Natural Resources
Conservation Service
Ecological site R046XN601MT
Gravelly (Gr) RRU 46-N 13-19 PZ
Last updated: 7/19/2023
Accessed: 11/23/2024
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
| R046XN250MT |
Shallow (Sw) RRU 46-N 13-19 PZ |
|---|---|
| R046XN252MT |
Silty (Si) RRU 46-N 13-19 PZ |
| R046XN594MT |
Silty Steep (SiStp) RRU 46-N 13-19 PZ |
Similar sites
| R046XN261MT |
Very Shallow (VSw) RRU 46-N 15-19 PZ Very Shallow sites typically have a restrictive layer at less than 10 inches. |
|---|
Table 1. Dominant plant species
| Tree |
Not specified |
|---|---|
| Shrub |
Not specified |
| Herbaceous |
(1) Pseudoroegneria spicata |
Physiographic features
This ecological site can occur on outwash fans, hilltops, hills, plains and terrace escarpments. It often occurs in a complex with other ecological sites. This site occurs on all exposures and aspect can sometimes be significant. Variations in plant composition and production can occur due to aspect.
Table 2. Representative physiographic features
| Landforms |
(1)
Fan
(2) Hill (3) Plain |
|---|---|
| Flooding frequency | None |
| Ponding frequency | None |
| Slope | 0 – 70% |
| Water table depth | 152 cm |
| Aspect | Aspect is not a significant factor |
Climatic features
See Climatic Data Sheet for more details (Section II of the Field Office Technical Guide) or reference the following climatic web site: http://www.wrcc.sage.dri.edu/.
Table 3. Representative climatic features
| Frost-free period (characteristic range) | 57-84 days |
|---|---|
| Freeze-free period (characteristic range) | 109-120 days |
| Precipitation total (characteristic range) | 381-432 mm |
| Frost-free period (actual range) | 37-90 days |
| Freeze-free period (actual range) | 101-122 days |
| Precipitation total (actual range) | 356-432 mm |
| Frost-free period (average) | 69 days |
| Freeze-free period (average) | 114 days |
| Precipitation total (average) | 406 mm |
Figure 2. Monthly precipitation range
Figure 3. Monthly minimum temperature range
Figure 4. Monthly maximum temperature range
Figure 5. Monthly average minimum and maximum temperature
Figure 6. Annual precipitation pattern
Figure 7. Annual average temperature pattern
Climate stations used
-
(1) BABB 6 NE [USC00240392], Babb, MT
-
(2) AUGUSTA [USC00240364], Augusta, MT
-
(3) CASCADE 5 S [USC00241552], Cascade, MT
-
(4) ROGERS PASS 9 NNE [USC00247159], Wolf Creek, MT
Influencing water features
No influencing water features.
Soil features
These are moderately deep to very deep droughty soils formed in sand and gravel glacialfluvial deposits. They typically have greater than 15% pebbles and gravels in the upper part of the soil, and 50% or more pebbles, gravels, and cobbles in the lower part, often within 12 inches of the surface.
Table 4. Representative soil features
| Surface texture |
(1) Gravelly loam (2) Very gravelly sandy loam (3) Extremely gravelly loamy sand |
|---|---|
| Drainage class | Excessively drained |
| Permeability class | Moderate to rapid |
| Soil depth | 51 cm |
| Available water capacity (0-101.6cm) |
5.08 cm |
| Electrical conductivity (0-101.6cm) |
0 mmhos/cm |
| Soil reaction (1:1 water) (0-101.6cm) |
6.6 – 8.4 |
| Subsurface fragment volume <=3" (Depth not specified) |
15 – 50% |
| Subsurface fragment volume >3" (Depth not specified) |
5 – 25% |
Ecological dynamics
This site developed under Northern Rocky Mountain foothills climatic conditions, which included the natural influence of large herbivores and occasional fire. The plant community upon which interpretations are primarily based is the Historic Climax Plant Community (HCPC). This community is described as a reference to understand the original potential of this site, and is not always considered to be the management goal for every acre of rangeland. The following descriptions should enable the landowner or manager to better understand which plant communities occupy their land, and assist with setting goals for vegetation management. It can also be useful to understand the environmental and economic values of each plant community.
This site is considered moderately resilient to disturbance as it has moderate to severe soil limitations for plant growth. Changes may occur to the Historic Climax Plant Community due to management actions and/or climatic conditions. Under continued adverse impacts, a moderate decline in vegetative vigor and composition will occur. Under favorable vegetative management treatments this site can more readily return to the Historic Climax Plant Community (HCPC).
Continual adverse impacts to the site over a period of years results in a departure from the HCPC, with a decrease of the taller and more palatable species such as bluebunch wheatgrass, rough fescue, and plains muhly and an increase in Idaho fescue, needleandthread, threadleaf sedge, green sagewort, and yucca.
Plants that are not a part of the climax community that are most likely to invade are annual grasses and forbs and broom snakeweed. Noxious weeds that are likely to invade this site include spotted knapweed, dalmation toadflax, sulphur cinquefoil, and leafy spurge.
State and transition model
Figure 8. State and Transition Model
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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
Community 1.1
Tall and Medium Grasses, Forbs
This is the interpretive plant community and is considered to be the Historic Climax Plant Community (HCPC) for this site. This plant community is dominated by tall and medium cool and warm season grasses (bluebunch wheatgrass, rough fescue, Idaho fescue, needleandthread, and plains muhly). A few forbs such as dotted gayfeather and prairie clover occur in small percentages. Yucca, creeping and Rocky Mountain juniper are the predominant woody plants that occur. Annual production is low on this site due to low available water for plant growth. This plant community is well adapted to the Northern Rocky Mountain foothills climatic conditions. The diversity in plant species allows for drought tolerance. Individual species can vary greatly in production depending on growing conditions (timing and amount of precipitation, and temperature). This plant community is well suited to managed livestock grazing and provides diverse habitat for many wildlife species. Plants on this site have strong, healthy root systems that allow production to increase significantly with favorable moisture conditions. This plant community provides for soil stability and a properly functioning hydrologic cycle. 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. The soils associated with this site provide a marginal soil-water-plant relationship.
Figure 9. Annual production by plant type (representative values) or group (midpoint values)
Table 5. Annual production by plant type
| Plant type | Low (kg/hectare) |
Representative value (kg/hectare) |
High (kg/hectare) |
|---|---|---|---|
| Grass/Grasslike | 785 | 112 | 1457 |
| Shrub/Vine | – | 106 | 275 |
| Forb | – | 34 | 90 |
| Total | 785 | 252 | 1822 |
Table 6. Ground cover
| Tree foliar cover | 0% |
|---|---|
| Shrub/vine/liana foliar cover | 5-10% |
| Grass/grasslike foliar cover | 15-20% |
| Forb foliar cover | 1-5% |
| Non-vascular plants | 0-1% |
| 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 | 5-10% |
| Forb basal cover | 1-4% |
| Non-vascular plants | 0-1% |
| Biological crusts | 0% |
| Litter | 30-40% |
| Surface fragments >0.25" and <=3" | 0% |
| Surface fragments >3" | 30-50% |
| Bedrock | 0% |
| Water | 0% |
| Bare ground | 5-15% |
State 2
Medium and Short Grasses, Forbs, Shrub
Community 2.1
Medium and Short Grasses, Forbs, Shrub
Slight variations in the historical climax plant community result in a community dominated by medium and short grasses, with more half-shrubs and shrubs. Species that tend to dominate include needleandthread, with lesser amounts of bluebunch wheatgrass and rough fescue. Threadleaf sedge, green and fringed sagewort, and yucca become more prevalent. Biomass production and litter become reduced on the site with as the taller grasses become replaced by shorter ones, especially the non-native grasses. Evapotranspiration tends to increase, moisture retention is reduced, and soil surface temperatures increase. Some natural ecological processes will be altered. These plant communities provide for moderate soil stability. Increased amounts of bare ground can result in undesirable species invading. Common invaders can include spotted knapweed, dalmation toadflax, sulphur cinquefoil, and leafy spurge. This plant community will readily respond to improved grazing management, but a significant amount of time can be necessary to move it toward a higher successional stage and a more productive plant community similar to community 1.
State 3
Sedge, Sageworts, Shrub, Short and Mid Increaser Grasses, Increaser Forbs, Threeawns, and Cactus
Community 3.1
Sedge, Sageworts, Shrub, Short and Mid Increaser Grasses, Increaser Forbs, Threeawns, and Cactus
With continued heavy disturbance, the site will become dominated by short and medium increaser sedges and grasses such as threadleaf sedge, prairie junegrass, and Idaho fescue, green and fringed sagewort, and increaser forbs such as pussytoes and hairy goldenaster. There may still be remnant amounts of some of the late-seral species such as bluebunch wheatgrass and rough fescue present. The taller grasses will occur only occasionally. Palatable forbs will be mostly absent. Undesirable species such as Fendler’s or red threeawn, plains pricklypear cactus and broom snakeweed may become common. Annuals and weedy species may begin to be apparent. This plant community is the result of long-term, heavy, continuous grazing and/or annual, early spring seasonal grazing. Repeated spring grazing depletes stored carbohydrates, resulting in weakening and eventual death of the cool season tall and medium grasses. This plant community can occur throughout the pasture, on spot grazed areas, and around water sources where season-long grazing patterns occur. This community will respond positively to improved grazing management, but significant economic inputs along with a significant amount of time and extended rest are usually required to move it toward a higher successional stage and a more productive plant community. Using seeding and/or mechanical treatments on this site due to the shallow soils.
State 4
Sageworts, Half Shrub, Shrub, Threeawns, Cactus, Annuals and Weedy Species, Short Grasses
Community 4.1
Sageworts, Half Shrub, Shrub, Threeawns, Cactus, Annuals and Weedy Species, Short Grasses
Further deterioration of community 3 results in a plant community dominated by undesirable plants such as green and fringed sagewort, broom snakeweed, yucca, plains pricklypear cactus, weedy forbs (e.g., pussytoes and hairy goldenaster), annuals such as cheatgrass and Japanese bromes, and threeawns. Many increaser sedges and short grasses such as threadleaf sedge and prairie junegrass will be abundant. Most of the climax species such as bluebunch wheatgrass will be gone. Plant community 4 produces less usable forage for wildlife and livestock than the others described. The continuation of the downward trend and degradation of this site has resulted in higher soil surface temperatures, reduced water infiltration, and higher evapotranspiration. This has resulted in plant species that are more adapted to drier conditions, including cactus. Most of the attributes of a healthy rangeland, including good infiltration, minimal erosion and runoff, nutrient cycling and energy flow, have been lost. Community 4 can respond positively to improved grazing management but it will take several years along with significant additional inputs and extended rest to move it towards communities similar in production and composition to others that have been described. The feasibility and potential for using seeding or mechanical treatment to improve site health is extremely limited due to the gravel content and droughtiness of the soil, as well as landscape features.
Additional community tables
Table 8. Community 1.1 plant community composition
| Group | Common name | Symbol | Scientific name | Annual production (kg/hectare) | Foliar cover (%) | |
|---|---|---|---|---|---|---|
|
Shrub/Vine
|
||||||
| 0 | Shrubs and Half-shrubs | 0–275 | ||||
| Shrub, broadleaf | 2SB | Shrub, broadleaf | 0–90 | – | ||
| prairie sagewort | ARFR4 | Artemisia frigida | 0–90 | – | ||
| rubber rabbitbrush | ERNAN5 | Ericameria nauseosa ssp. nauseosa var. nauseosa | 0–90 | – | ||
| juniper | JUNIP | Juniperus | 0–90 | – | ||
| soapweed yucca | YUGL | Yucca glauca | 0–90 | – | ||
| plains pricklypear | OPPO | Opuntia polyacantha | 0–1 | – | ||
| broom snakeweed | GUSA2 | Gutierrezia sarothrae | 0–1 | – | ||
|
Grass/Grasslike
|
||||||
| 0 | Grasses and Sedges | 785–1457 | ||||
| bluebunch wheatgrass | PSSP6 | Pseudoroegneria spicata | 493–1367 | – | ||
| needle and thread | HECOC8 | Hesperostipa comata ssp. comata | 50–275 | – | ||
| rough fescue | FECA4 | Festuca campestris | 50–179 | – | ||
| Idaho fescue | FEID | Festuca idahoensis | 50–179 | – | ||
| plains muhly | MUCU3 | Muhlenbergia cuspidata | 0–179 | – | ||
| Cusick's bluegrass | POCU3 | Poa cusickii | 0–90 | – | ||
| Sandberg bluegrass | POSE | Poa secunda | 0–90 | – | ||
| prairie Junegrass | KOMA | Koeleria macrantha | 0–90 | – | ||
| needleleaf sedge | CADU6 | Carex duriuscula | 0–90 | – | ||
| threadleaf sedge | CAFI | Carex filifolia | 0–90 | – | ||
| plains reedgrass | CAMO | Calamagrostis montanensis | 0–90 | – | ||
| Grass, perennial | 2GP | Grass, perennial | 0–90 | – | ||
| tufted wheatgrass | ELMA7 | Elymus macrourus | 0–45 | – | ||
| western wheatgrass | PASM | Pascopyrum smithii | 0–45 | – | ||
| purple threeawn | ARPU9 | Aristida purpurea | 0–1 | – | ||
| Fendler's threeawn | ARPUF | Aristida purpurea var. fendleriana | 0–1 | – | ||
|
Forb
|
||||||
| 0 | Forbs | 0–90 | ||||
| beardtongue | PENST | Penstemon | 0–90 | – | ||
| spiny phlox | PHHO | Phlox hoodii | 0–90 | – | ||
| hairy false goldenaster | HEVI4 | Heterotheca villosa | 0–90 | – | ||
| narrowleaf stoneseed | LIIN2 | Lithospermum incisum | 0–90 | – | ||
| dotted blazing star | LIPU | Liatris punctata | 10–90 | – | ||
| western stoneseed | LIRU4 | Lithospermum ruderale | 0–90 | – | ||
| Forb, perennial | 2FP | Forb, perennial | 0–90 | – | ||
| pussytoes | ANTEN | Antennaria | 0–90 | – | ||
| spreading dogbane | APAN2 | Apocynum androsaemifolium | 0–90 | – | ||
| field sagewort | ARCA12 | Artemisia campestris | 10–90 | – | ||
| tarragon | ARDR4 | Artemisia dracunculus | 10–90 | – | ||
| miner's candle | CRVI4 | Cryptantha virgata | 10–90 | – | ||
| prairie clover | DALEA | Dalea | 10–90 | – | ||
| larkspur | DELPH | Delphinium | 0–1 | – | ||
| locoweed | OXYTR | Oxytropis | 0–1 | – | ||
Interpretations
Animal community
Livestock Grazing Interpretations: Managed livestock grazing is suitable on this site as it has the potential to produce a limited amount of high quality forage. Grazing must be managed carefully on this site to be sure livestock drift onto the better, more productive sites is not excessive. Management objectives should include maintenance or improvement of the plant community.
Using shorter grazing periods and providing for adequate re-growth after grazing are recommended for plant maintenance, health, and recovery. Continual non prescribed grazing of this site can be detrimental and will alter the plant composition and production over time. The result will be plant communities that resemble numbers 3 and 4, depending on how long this grazing management is used as well as other circumstances such as weather conditions and fire frequency.
Whenever Plant Community 2 (medium and short grasses) occurs, grazing management strategies that will prevent further degradation need to be implemented. This community is still stable, productive, and healthy provided it receives proper management. It will respond fairly quickly to improved grazing management, including increased growing season rest of key forage plants. Grazing management alone can usually move this back towards the potential / historic climax community.
Plant community 3 is the result of long-term, heavy, continuous grazing and/or annual, early spring seasonal grazing. Repeated heavy early spring grazing, especially during stem elongation (generally mid May through mid June), can also have detrimental affects on the taller, key forage species. Repeated spring grazing depletes stored carbohydrates, resulting in weakening and eventual death of the cool season tall and medium grasses. This plant community can occur throughout the pasture, on spot grazed areas, and around water sources where season-long grazing patterns occur.
It becomes critical at this point to implement a grazing strategy that will restore the stability and health of the site. Rest, usually for a number of years, can sometimes help with re-establishment of the desired species, depending on the amount of desirable species remaining.
Plant Community 4 has a high percentage of aggressive, less-desirable species. It has lost most of the attributes of a healthy rangeland. Grazing management alone is seldom able to restore the site to one that resembles the HCPC/PPC once this plant community has become established. There are limitations to using seeding and/or mechanical treatment on this site due to the droughty soils and often hilly landscape.
Calculating Safe Stocking Rates: Proper stocking rates should be incorporated into a grazing
management strategy that protects the resource, maintains or improves rangeland health, and is consistent with management objectives. Safe stocking rates will be based on useable forage production, and should consider ecological condition and trend of the site, and past grazing use history.
Calculations used to determine a safe stocking rate are based on the amount of useable forage available,
taking into account the harvest efficiency of the animal and the grazing strategy to be implemented. Average annual production must be measured or estimated to properly assess useable forage production and stocking rates.
Stocking rates are calculated from average forage production values using a 25% Harvest Efficiency factor for preferred and desirable plants, and 10% Harvest Efficiency for less desirable species. AUM calculations are based on 915 pounds (air-dry) per animal unit month (AUM) for a 1,000-pound cow with calf up to 4 months. No adjustments have been made for site grazability factors, such as steep slopes, site inaccessibility, or distance to drinking water.
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 AU! M/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).
Hydrological functions
The soils associated with this ecological site are generally in Hydrologic Soil Group A. The infiltration rates for these soils will normally be rapid to very rapid. The runoff potential for this site is low, depending on slope and ground cover/health. Runoff curve numbers generally range from 49 to 79.
For arid and semi-arid rangelands, good hydrologic conditions exist if cover (grass, litter, and brush canopy) is greater than 70%. Fair conditions exist when cover is between 30 and 70%, and poor conditions exist when cover is less than 30%.
Erosion is minor for sites in high similarity. Rills and gullies should not be present. Water flow patterns, if present, will be barely observable. Plant pedestals are essentially non-existent. Plant litter remains in place and is not moved by erosion. Soil surfaces should not be compacted or crusted.
Sites in low similarity (Plant Communities 3 and 4) are generally considered to be in less than good hydrologic condition. Sites in low similarity may have a high percentage of cover, but from shallow rooted species (e.g., threadleaf sedge). The deep root systems of the potential vegetation will help maintain or increase infiltration rates and reduce runoff. (Reference: Engineering Field Manual, Chapter 2 and Montana Supplement 4).
Recreational uses
This site provides some recreational opportunities for hiking,
horseback riding, big game and upland bird hunting. The forbs have flowers that appeal to photographers.
This site provides valuable open space and visual aesthetics.
Wood products
None
Supporting information
Contributors
Robert Leinard; Barbara Gibbons; Loretta Metz; Peter Husby
Approval
Kirt Walstad, 7/19/2023
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) | J. Siddoway, R. Bandy, G. Petersen |
|---|---|
| Contact for lead author | grant.petersen@usda.gov |
| Date | 04/19/2005 |
| Approved by | Kirt Walstad |
| Approval date | |
| Composition (Indicators 10 and 12) based on | Annual Production |
Indicators
-
Number and extent of rills:
Slopes most common on this site are between 0–15% and with at least 90% of the soil surface well-covered, rills, if evident will be rare, but may occur in bare areas after extreme convection storms – rills in this case would be narrow and less than 10 feet in length. -
Presence of water flow patterns:
Will be evident on this site with the steeper slopes, and with areas of bare ground, there may be areas which show accumulations of litter due to water movement, even after minor storm events. -
Number and height of erosional pedestals or terracettes:
Wind erosion will be rare on this site, but water erosion on the steeper slopes may have plants that could have pedestals and terracettes which could be 0.5 inch in height at the top of the slope and 1.0 inch towards the bottom of the slope. -
Bare ground from Ecological Site Description or other studies (rock, litter, lichen, moss, plant canopy are not bare ground):
Bare ground should be 10% or less on this site. -
Number of gullies and erosion associated with gullies:
Current gully erosion will not be evident on this site, but there may be gullies which have “healed” from the distant past. -
Extent of wind scoured, blowouts and/or depositional areas:
Appearance or evidence of these erosional features on the landscape would not be present on this site. -
Amount of litter movement (describe size and distance expected to travel):
Litter movement will be minimal on the gradual slopes, however on the steeper slopes there will be evidence of litter movement (i.e. debris dams) which may travel up to 10 feet. -
Soil surface (top few mm) resistance to erosion (stability values are averages - most sites will show a range of values):
Resistance to erosion will be high with soil stability values of 5 or 6; areas of bare soil on this site may have values less than 5 if not under plant canopy. -
Soil surface structure and SOM content (include type of structure and A-horizon color and thickness):
Soil surface structure is granular; A horizon depth is 1 – 4”. -
Effect of community phase composition (relative proportion of different functional groups) and spatial distribution on infiltration and runoff:
Dominance of taller, deep rooted bunchgrasses will maximize infiltration and minimize runoff throughout the site. -
Presence and thickness of compaction layer (usually none; describe soil profile features which may be mistaken for compaction on this site):
Will not be present generally, but there may be areas that have “healed” from former bison trails and wallows as well as more current livestock trails which could have a compaction layer below the soil surface. In some instances the Bk horizon maybe cemented and act like a compacted layer, restricting root penetration. -
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:
Cool season, taller grasses (bluebunch wheatgrass)Sub-dominant:
cool season mid-grasses (Idaho fescue, needle and thread) = shrubs > cool season rhizomatous grasses (western wheatgrass) = warm season bunchgrass (plains muhly) = perennial forbs = cool season short grasses (Sandberg bluegrass) = sedges (threadleaf sedge)Other:
Additional:
-
Amount of plant mortality and decadence (include which functional groups are expected to show mortality or decadence):
Will be low for all functional groups in a given year. Prolonged droughts which last more than 3 years may show increases in mortality and decadence for all plant groups. -
Average percent litter cover (%) and depth ( in):
-
Expected annual annual-production (this is TOTAL above-ground annual-production, not just forage annual-production):
900 - 1600 #/acre. This would be the expected production for the reference state during adequate moisture years. 1375 pounds would be the expected production in a 17 inch precipitation zone. -
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:
Dense clubmoss, blue grama, red threeawn, field brome, a variety of annual or biennial weedy forbs, fringed sagewort, green sagewort, broom snakeweed, prickly pear cactus, yucca, prairie rose, creeping juniper, cheatgrass. -
Perennial plant reproductive capability:
During adequate moisture years bunchgrasses will generally produce seeds, however the cool season rhizomatous grasses may not necessarily produce seed even with adequate moisture.
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