Natural Resources
Conservation Service
Ecological site R058AC059MT
Shallow Clay (SwC) RRU 58A-C 11-14" p.z.
Last updated: 6/14/2023
Accessed: 11/21/2024
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.
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.
Associated sites
| R058AC041MT |
Clayey (Cy) RRU 58A-C 11-14" p.z. |
|---|---|
| R058AC049MT |
Silty-Steep (SiStp) RRU 58A-C 11-14" p.z. (combined R058AC046MT, R058AC047MT & R058AC048MT into this site) |
| R058AC057MT |
Shallow (Sw) RRU 58A-C 11-14" p.z. |
Similar sites
| R058AC057MT |
Shallow (Sw) RRU 58A-C 11-14" p.z. The Shallow site differs by having a different texture, and generally being over sandstone or loamy beds. |
|---|---|
| R058AC049MT |
Silty-Steep (SiStp) RRU 58A-C 11-14" p.z. (combined R058AC046MT, R058AC047MT & R058AC048MT into this site) The Clayey-Steep site is over 20 inches deep to root restricting materials, as well as occurring on slopes over 15%. |
| R058AC041MT |
Clayey (Cy) RRU 58A-C 11-14" p.z. Clayey sites have similar textures, but differ mainly by being over 20 inches to rock and having significantly more production. The plant community can be similar because of the restrictive layers of clayey textures. |
Table 1. Dominant plant species
| Tree |
Not specified |
|---|---|
| Shrub |
(1) Artemisia frigida |
| Herbaceous |
(1) Pseudoroegneria spicata |
Physiographic features
This ecological site can occur on nearly
level to very steep uplands. It often occurs in complex with other ecological sites, particularly in rougher terrain. This site occurs on all slopes and exposures. Slight variations in plant community composition and production can result due to aspect. The amount of exposed rock outcrop tends to increase as slopes increase. Runoff and the potential for water erosion can be important features of this site.
Table 2. Representative physiographic features
| Landforms |
(1)
Hill
(2) Escarpment |
|---|---|
| Flooding frequency | None |
| Ponding frequency | None |
| Elevation | 2,250 – 4,500 ft |
| Slope | 70% |
| Water table depth | 60 in |
Climatic features
Major Land Resource Area (MLRA) 58AC in Montana is considered to have a continental climate characterized by cold winters, hot summers, low humidity, light rainfall, and much sunshine. Extremes in temperature are typical. The climate is the result of this MLRA’s location in the geographic center of North America. There are few natural barriers on the northern Great Plains and the winds move freely across the plains and account for rapid changes in temperature. Seasonal precipitation is often limiting for plant growth. Annual fluctuations in species composition and total production are typical depending on the amount and timing of rainfall.
Temperatures can be very extreme in this part of Montana. Summer daytime temperatures are typically quite warm, generally averaging in the mid to upper 80º’s F for July and August. Summertime temperatures will typically reach in the 100º’s F at some point during the summer, and can reach 90º F any month between May and September. Conversely, winter temperatures can be cold, averaging in the mid teens to mid 20º’s F for December and January. There will typically be several days of below zero temperatures each winter. It is not uncommon for temperatures to reach 30–40º F below zero, or even colder, most any winter.
Spring can be windy throughout this MLRA, with winds averaging over 10 mph about 15 percent of the time. Speeds of 50 mph or stronger can occasionally occur as a weather system crosses this part of Montana.
The majority of the rangeland in MLRA 58AC is within the 11 to 14 inch Mean Annual Precipitation (MAP) range. During an average year, 70 to 75 percent of the annual precipitation falls between April and September, which are the primary growing season months.
Snowfall is not heavy in the area, averaging 28 total inches in the Yellowstone Valley. Heavy snowfall occurs infrequently, usually late in the winter or early spring. Snow cover is typically 1 to 3 inches.
The frost-free (32º F.) season averages about 105 to 145 days each year in the uplands, to nearly 170 days along the Yellowstone River Valley.
For local climate station information, refer to http://www.wcc.nrcs.usda.gov/cgibin/state.pl?state=mt.
Table 3. Representative climatic features
| Frost-free period (average) | 135 days |
|---|---|
| Freeze-free period (average) | 155 days |
| Precipitation total (average) | 14 in |
Influencing water features
Soil features
These are clayey soils that are 10 to 20 inches deep to underlying beds of decomposed shale or nearly impervious clays. Few roots penetrate deeper than 20 inches. Available Water Holding Capacity to 20 inches is 2 to 4 inches.
Table 4. Representative soil features
| Soil depth | 10 – 20 in |
|---|---|
| Available water capacity (0-40in) |
2 – 4 in |
Ecological dynamics
The following are descriptions of several plant communities that may occupy this site:
State and transition model
More interactive model formats are also available.
View Interactive Models
More interactive model formats are also available.
View Interactive Models
Click on state and transition labels to scroll to the respective text
State 1 submodel, plant communities
State 2 submodel, plant communities
State 3 submodel, plant communities
State 4 submodel, plant communities
State 1
Tall and Medium Grasses/ Forbs/ Shrubs (HCPC)
Community 1.1
Tall and Medium Grasses/ Forbs/ Shrubs (HCPC)
The physical aspect of this site in the Historical Climax (HCPC) is that of a gentle to steep sloping grassland with scattered shrubs on steeper slopes. Approximately 70–75% of the annual production is from grasses and sedges, 5–10% from forbs, and 5–15% is from shrubs and half-shrubs. The canopy cover of shrubs is 1-5%. Dominant species include bluebunch wheatgrass, green needlegrass, plains muhly, and western or thickspike wheatgrass. Short grasses such as Sandberg bluegrass and prairie junegrass are also present. There are abundant forbs (purple and white prairie clover, prairie coneflower, dotted gayfeather) which occur in smaller percentages. Shrubs such as Nuttall’s saltbush and winterfat are common. Rocky Mountain juniper may also occur on steeper slopes. The occurrence, frequency, timing, and intensity of fire all have an important affect on this community. The Wyoming big sagebrush is susceptible to fire and will tend to decrease with fire. The Nuttall’s saltbush tends to be resistant to fire. Winterfat is very susceptible to burning, depending on the intensity. Some published reports indicate that spring burning may be least detrimental. Reports indicate further that fall burning has resulted in a 95 to 100 percent loss of winterfat in some situations. This plant community is well adapted to the Northern Great Plains climatic conditions. The diversity in plant species and presence of tall, deep-rooted perennial grasses allows for drought tolerance. Plants on this site have strong, healthy root systems that allow production to increase significantly with favorable moisture conditions. Abundant plant litter is available for soil building and moisture retention. Plant litter is properly distributed with very little movement off-site and natural plant mortality is very low. This plant community provides for soil stability and a functioning hydrologic cycle.
Figure 2. 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 | 783 | 909 | 1044 |
| Shrub/Vine | 90 | 108 | 120 |
| Forb | 27 | 33 | 36 |
| Total | 900 | 1050 | 1200 |
Table 6. Ground cover
| Tree foliar cover | 0% |
|---|---|
| Shrub/vine/liana foliar cover | 1-5% |
| Grass/grasslike foliar cover | 40-60% |
| Forb foliar cover | 5-10% |
| Non-vascular plants | 0% |
| Biological crusts | 0% |
| Litter | 0% |
| Surface fragments >0.25" and <=3" | 0% |
| Surface fragments >3" | 0% |
| Bedrock | 0% |
| Water | 0% |
| Bare ground | 0% |
Table 7. Soil surface cover
| Tree basal cover | 0% |
|---|---|
| Shrub/vine/liana basal cover | 1-5% |
| Grass/grasslike basal cover | 5-12% |
| Forb basal cover | 1-4% |
| Non-vascular plants | 0% |
| Biological crusts | 0-5% |
| Litter | 40-60% |
| Surface fragments >0.25" and <=3" | 5-10% |
| Surface fragments >3" | 0% |
| Bedrock | 0% |
| Water | 0% |
| Bare ground | 15-30% |
Table 8. Canopy structure (% cover)
| Height Above Ground (ft) | Tree | Shrub/Vine | Grass/ Grasslike |
Forb |
|---|---|---|---|---|
| <0.5 | – | 1-5% | – | 5-10% |
| >0.5 <= 1 | – | – | – | – |
| >1 <= 2 | – | – | 40-60% | – |
| >2 <= 4.5 | – | – | – | – |
| >4.5 <= 13 | – | – | – | – |
| >13 <= 40 | – | – | – | – |
| >40 <= 80 | – | – | – | – |
| >80 <= 120 | – | – | – | – |
| >120 | – | – | – | – |
State 2
Medium and Short Grasses/ Shrubs
Community 2.1
Medium and Short Grasses/ Shrubs
This community occurs from shifts in climate or other disturbances, such as grazing that tend to increase Wyoming big sagebrush. Dominant grasses include western or thickspike wheatgrass, Sandberg bluegrass, and prairie junegrass. Bluebunch wheatgrass, green needlegrass, and plains muhly will still be present but in smaller amounts. Palatable and nutritious forbs will be replaced by less desirable and more aggressive species, such as hairy goldenaster, silverleaf scurfpea, and scarlet globemallow. Sweet clover is a common invader on this ecological site. Grass biomass production and litter become reduced on Community 2 as the taller grasses become less prevalent, increasing evaporation and reducing moisture retention. Additional open space in the community can result in undesirable invader species. This plant community provides for moderate soil stability.
State 3
Shrubs and Half-shrubs/ Short Grasses
Community 3.1
Shrubs and Half-shrubs/ Short Grasses
This is a disturbance induced community, with dominant species including Wyoming big sagebrush, Sandberg bluegrass, prairie junegrass, blue grama, perennial forbs, and fringed sagewort. Remnant amounts of western or thickspike wheatgrass and needleandthread may be present. Tall grasses and palatable forbs will be mostly absent. Plant Community 3 is much less productive than Plant Communities 1 or 2, and has lost many of the attributes of a healthy rangeland. The loss of deep perennial root systems reduces total available moisture for plant growth. Reduction of plant litter will result in higher surface soil temperatures and increased evaporation losses. Annual species are often aggressive and competitive with seedlings of perennial plants. This community can respond positively to improved grazing management but it will take additional inputs to move it towards a community similar in production and composition to that of Plant Community 1 or 2.
State 4
Shrubs/ Half-shrubs/ Annual Grasses and Forbs/ Short Grasses
Community 4.1
Shrubs/ Half-shrubs/ Annual Grasses and Forbs/ Short Grasses
This community is the result of continual adverse disturbances. Dominant species include Wyoming big sagebrush, fringed sagewort and broom snakeweed, and annuals such as cheatgrass, Japanese brome, and six-weeks fescue. Blue grama, Sandberg bluegrass, and prairie junegrass may be present in lesser amounts. Plant community 4 has extremely reduced production of native plants (< 400 lbs. /acre). The lack of litter and short plant heights result in higher soil temperatures, poor water infiltration rates, and increased evaporation, which gives short sod grasses and annual invaders a competitive advantage over the tall and medium grasses. This community has lost many of the attributes of a healthy rangeland, including good infiltration, minimal erosion and runoff, nutrient cycling and energy flow. Significant economic inputs and time would be required to move this plant community toward a higher successional stage and a more productive plant community.
Additional community tables
Table 9. Community 1.1 plant community composition
| Group | Common name | Symbol | Scientific name | Annual production (lb/acre) | Foliar cover (%) | |
|---|---|---|---|---|---|---|
|
Grass/Grasslike
|
||||||
| 1 | Native grasses | 630–960 | ||||
| green needlegrass | NAVI4 | Nassella viridula | 270–720 | – | ||
| western wheatgrass | PASM | Pascopyrum smithii | 45–180 | – | ||
| bluebunch wheatgrass | PSSP6 | Pseudoroegneria spicata | 45–180 | – | ||
| tufted wheatgrass | ELMA7 | Elymus macrourus | 45–180 | – | ||
| needle and thread | HECOC8 | Hesperostipa comata ssp. comata | 0–60 | – | ||
| plains muhly | MUCU3 | Muhlenbergia cuspidata | 0–60 | – | ||
| 2 | Native grasses and sedges | 0–120 | ||||
| Grass, perennial | 2GP | Grass, perennial | 0–60 | – | ||
| blue grama | BOGR2 | Bouteloua gracilis | 0–60 | – | ||
| needleleaf sedge | CADU6 | Carex duriuscula | 0–60 | – | ||
| threadleaf sedge | CAFI | Carex filifolia | 0–60 | – | ||
| plains reedgrass | CAMO | Calamagrostis montanensis | 0–60 | – | ||
| prairie Junegrass | KOMA | Koeleria macrantha | 0–60 | – | ||
| Sandberg bluegrass | POSE | Poa secunda | 0–60 | – | ||
|
Forb
|
||||||
| 3 | Native forbs | 9–60 | ||||
| Forb, perennial | 2FP | Forb, perennial | 9–12 | – | ||
| common yarrow | ACMI2 | Achillea millefolium | 9–12 | – | ||
| pussytoes | ANTEN | Antennaria | 9–12 | – | ||
| tufted milkvetch | ASSP6 | Astragalus spatulatus | 9–12 | – | ||
| milkvetch | ASTRA | Astragalus | 9–12 | – | ||
| miner's candle | CRVI4 | Cryptantha virgata | 9–12 | – | ||
| white prairie clover | DACA7 | Dalea candida | 9–12 | – | ||
| purple prairie clover | DAPU5 | Dalea purpurea | 9–12 | – | ||
| buckwheat | ERIOG | Eriogonum | 9–12 | – | ||
| hairy false goldenaster | HEVI4 | Heterotheca villosa | 9–12 | – | ||
| dotted blazing star | LIPU | Liatris punctata | 9–12 | – | ||
| desertparsley | LOMAT | Lomatium | 9–12 | – | ||
| evening primrose | OENOT | Oenothera | 9–12 | – | ||
| beardtongue | PENST | Penstemon | 9–12 | – | ||
| spiny phlox | PHHO | Phlox hoodii | 9–12 | – | ||
| scurfpea | PSORA2 | Psoralidium | 9–12 | – | ||
| upright prairie coneflower | RACO3 | Ratibida columnifera | 9–12 | – | ||
| scarlet globemallow | SPCO | Sphaeralcea coccinea | 9–12 | – | ||
| prairie thermopsis | THRH | Thermopsis rhombifolia | 9–12 | – | ||
| American vetch | VIAM | Vicia americana | 9–12 | – | ||
| 4 | Native forbs (toxic properties) | 0–1 | ||||
| twogrooved milkvetch | ASBI2 | Astragalus bisulcatus | 0–1 | – | ||
| larkspur | DELPH | Delphinium | 0–1 | – | ||
| white locoweed | OXSE | Oxytropis sericea | 0–1 | – | ||
| deathcamas | ZIGAD | Zigadenus | 0–1 | – | ||
|
Shrub/Vine
|
||||||
| 5 | Native shrubs and half-shrubs | 9–60 | ||||
| Wyoming big sagebrush | ARTRW8 | Artemisia tridentata ssp. wyomingensis | 9–60 | – | ||
| Nuttall's saltbush | ATNU2 | Atriplex nuttallii | 9–60 | – | ||
| winterfat | KRLA2 | Krascheninnikovia lanata | 9–60 | – | ||
| 6 | Native shrubs and half-shrubs | 0–120 | ||||
| Shrub, broadleaf | 2SB | Shrub, broadleaf | 0–60 | – | ||
| silver sagebrush | ARCA13 | Artemisia cana | 0–60 | – | ||
| prairie sagewort | ARFR4 | Artemisia frigida | 0–60 | – | ||
| yellow rabbitbrush | CHVI8 | Chrysothamnus viscidiflorus | 0–60 | – | ||
| rubber rabbitbrush | ERNAN5 | Ericameria nauseosa ssp. nauseosa var. nauseosa | 0–60 | – | ||
| prairie rose | ROAR3 | Rosa arkansana | 0–60 | – | ||
| 7 | Native shrubs and half-shrubs | 0–1 | ||||
| broom snakeweed | GUSA2 | Gutierrezia sarothrae | 0–1 | – | ||
| plains pricklypear | OPPO | Opuntia polyacantha | 0–1 | – | ||
Interpretations
Animal community
Livestock Grazing Interpretations:
Managed livestock grazing is suitable on this site as it has the potential to produce a moderate amount of high quality forage. Forage production is somewhat limited by steep slopes and shallow soils, and the potential for runoff, which reduces the effectiveness of the precipitation received for plant growth. The steeper slopes may also limit livestock travel and result in poor grazing distribution, especially in areas away from water. Management objectives should include maintenance or improvement of the plant community. Shorter grazing periods and adequate re-growth after grazing are recommended for plant maintenance and recovery. Heavy stocking and season long use of this site can be detrimental and will alter the plant community composition and production over time.
Whenever Plant Community 2 (medium and short grasses) occurs, grazing management strategies need to be implemented to avoid further deterioration. This community is still stable, productive, and healthy provided it receives proper management. This community will respond fairly quickly to improved grazing management, including increased growing season rest of key forage plants. Grazing management alone can usually move this community back towards the potential community.
Plant Communities 3 and 4 have substantially reduced forage production, and a high percentage of aggressive, non-palatable species. Once these plant communities become established, it will be much more difficult to restore the site to a community that resembles the potential with grazing management alone. Additional growing season rest and some type of brush management is often necessary for re-establishment of the desired species and to restore the stability and health of the site.
Wildlife Interpretations:
Complex topography and vegetative structure, along with the tendency to occur in a mosaic with other ecological sites make this site an important component of wildlife habitat diversity. Big game species are particularly attracted to this site, where it occurs in rough topography, because of thermal cover and winter range values. South slopes tend to stay open in winter where important browse species such as winterfat and Nuttall’s saltbush are available. Rock outcrops and scattered Rocky Mountain junipers provide hunting perches for a variety of raptors. Golden eagles often hunt low to the ground along the steep sidehills characteristic of this site where they can surprise small mammals as they cruise over small drainages. Ferruginous hawks may nest on rock outcrops. Sites having steeper, rocky topography provide habitat for interesting songbird species such as rock wrens, canyon wrens and spotted towhees. Scattered junipers and pines host field sparrows and chipping sparrows. Springs and seeps may occur along toe slopes. These provide habitat for amphibians and many other wildlife species.
Plant Community 1: Tall and Medium Grasses/ Forbs/ Shrubs (HCPC):
The diversity of forbs, half-shrubs and shrubs provides feeding substrate for a variety of pollinating insects, which are prey for many birds, reptiles and small mammals. Springs and seeps provide habitat for amphibians such as tiger salamanders. The short-horned lizard is a representative reptile. The diversity of plant species and life forms, in combination with topographic variation, provides high quality bird habitat. Lark sparrows, chipping sparrows, rock wrens and ferruginous hawks are examples of birds using this community. Sharp-tailed grouse and sage grouse may use this community for lek sites on ridge tops and fairly level topography. The predominance of grasses plus a diversity of forbs, shrubs and half-shrubs in this community favors grazers and mixed feeders such as bison, pronghorn and elk. Winter range value is often high for mule deer and pronghorn when topographic diversity provides south exposures and browse plants such as Nuttall’s saltbush and winterfat are available. Small mammal diversity may be fairly high. Example species include the kangaroo rat, deer mouse, olive-backed pocket mouse and desert cottontail.
Plant Community 2: Medium and Short Grasses/ Shrubs:
Pollinator insect species diversity may decline with the loss of some succulent, palatable forbs. Livestock trampling and grazing around springs and seeps degrades amphibian habitat. A reduction in litter cover and residual plant material during early spring decreases nesting habitat value for sage grouse and other ground-nesting birds. The potential increase in big sagebrush cover may benefit sage grouse nesting and winter habitat to some extent. Pronghorn and mule deer still find winter browse but overall nutrition value declines with the reduction in winterfat and Nuttall’s saltbush cover. Herbivorous small mammals, such as voles, may decline with the reduction in litter cover.
Plant Community 3: Shrubs and Half-shrubs/ Short Grasses:
Insect species diversity further declines with the simplification of the plant community, although some species, such as grasshoppers, may be very abundant during population highs. The general drying of the site following loss of litter cover and residual vegetation continues to degrade amphibian habitat. Sparse vegetation and increased bare ground may provide suitable habitat for a few nesting bird species (i.e. horned larks) but the lack of complex vegetative structure and residual cover makes this community poor habitat in general for most ground-nesting birds and relatively poor big game habitat. Pronghorn and mule deer may forage in this type throughout the year. However, nutritional levels for big game are greatly reduced and are available for a much shorter period as compared to the HCPC.
Plant Community 4: Shrubs and Half-shrubs/ Annual Grasses and Forbs/ Short Grasses:
Insects may be very abundant during population highs (i.e. grasshoppers) but diversity is low, especially of pollinators. Amphibian habitat is very degraded; ephemeral pools evaporate rapidly and the soil surface is very dry and hot during summer. Ground nesting bird habitat value is poor because of the lack of litter cover and residual plant cover in early spring. Sage grouse and Brewer’s sparrows may be fairly abundant in the heavier sagebrush cover but probably suffer heavy losses while nesting on the poorly protected ground surface. Mountain plovers prefer to nest in this community type if a somewhat pebbly surface is present. Mule deer and pronghorn may utilize sagebrush and fringed sagewort during winter in this community.
Hydrological functions
The soils associated with this ecological site are generally in Hydrologic Soil Group D. The infiltration rates for these soils will normally be slow to very slow. The runoff potential for this site is moderate to high, depending on slope and ground cover/health. Runoff curve numbers generally range from 79 to 94.
Other information
The following is an example of how to calculate the recommended stocking rate. This example does not use production estimates from this specific ecological site. You will need to adjust the annual production values and run the calculations using total annual production values from the ecological sites encountered on each individual ranch/pasture. Before making specific recommendations, an on-site evaluation must be made.
Example of total annual production amounts by type of year:
Favorable years = 2200 lbs/acre
Normal years = 1480 lbs/acre
Unfavorable years = 1200 lbs/acre
It is recommended that on slopes of 30% or less, stocking rate should be derived from the total annual production pounds minus 500 pounds for residual dry matter and 25% harvest efficiency. On slopes over 30%, stocking rate is derived from total annual production pounds minus 800 pounds for residual dry matter and 25% harvest efficiency. Refer to the NRCS National Range and Pasture Handbook for a list of Animal Unit Equivalents.
Sample Calculations using Favorable Year production amounts:
< 30% slopes: AUM/AC = [(2200-500)(0.25)]/915 lbs/month for one AU = 0.46 AUM/AC
AC/AUM = (1.0 AU)/(0.46AUM/AC) = 2.2 AC/AUM
> 30% slopes: AUM/AC = [(2200-800)(0.25)]/915 lbs/month for one AU = 0.38 AUM/AC
AC/AUM = (1.0 AU)/(0.38 AUM/AC) = 2.6 AC/AUM
NOTE: 915 lbs/month for one Animal Unit is used as the baseline for maintenance requirements. This equates to 30 lbs/day of air-dry forage (1200 lb cow at 2.5% of body weight).
Supporting information
Inventory data references
Supporting Data for Site Development:
NRCS Production & Composition Record for Native Grazing Lands (Range-417): 3
BLM Soil & Vegetation Inventory Method (SVIM) Data: 6
NRCS Range Condition Record (ECS-2): 10
NRCS Range/Soil Correlation Observations & Soil 232 notes: 10
Ecological Site Reference:
NRCS 417 No.: Sweetgrass County 506 & 516, Musselshell County 516
Field Offices where this site occurs within the state:
Big Sandy
Big Timber
Billings
Chinook
Columbus
Crow Agency
Fort Belknap
Hardin
Harlowton
Joliet
Lewistown
Malta
Roundup
Stanford
White Sulphur Springs
Winnett
Other references
Site Documentation:
Authors:
Original: NRCS, 1983
Revised: Matthew J. Ricketts, Robert E. Leiland, Rhonda Sue Noggles, Peter O. Husby, 2003
Contributors
MJR, REL, RSN, POH
RSN
Approval
Kirt Walstad, 6/14/2023
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) | Loretta Metz |
|---|---|
| Contact for lead author | |
| Date | 04/06/2005 |
| Approved by | Kirt Walstad |
| Approval date | |
| Composition (Indicators 10 and 12) based on | Annual Production |
Indicators
-
Number and extent of rills:
Rills should not be evident in the reference state. Exceptions include steep slopes (>55%) following heavy thunderstorms. Rills may then be present, but will generally be less than 8 feet in length. -
Presence of water flow patterns:
Water flow patterns are generally not evident on lesser slopes, but can be apparent on steeper slopes in the reference state. When they are present, they are short (< 2 feet long) and discontinuous. -
Number and height of erosional pedestals or terracettes:
Both may be evident in the reference state, especially on steeper slopes (>45%). If present, they do not exceed 1.5 inches in height. -
Bare ground from Ecological Site Description or other studies (rock, litter, lichen, moss, plant canopy are not bare ground):
Bare ground is less than 30% in the reference state. In HCPC, bare ground should not exceed 18%. -
Number of gullies and erosion associated with gullies:
Gully erosion is not evident in the reference state. -
Extent of wind scoured, blowouts and/or depositional areas:
These are not evident in the reference state. -
Amount of litter movement (describe size and distance expected to travel):
Litter movement varies by size and depth of litter. In the reference state, litter should be coarse perennial grass leaves, anywhere from 1.5 inches up to 3 inches in length, plus small shrub leaves. Litter will not move more than a couple of inches from where it originated. -
Soil surface (top few mm) resistance to erosion (stability values are averages - most sites will show a range of values):
Stability values of 4-5 in plant interspaces. Stability values of 5-6 under plant canopies and at plant bases. -
Soil surface structure and SOM content (include type of structure and A-horizon color and thickness):
Granular surface structure of 1 to 3 inches in depth; brown color. Organic matter approx 1-3%. -
Effect of community phase composition (relative proportion of different functional groups) and spatial distribution on infiltration and runoff:
Deep-rooted native perennial grasses optimize infiltration and runoff. Perennial plants (grasses, forbs and shrubs) should be spaced approximately 2 to 3 feet apart in the reference state. -
Presence and thickness of compaction layer (usually none; describe soil profile features which may be mistaken for compaction on this site):
No compaction layer present in reference state. -
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:
Mid-height, native perennial bunchgrasses >> shrubs >= native perennial and annual forbs.Sub-dominant:
Other:
Additional:
-
Amount of plant mortality and decadence (include which functional groups are expected to show mortality or decadence):
Plant mortality of deep-rooted perennial bunchgrases is very low; mortality of shrubs is very low. Decadence during periods of prolonged drought will be evident on all plant species. -
Average percent litter cover (%) and depth ( in):
-
Expected annual annual-production (this is TOTAL above-ground annual-production, not just forage annual-production):
900 – 1200 #/acre. -
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:
plains pricklypear, broom snakeweed, cheatgrass, Japanese brome, curlycup gumweed, Wyoming big sagebrush, fringed sagewort, blue grama. -
Perennial plant reproductive capability:
This is not impaired in the reference state.
Print Options
Sections
Font
Other
The Ecosystem Dynamics Interpretive Tool is an information system framework developed by the USDA-ARS Jornada Experimental Range, USDA Natural Resources Conservation Service, and New Mexico State University.
Click on box and path labels to scroll to the respective text.