State 1
Tall and Medium Grasses, Forbs, Half-Shrub

Community 1.1
Tall and Medium Grasses, Forbs, Half-Shrub

This is the interpretive plant community and is considered to be the Historic Climax Plant Community (HCPC) for this site. This plant community contains a high diversity of tall and medium height, cool and warm season grasses (bluebunch wheatgrass, green or Columbia needlegrasses, thickspike or western wheatgrass, spike fescue, and plains muhly), and short grasses and sedges (Idaho fescue, Cusick bluegrass, Sandberg bluegrass, plains reedgrass, threadleaf and needleleaf sedge). There are abundant forbs (prairie clovers, dotted gayfeather) which occur in smaller percentages. Half shrubs such as winterfat should also be common. Shrubs such as mountain big sagebrush can also be present.

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 limited soil-water-plant relationship.

State 2
Medium and Short Grasses, Sedge, and Increaser Forbs

Community 2.1
Medium and Short Grasses, Sedge, and Increaser Forbs

Early stages of degradation, including non-prescribed grazing, will tend to change the HCPC to a community dominated by medium and short grasses and sedges such as Idaho fescue, thickspike/western wheatgrass, Sandberg bluegrass, threadleaf sedge, Cusick bluegrass, and prairie junegrass. Bluebunch wheatgrass can still be relatively abundant. Most of the othe taller and more palatable plants (spike fescue, tall needlegrasses, winterfat) will still be present but in smaller amounts. There may be an increase in the amount of some shrubs, particularly mountain big sagebrush. Palatable and nutritious forbs will be replaced by less desirable and more aggressive species such as fringed sagewort.

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.

Biomass production and litter become slightly reduced on the site with Community 2 as the taller grasses become replaced by shorter ones. 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, leafy spurge, dalmation toadflax, and sulphur cinquefoil.

State 3
Shrub, Short and Mid Increaser Grasses, Fringed Sagewort, Increaser Forbs, Cactus

Community 3.1
Shrub, Short and Mid Increaser Grasses, Fringed Sagewort, Increaser Forbs, Cactus

With continued heavy disturbance, the site will become dominated by species such as mountain big sagebrush, short and medium increaser grasses such as Sandberg bluegrass, plains reedgrass, prairie junegrass, western or thickspike wheatgrass, and Idaho fescue, fringed sagewort, and increaser forbs such as scarlet globemallow and Hood’s phlox. There may still be remnant amounts of some of the late-seral species such as bluebunch wheatgrass, spike fescue, and green/Columbia needlegrass present. The taller grasses will occur only occasionally, often under sagebrush plants. Palatable forbs will be mostly absent. Plains pricklypear cactus and rubber rabbitbrush may become common.

Plant community 3 is often less productive than 1 or 2. The lack of litter and short plant heights result in higher soil temperatures, poor water infiltration rates, and higher evapotranspiration rates, thus eventually favoring species that are more adapted to drier conditions. This community has lost many of the attributes of a healthy rangeland, including good infiltration, minimal erosion and runoff, nutrient cycling and energy flow.

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 are usually required to move it toward a higher successional stage and a more productive plant community. Practices such as prescribed burning and brush management are generally needed, along with extended rest and prescribed grazing once the community has degraded to this point. There are limitations to using mechanical treatment on this site due to the shallow soils.

Periodic wild fire will result in a community similar to number 3, but with a smaller component of big sagebrush for a few years. There may also be a slight decrease in the amount of fringed sagewort, depending on frequency, timing, and severity of the fire. However, these will soon return if there’s no change in grazing management.

State 4
Shrub, Half Shrubs, Weedy Forbs, Annuals, and Short Grasses

Community 4.1
Shrub, Half Shrubs, Weedy Forbs, Annuals, and Short Grasses

Further deterioration of community 3 results in a plant community dominated by mountain big sagebrush and undesirable plants such as fringed sagewort, broom snakeweed, plains pricklypear, weedy forbs (e.g., pussytoes and thistles), annuals such as cheatgrass and Japanese bromes and sixweeks fescue. Many increaser short grasses such as Sandberg bluegrass and plains reedgrass will be abundant. Frequently, a remnant population of climax species such as bluebunch wheatgrass will occur under sagebrush plants.
Rubber rabbitbrush can be abundant in some locations.
Plant community 4 produces less usable forage 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, such as cactus. A thick canopy cover (e.g., 20% or more) of big sagebrush often results in precipitation being intercepted, thus not reaching the soil. Most of the attributes of a healthy rangeland, including good infiltration, minimal erosion and runoff, nutrient cycling and energy flow, have been lost.

This community can respond positively to improved grazing management but it will take additional inputs to move it towards communities similar in production and composition to others that have been described. Once plants such as mountain big sagebrush become established, they are very difficult to remove and replace by grazing management alone. Additionally, the chances for success are significantly reduced.

Practices such as prescribed burning or brush management can reduce the amount of sagebrush, as well as some of the other susceptible plant species. The potential for success depends on the composiiion of the rest of the plant community. Because of the shallow soils (and sometimes, steeper slopes) associated with this ecological site, other practices such as mechanical treatment or seeding are generally not feasible nor recommended.