaster, Cuman ragweed, and slimflower scurfpea have increased. Woody plants include fourwing saltbush, skunkbush sumac, winterfat, and small soapweed. Plant frequency and vigor have decreased. Reduction of tall, mid- and rhizomatous grasses, nitrogen-fixing forbs, the shrub component, and increased warm-season shortgrass has begun to alter the biotic integrity of this community. Water and nutrient cycles are becoming impaired. Litter levels have been reduced. Flow paths and rills are more apparent on steeper slopes. Pedestalled plants are common. Total annual production, during an average year, ranges from 200 to 700 pounds of air-dry weight and averages 400 pounds.

Dominant plant species

fourwing saltbush (Atriplex canescens), shrub
skunkbush sumac (Rhus trilobata), shrub
blue grama (Bouteloua gracilis), grass

Figure 10. Plant community growth curve (percent production by month). CO6905, Warm-season dominant, cool-season sub-dominant; MLRA-69; upland coarse-textured soils.

Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
J	F	M	A	M	J	J	A	S	O	N	D
0	0	5	10	22	35	15	10	3	0	0	0

Pathway 1.1A
Community 1.1 to 1.2

Heavy, season-long grazing without adequate recovery periods between grazing events and reduced fire frequency shifts this plant community to the 1.2 community.

Pathway 1.2A
Community 1.2 to 1.1

Herbivory with adequate recovery periods and prescribed fire move this plant community to the reference plant community.

Conservation practices

Prescribed Burning
Prescribed Grazing

State 2
Blue Grama Dominant State

The Blue Grama Dominant State is represented by one plant community phase. Species diversity and production have been severely reduced. Litter levels are very low. Mineral and water cycles are impaired due to the loss of deeper-rooted grasses, forbs, and shrubs. Rills are evident and soil loss is obvious, especially on steeper slopes. Pedestalled plants with exposed roots are common. The loss of dominant and subdominant structural/functional groups reduces the biodiversity and productivity.

Dominant plant species

broom snakeweed (Gutierrezia sarothrae), shrub
soapweed yucca (Yucca glauca), shrub
Bigelow sage (Artemisia bigelovii), shrub
blue grama (Bouteloua gracilis), grass

Community 2.1
Bouteloua gracilis (blue grama) Dominant Community.

Blue grama dominates the community and exhibits a mosaic sod-bound appearance. Tallgrasses have been removed. Little bluestem and sideoats grama may remain in remnant amounts on steeper slopes. Forbs and shrubs that have increased are wormwood, Cuman ragweed, rush skeletonplant, hairy goldaster, Bigelow sagebrush, small soapweed, and broom snakeweed. Cushion plants such as mat loco, Hood’s phlox, and sessile nailwort have increased. Production ranges from 100 to 350 pounds of air-dry vegetation per acre per year and averages 200 pounds.

Dominant plant species

Bigelow sage (Artemisia bigelovii), shrub
broom snakeweed (Gutierrezia sarothrae), shrub
soapweed yucca (Yucca glauca), shrub
blue grama (Bouteloua gracilis), grass

Figure 11. Plant community growth curve (percent production by month). CO6907, Warm-season dominant; MLRA-69; upland coarse-textured soils.

Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
J	F	M	A	M	J	J	A	S	O	N	D
0	0	0	5	30	40	20	5	0	0	0	0

State 3
Bare Ground State

This state has one community. It is characterized by an impairment of all ecological functions. Bare ground, cushion plants, and cryptogamic crusts have significantly increased. Water erosion can be severe on steeper slopes as evidenced by pedestaled plants and connected water flow paths.

Dominant plant species

broom snakeweed (Gutierrezia sarothrae), shrub
soapweed yucca (Yucca glauca), shrub
plains pricklypear (Opuntia polyacantha), shrub
cheatgrass (Bromus tectorum), grass
Fendler threeawn (Aristida purpurea var. longiseta), grass
spiny phlox (Phlox hoodii), other herbaceous
creeping nailwort (Paronychia sessiliflora), other herbaceous
burningbush (Bassia scoparia), other herbaceous

Community 3.1
Bromus tectorum-Phlox hoodii (cheatgrass-spiny flox) Bare Ground, Cryptogams, Community.

Bare ground, cushion plants, and cryptogamic crusts have significantly increased. Remnant amounts of blue and hairy grama may still be found. In the case of long term non-use or no fire plant decadence increases. Other plants that may be present are Russian thistle, burningbush, Fendler's threeawn, cheatgrass, cushion plants (mat loco, creeping nailwort, Hood's phlox), and small soapweed. Water erosion can be severe on steeper slopes as evidenced by pedestaled plants and connected water flow paths. Total annual production can vary from 25 to 150 pounds of air-dry vegetation per acre per year.

Dominant plant species

broom snakeweed (Gutierrezia sarothrae), shrub
soapweed yucca (Yucca glauca), shrub
plains pricklypear (Opuntia polyacantha), shrub
cheatgrass (Bromus tectorum), grass
Fendler threeawn (Aristida purpurea var. longiseta), grass
spiny phlox (Phlox hoodii), other herbaceous
creeping nailwort (Paronychia sessiliflora), other herbaceous
Russian thistle (Salsola), other herbaceous
burningbush (Bassia scoparia), other herbaceous

Figure 12. Plant community growth curve (percent production by month). CO6905, Warm-season dominant, cool-season sub-dominant; MLRA-69; upland coarse-textured soils.

Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
J	F	M	A	M	J	J	A	S	O	N	D
0	0	5	10	22	35	15	10	3	0	0	0

Transition T1A
State 1 to 2

Heavy, continuous grazing without adequate recovery periods and lack of fire shifts this state across an ecological threshold to the Blue Grama Dominant State.

Transition T1B
State 1 to 3

Heavy, continuous grazing, lack of fire, and long-term non-use move this state to the Bare Ground State. This transition may take 40 years or more.

Restoration pathway R2A
State 2 to 1

Long-term prescribed grazing with adequate recovery opportunity between grazing events and prescribed fire move this plant community to the Reference State. This transition may take upwards of 40 years or more to achieve.

Conservation practices

Prescribed Burning
Prescribed Grazing

Transition T2A
State 2 to 3

Heavy, continuous grazing without adequate recovery periods and lack of fire shift this state across an ecological threshold to the Bare Ground State.

Additional community tables

Table 6. Community 1.1 plant community composition

Group	Common name	Symbol	Scientific name	Annual production (lb/acre)	Foliar cover (%)
Grass/Grasslike
1				560–640
	sideoats grama	BOCU	Bouteloua curtipendula	225–265	–
	little bluestem	SCSC	Schizachyrium scoparium	75–150	–
	blue grama	BOGR2	Bouteloua gracilis	40–115	–
	big bluestem	ANGE	Andropogon gerardii	10–40	–
	prairie sandreed	CALO	Calamovilfa longifolia	10–40	–
	needle and thread	HECOC8	Hesperostipa comata ssp. comata	10–40	–
	James' galleta	PLJA	Pleuraphis jamesii	15–40	–
	western wheatgrass	PASM	Pascopyrum smithii	10–25	–
	switchgrass	PAVI2	Panicum virgatum	10–25	–
	hairy grama	BOHI2	Bouteloua hirsuta	10–25	–
	Grass, perennial	2GP	Grass, perennial	10–20	–
	sun sedge	CAINH2	Carex inops ssp. heliophila	10–20	–
	New Mexico feathergrass	HENE5	Hesperostipa neomexicana	0–20	–
	Indian ricegrass	ACHY	Achnatherum hymenoides	10–15	–
	threadleaf sedge	CAFI	Carex filifolia	10–15	–
	Indiangrass	SONU2	Sorghastrum nutans	0–15	–
	sand dropseed	SPCR	Sporobolus cryptandrus	10–15	–
	buffalograss	BODA2	Bouteloua dactyloides	0–10	–
	Fendler threeawn	ARPUL	Aristida purpurea var. longiseta	0–10	–
	ring muhly	MUTO2	Muhlenbergia torreyi	0–10	–
	squirreltail	ELELE	Elymus elymoides ssp. elymoides	0–10	–
	hairy woollygrass	ERPI5	Erioneuron pilosum	0–10	–
Forb
2				75–115
	Forb, perennial	2FP	Forb, perennial	10–20	–
	purple prairie clover	DAPU5	Dalea purpurea	10–15	–
	dotted blazing star	LIPU	Liatris punctata	10–15	–
	rush skeletonplant	LYJU	Lygodesmia juncea	0–5	–
	lacy tansyaster	MAPIP4	Machaeranthera pinnatifida ssp. pinnatifida var. pinnatifida	0–5	–
	white locoweed	OXSE	Oxytropis sericea	0–5	–
	New Mexico groundsel	PANEM	Packera neomexicana var. mutabilis	0–5	–
	creeping nailwort	PASE	Paronychia sessiliflora	0–5	–
	beardtongue	PENST	Penstemon	0–5	–
	spiny phlox	PHHO	Phlox hoodii	0–5	–
	upright prairie coneflower	RACO3	Ratibida columnifera	0–5	–
	threadleaf ragwort	SEFLF	Senecio flaccidus var. flaccidus	0–5	–
	scarlet globemallow	SPCO	Sphaeralcea coccinea	0–5	–
	white heath aster	SYER	Symphyotrichum ericoides	0–5	–
	stiff greenthread	THFI	Thelesperma filifolium	0–5	–
	sulphur-flower buckwheat	ERUM	Eriogonum umbellatum	0–5	–
	shaggy dwarf morning-glory	EVNU	Evolvulus nuttallianus	0–5	–
	hairy false goldenaster	HEVI4	Heterotheca villosa	0–5	–
	tarragon	ARDR4	Artemisia dracunculus	0–5	–
	twogrooved milkvetch	ASBI2	Astragalus bisulcatus	0–5	–
	spiny milkvetch	ASKE	Astragalus kentrophyta	0–5	–
	woolly locoweed	ASMO7	Astragalus mollissimus	0–5	–
Shrub/Vine
3				40–75
	Shrub (>.5m)	2SHRUB	Shrub (>.5m)	10–20	–
	fourwing saltbush	ATCA2	Atriplex canescens	10–20	–
	skunkbush sumac	RHTR	Rhus trilobata	0–20	–
	winterfat	KRLA2	Krascheninnikovia lanata	10–15	–
	Bigelow sage	ARBI3	Artemisia bigelovii	0–15	–
	prairie sagewort	ARFR4	Artemisia frigida	0–10	–
	shadscale saltbush	ATCO	Atriplex confertifolia	0–10	–
	tree cholla	CYIMI	Cylindropuntia imbricata var. imbricata	0–10	–
	spreading buckwheat	EREF	Eriogonum effusum	0–10	–
	rubber rabbitbrush	ERNAG	Ericameria nauseosa ssp. nauseosa var. glabrata	0–10	–
	broom snakeweed	GUSA2	Gutierrezia sarothrae	0–10	–
	plains pricklypear	OPPO	Opuntia polyacantha	0–10	–
	golden currant	RIAU	Ribes aureum	0–10	–
	soapweed yucca	YUGL	Yucca glauca	0–10	–

Interpretations

Animal community

WILDLIFE INTERPRETATIONS:
The variety of grasses, forbs, and shrubs on this ecological site in the various plant communities provides habitat for a wide range of wildlife species. Historic large grazers that influenced these plant communities were bison, elk, and pronghorn. Changes over time have resulted in the loss of bison, the reduction in elk numbers, and pronghorn population swings. Domestic grazers now share these habitats with wildlife. The grassland communities of eastern Colorado are home to many bird species. Changes in the composition of the plant community when moving from the reference plant community to other communities on this ecological site may result in dramatic species shifts in the bird community. Because of a lack of permanent water, fish and many amphibians are not expected on this ecological site. Mule and white-tailed deer may use this ecological site, however the shrub cover is too low to expect more than occasional use. The gray wolf and wild bison used this ecological site in historic times. The wolf is thought to be extirpated from Eastern Colorado. Bison in the area are domesticated.

Reference Plant Community:
The grasses, forbs, and shrubs in this plant community provide habitat for many reptiles including western rattlesnake, bullsnake, and racer. If water is available for breeding, spadefoot toads and tiger salamanders may be found here. The structural diversity in the plant community on this site provides habitat for Cassin’s and Brewer’s sparrow and lark bunting. Ferruginous and Swainson’s hawks are commonly seen on this site. Small mammals such as white-tailed jackrabbit, badger, swift fox, plains pocket gopher, and several species of mice are common. Pronghorn is a typical ungulate\.

1.2 Community:
All wildlife found in the reference plant community are expected. The loss of some vegetative structural diversity makes it less attractive to many species.

2.2, 3.1 Communities:
The loss of shrubs and mid-tall grasses creates habitat for typical shortgrass species such as black-tailed prairie dog, burrowing owl, mountain plover, and horned lark. Black-tailed jackrabbit may replace white-tailed jackrabbit in these communities. Reptiles using these communities are short-horned lizard and lesser earless lizard.

GRAZING INTERPRETATIONS:
The following table lists suggested initial stocking rates for an animal unit (1000 pound beef cow) under continuous grazing (yearlong grazing or growing-season-long grazing) based on normal growing conditions. However, continuous grazing is not recommended. These estimates should only be used as preliminary guidelines in the initial stages of the conservation planning process. Often, the existing plant composition does not entirely match any particular plant community described in this ecological site description. Therefore, field inventories are always recommended to document plant composition, total production, and palatable forage production. Carrying capacity estimates that reflect on-site conditions should be calculated using field inventories.

If the following production estimates are used, they should be adjusted based on animal kind or class and on the specific palatability of the forage plants in the various plant community descriptions. Under a properly stocked, properly applied, prescribed grazing management system that provides adequate recovery periods following each grazing event, improved harvest efficiencies eventually result in increased carrying capacity. See USDA-NRCS Colorado Prescribed Grazing Standard and Specification Guide (528).

The stocking rate calculations are based on the total annual forage production in a normal year multiplied by 25 percent harvest efficiency divided by 912.5 pounds of ingested air-dry vegetation for an animal unit per month (AUM).

Plant Community Production (lbs./acre) and Stocking Rate (AUM/acre)

Reference Plant Community - (750) (0.21)

1.2 Community - (400) (0.11)

2.1 Community - (200) (0.05)

These stocking rates are guidelines and specific grazing plans require an on-site visit.

Grazing by domestic livestock is one of the major income-producing industries in the area. Rangelands in this area provide yearlong forage under prescribed grazing for cattle, sheep, horses and other herbivores.

Hydrological functions

Water is the principal factor limiting forage production on this site. Soils in hydrologic group A and B dominate this site. Infiltration varies from moderate to high and runoff potential for this site varies from moderate to low depending on soil hydrologic group and ground cover. Areas where ground cover is less than 50 percent have the greatest potential to have reduced infiltration and higher runoff (refer to NRCS Section 4, National Engineering Handbook (USDA–NRCS, 1972–2012) for runoff quantities and hydrologic curves).

Recreational uses

This site provides hunting, hiking, photography, bird watching, and other opportunities. The wide varieties of plants that bloom from spring until fall have an aesthetic value that appeals to visitors.

Wood products

No appreciable wood products are present on the site.

Other products

This site is a source for gravel and is extensively mined in areas.

Site Development and Testing Plan:

General Data (MLRA and Revision Notes, Hierarchical Classification, Ecological Site Concept, Physiographic, Climate, and Water Features, and Soils Data):

Updated, All “Required” items complete to Provisional level

Need to run slope analysis to refine modal concept.

Community Phase Data (Ecological Dynamics, STM, Transition and Recovery Pathways, Reference Plant Community, Species Composition List, Annual Production Table):

Updated. All “Required” items complete to Provisional level.

NOTE: Annual Production Table and Species Composition List are from the “Previously Approved ESD. These will need review for future updates at the next “Approved” level.

Each Alternative State/Community:

Complete to Provisional level. Narrative for each state/community has been updated.

The “Bare Ground” State can be arrived at by two pathways; By long term continuous grazing (from State 2), or by long term non-use, no fire (from State 1). A decadent plant community can occur with weedy species, and annuals coming into the site. This current concept needs further investigation and analysis.

Supporting Information (Site Interpretations, Associated and Similar Sites, Inventory Data References, Agency/State Correlation, References):

Updated. All “Required” items complete to Provisional level.

Animal Community
Wildlife interpretations, general narrative, updated. Interpretations for
individual plant community states/phases, pending. Pending PK updates…

Livestock Interpretations updated to reflect the Plant Community name revisions. The stocking rate calculations remain the same since they are based on the “Previously Approved” Total Annual Production table.

The stocking rate calculations will be updated when Total Annual Production and Plant
Community annual production is revised at the next “Approved” level.

Hydrology:
From “Previously Approved” ESD (2004). Will be updated at next “approved” level.

Other Site Interpretations:
Recreational Uses, Wood Products, Other Products, and Plant Preferences table, carried over from “Previously Approved” ESD (2004).

Supporting Information:

Updated. All “Required” items complete to Provisional level.

Rangeland Health Reference Sheet:

From “Previously Approved” ESD (2004). Will be updated at the next “Approved” level.

Note: There is only a very minor extent of Gravel Breaks mapped in LRU C.

“Future work, as described in a project plan, to validate the information in this provisional ecological site description is needed. This will include field activities to collect low and medium intensity sampling, soil correlations, and analysis of that data. Annual field reviews should be done by soil scientists and vegetation specialists. A final field review, peer review, quality control, and quality assurance reviews of the ESD will be needed to produce the final document.” (NI 430_306 ESI and ESD, April, 2015)

Other information

Relationship to Other Classifications:
NRCS Classification Hierarchy:
Physiographic Divisions of the United States (Fenneman, 1946): Physiographic DivisionPhysiographic ProvincePhysiographic SectionLand Resource RegionMajor Land Resource Area (MLRA)Land Resource Unit (LRU).

USFS Classification Hierarchy:
National Hierarchical Framework of Ecological Units (Cleland et al, 181-200):
DomainDivisionProvinceSectionSubsectionLandtype Association LandtypeLandtype Phase.

Supporting information

Inventory data references

NRI: references to Natural Resource Inventory data
Information presented here has been derived from data collection on private and federal lands using:
• Double Sampling (clipped 2 of 5 plots)*
• Rangeland Health (Pellant et al., 2005)
• Soil Stability (Pellant et al., 2005)
• Line Point Intercept : Foliar canopy, basal cover (Forb, Graminoid, Shrub, subshrub, Lichen, Moss, Rock fragments, bare ground, % Litter) (Herrick et al., 2005)
• Soil pedon descriptions collected on site (Schoeneberger et al., 2012)

*NRCS double-sampling method, CO NRCS Similarity Index Worksheet 528(1).
Additional reconnaissance data collection using numerous ocular estimates and other inventory data; NRCS clipping data for USDA program support; Field observations from experienced range trained personnel. Specific data information is contained in individual landowner/user case files and other files located in county NRCS field offices.

References

Guyette, R.P., M.C. Stambaugh, D.C. Dey, and R. Muzika. 2012. Predicting Fire Frequency with Chemistry and Climate. Ecosystems 15:322–335.

Other references

Data collection for this ecological site was done in conjunction with the progressive soil surveys within the Upper Arkansas Valley (MLRA 69) of Colorado. The site has been mapped and correlated with soils in the following soil surveys: Baca County, Bent County, Crowley County, El Paso County Area, Fremont County Area, Huerfano County Area, Kiowa County, Las Animas County: Parts of Huerfano and Las Animas, Lincoln County, Otero County, Prowers County, and Pueblo Area: Parts of Pueblo and Custer Counties.

30 Year Climatic and Hydrologic Normals (1981-2010) Reports. National Water and climate Center: Portland, OR. August 2015

ACIS-USDA Field Office Climate Data (WETS), period of record 1971-2000 http://agacis.rcc-acis.org (powered by WRCC) Accessed March 2016

Andrews, R. and R. Righter. 1992. Colorado Birds. Denver Museum of Natural History, Denver, CO. 442

Armstrong, D.M. 1972. Distribution of mammals in Colorado. Univ. Kansas Museum Natural History Monograph #3. 415.

Butler, LD., J.B. Cropper, R.H. Johnson, A.J. Norman, G.L. Peacock, P.L. Shaver, and K.E. Spaeth. 1997, revised 2003. National Range and Pasture Handbook. National Cartography and Geospatial Center’s Technical Publishing Team: Fort Worth, TX. http://www.glti.nrcs.usda.gov/technical/publications/nrph.html Accessed August 2015

Clark, J., E. Grimm, J. Donovan, S. Fritz, D. Engrstom, and J. Almendinger. 2002. Drought cycles and landscape responses to past Aridity on prairies of the Northern Great Plains, USA. Ecology, 83(3), 595-601.

Cleland, D., P. Avers, W.H. McNab, M. Jensen, R. Bailey, T. King, and W. Russell. 1997. National Hierarchical Framework of Ecological Units, published in Ecosystem Management: Applications for Sustainable Forest and Wildlife Resources, Yale University Press

Cooperative climatological data summaries. NOAA. Western Regional Climate Center: Reno, NV. Web. http://www.wrcc.dri.edu/climatedata/climsum Accessed August 2015

Egan, Timothy. 2006. The Worst Hard Time. Houghton Mifflin Harcourt Publishing Company: New York, NY.

Fitzgerald, J.P., C.A. Meaney, and D.M. Armstrong. 1994. Mammals of Colorado. Denver Museum of Natural History, Denver, CO. 467. Hammerson, G.A. 1986. Amphibians and reptiles in Colorado. CO Div. Wild. Publication Code DOW-M-I-3-86. 131.

Herrick, Jeffrey E., J.W. Van Zee, K.M. Haystad, L.M. Burkett, and W.G. Witford. 2005. Monitoring Manual for Grassland, Shrubland, and Savanna Ecosystems, Volume II. U.S. Dept. of Agriculture, Agricultural Research Service. Jornada Experimental Range, Las Cruces, N.M.

Kingery, H., Ed. (1998) Colorado Breeding Birds Atlas. Dist. CO Wildlife Heritage Foundation: Denver, CO. 636.

National Water & Climate Center. USDA-NRCS. USDA Pacific Northwest Climate Hub: Portland, OR. http://www.wcc.nrcs.usda.gov/ Accessed March 2016

National Weather Service Co-op Program. 2010. Colorado Climate Center. Colorado State Univ. Web. http://climate.atmos.colostate.edu/dataaccess.php March 2016

Pellant, M., P. Shaver, D.A. Pyke, J.E. Herrick. (2005) Interpreting Indicators of Rangeland Health, Version 4. BLM National Business Center Printed Materials Distribution Service: Denver, CO.

PLANTS Database. 2015. USDA-NRCS. Web. http://plants.usda.gov/java/ Accessed August 2015. February 2016

PRISM Climate Data. 2015. Prism Climate Group. Oregon State Univ. Corvallis, OR. http://www.prism.oregonstate.edu/ Accessed August 2015.

Rennicke, J. 1990. Colorado Wildlife. Falcon Press, Helena and Billings, MT and CO Div. Wildlife, Denver CO. 138.

Schoeneberger, P.J., D.A. Wysockie, E.C. Benham, and Soil Survey Staff. 2012. Field book for describing and sampling soils, Version 3.0. Natural Resources Conservation Service, National Soil Survey Center: Lincoln, NE.

The Denver Posse of Westerners. 1999. The Cherokee Trail: Bent’s Old Fort to Fort Bridger. The Denver Posse of Westerners, Inc. Johnson Printing: Boulder, CO

U.S. Dept. of Agriculture, Agricultural Research Service. September, 1991. Changes in Vegetation and Land Use I eastern Colorado, A Photographic study, 1904-1986.

U.S. Dept. 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. US Department of Agriculture Handbook 296.

U.S. Dept. of Agriculture, Natural Resources Conservation Service. National Geospatial Center of Excellence. Colorado annual Precipitation Map from 1981-2010, Annual Average Precipitation by State

U.S. Dept. of Agriculture, Natural Resources Conservation Service. 2009. Part 630, Hydrology, National Engineering Handbook

U.S. Dept. of Agriculture, Natural Resources Conservation Service. 1972-2012. National Engineering Handbook Hydrology Chapters. http://www.nrcs.usda.gov/wps/portal/nrcs/detailfull/national/water/?&cid=stelprdb1043063 Accessed August 2015.

U.S. Dept. of Agriculture, Natural Resources Conservation Service. National Soil Survey Handbook title 430-VI. http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/ref/?cid=nrcs142p2_054242 Accessed July 2015

U.S. Dept. of Agriculture, Soil Survey Division Staff. 1993. Soil Survey Manual.

U.S. Dept. of Agriculture.1973. Soil Survey of Baca County, Colorado.

U.S. Dept. of Agriculture. 1970. Soil Survey of Bent County, Colorado.

U.S. Dept. of Agriculture. 1968. Soil Survey of Crowley County, Colorado.

U.S. Dept. of Agriculture. 1981 Soil Survey of El Paso County Area, Colorado.

U.S. Dept. of Agriculture. 1995. Soil Survey of Fremont County Area, Colorado.

U.S. Dept. of Agriculture. 1983. Soil Survey of Huerfano County Area, Colorado.

U.S. Dept. of Agriculture.1981. Soil Survey of Kiowa County, Colorado.

Western Regional Climate Center. 2022. Climate of Colorado, climate of the eastern plains. https://wrcc.dri.edu/Climate/narrative_co.php (accessed 9 August 2022).

Contributors

Doug Whisenhunt Ecological Site Specialist NRCS
Kimberly A. Diller
Ben P. Berlinger Rangeland Management Specialist NRCS Ret
Laura L. Craven MLRA Project Leader NRCS

Approval

Kirt Walstad, 9/07/2023

Acknowledgments

Project Staff:
Kimberly Diller, Ecological Site Specialist, NRCS MLRA, Pueblo Soil Survey Office (SSO)
Laura Craven, MLRA 69 Soil Survey Leader, NRCS MLRA Pueblo SSO
Amber Wyndham, Soil Scientist, NRCS MLRA Pueblo SSO
Ben Berlinger, Rangeland Management Specialist, Ret. NRCS La Junta, CO

Program Support:
Rachel Murph, NRCS State Rangeland Management Specialist
David Kraft, NRCS MLRA Ecological Site Specialist-QA (acting), Emporia, KS
Chad Remley, Regional Director, N. Great Plains Soil Survey, Salina, KS
B.J. Shoup, State Soil Scientist, Denver
Eugene Backhaus, State Resource Conservationist, Denver
Chanda Garcia, NRCS State Biologist, NRCS, Denver CO
Patty Knupp, Area 3 Biologist, NRCS, Pueblo CO

Partners/Contributors:
James Kulbeth, Natural Resources Specialist, Department of the Army, Fort Carson, CO
John Lamman, Rangeland Management Specialist, BLM, Cañon City, CO
Steve Olson, Botanist, USFS, Pueblo, CO
Renee Rondeau, Ecologist, CO Natural Heritage Program, Hesperus, CO
Terri Schultz, The Nature Conservancy, Ft. Collins, CO
John Valentine, District Manager, CO State Land Board, Pueblo, CO

Those involved in developing earlier versions of this site description include: Ben Berlinger, rangeland management specialist (RMS); Scott Woodall, RMS; Lee Neve, soil scientist; Julie Elliott, RMS; Terri Skadeland, Colorado State biologist; and Herman Garcia, Colorado State RMS.

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)	Ben Berlinger, Daniel Nosal, Kimberly Diller
Contact for lead author	Ben Berlinger, Area Rangeland Management Specialist, La Junta, CO,
Date	01/12/2005
Approved by	Kirt Walstad
Approval date
Composition (Indicators 10 and 12) based on	Annual Production