The site developed under Northern Great Plains climatic conditions, and included natural influence of large herbivores and occasional fire. Changes will occur in the plant communities due to climatic conditions and/or management actions. Due to the nature of the soils, the site is considered quite stable. Under continued adverse impacts, a slow decline in vegetative vigor and composition will occur. Under favorable vegetative management treatments the site can quickly return to the Reference Plant Community.
The plant community upon which interpretations are primarily based is the Reference Plant Community. The Reference Plant Community has been determined by study of rangeland relic areas, areas protected from excessive disturbance, and areas under long-term rotational grazing regimes. Trends in plant community dynamics ranging from heavily grazed to lightly grazed areas, seasonal use pastures, and historical accounts also have been used. Subclimax plant communities, states, transitional pathways, and thresholds have been determined through similar studies and experience.
Heavy continuous grazing and/or continuous seasonal (spring) grazing, without adequate recovery periods following each grazing occurrence causes this site to depart from the Reference Plant Community. Blue grama and buffalograss will begin to increase. Western wheatgrass will increase initially and then begin to decrease. Green needlegrass will decrease in frequency and production. In time, heavy continuous grazing will likely cause blue grama and buffalograss to dominate and pioneer perennials, annuals, and club moss (in its range) to increase. This plant community is relatively stable and the competitive advantage prevents other species from establishing. This plant community is less productive than the Reference Plant Community. Runoff increases and infiltration will decrease. Soil erosion will be minimal.
Extended periods of non-use and/or lack of fire will result in a plant community having high litter levels, which favors an increase in Kentucky bluegrass and/or smooth bromegrass.
Due to a general invasion of exotic species (such as Kentucky bluegrass and smooth bromegrass) across the MLRA within this site, returning to the Reference Plant Community Phase may not be possible.
Following the state and transition diagram are narratives for each of the described states and community phases. These may not represent every possibility, but they are the most prevalent and repeatable states/community phases. The plant composition tables shown below have been developed from the best available knowledge at the time of this revision. As more data are collected, some of these community phases and/or states may be revised or removed, and new ones may be added. The main purpose for including the descriptions here is to capture the current knowledge and experience at the time of this revision.
The Grassland State is supported by empirical data, historical data, local expertise, and photographs. This state is defined by three native plant communities that are a result of periodic fire, drought, and grazing. These events are part of the natural disturbance regime and climatic process. The Reference Plant Community consists of both warm- and cool-season, tall- and midgrasses, forbs, shrubs. Plant Community 1.2 the Shortgrass cool-season community is dominated by blue grama and western wheatgrass. The Non-Use Plant Community 1.3 consists of decadent plants or excessive litter, and few remnant native grasses and forbs.
Reference Plant Community
This is the interpretive plant community and is considered to be the Reference Plant Community Phase. This community evolved with grazing by large herbivores and occasional prairie fires and can be found on areas that are properly managed with grazing and/or prescribed burning, and sometimes on areas receiving occasional short periods of rest.
The potential vegetation is about 90% grasses or grass-like plants, 5% forbs, and 5% shrubs. Green needlegrass and western wheatgrass dominate the plant community. Other grasses and grass-like plants include thickspike wheatgrass, needleandthread, blue grama, porcupine grass, buffalograss, prairie junegrass, and sedges. Significant forbs include scurfpea, Lambert’s crazyweed, scarlet globemallow, cudweed sagewort, and western yarrow. In many areas western snowberry is the principal shrub and occurs in patchy mosaics. In other areas, silver sagebrush is the dominant shrub and occurs more evenly dispersed across the site. Other shrubs include prairie rose, leadplant, winterfat, and fringed sagewort.
This plant community is well adapted to the Northern Great Plains climatic conditions. Individual species can vary greatly in production depending on growing conditions (timing and amount of precipitation and temperature). Community dynamics, nutrient cycle, water cycle, and energy flow are functioning properly. Plant litter is properly distributed with very little movement off-site and natural plant mortality is very low. The diversity in plant species allows for high drought tolerance. Run-off from adjacent sites and moderate or high available water capacity provides a favorable soil-water-plant relationship.
Figure 9. Annual production by plant type (representative values) or group (midpoint values)
Table 5. Annual production by plant type
Shortgrass Cool-Season Community
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 mid-grasses. Blue grama and western wheatgrass are the dominant species with the balance being a few species of cool-season grasses/grass-likes and warm-season grasses including upland sedges, needleandthread, prairie junegrass, and annual grasses. Forbs such as western ragweed, scurfpea, cudweed sagewort and scarlet globemallow may also be present. This plant community can occur throughout the pasture, on spot grazed areas, and around water sources where season-long grazing patterns occur
This plant community is less productive than the Reference Plant Community. Lack of litter and reduced plant vigor result in higher soil temperatures, poor water infiltration rates, and high evapotranspiration, which gives blue grama a competitive advantage over cool-season mid-grasses.
This plant community develops after an extended period of 10 or more years of non-use by herbivores or exclusion of fire. Non-native grasses, such as Kentucky bluegrass, crested wheatgrass, and smooth bromegrass tend to invade and may dominate this plant community. Other grasses present include western wheatgrass, porcupine grass, green needlegrass, and Sandberg bluegrass. The common forbs include sweetclover and cudweed sagewort. Western snowberry and/or silver sagebrush are the principal shrubs and tend to increase in density and cover.
Litter buildup reduces plant vigor and density, and native seedling recruitment declines. Due to a lack of tiller stimulation and sunlight, native bunchgrasses typically develop dead centers and native rhizomatous grasses are limited to small colonies. This plant community is dispersed throughout the pasture, encircling spot grazed areas, and areas distant from water sources. This is a typical pattern found in properly stocked pastures grazed season-long.
This plant community is resistant to change without prescribed grazing or fire. The combination of both grazing and fire is most effective in moving this plant community towards the Reference Plant Community. Soil erosion is low. Runoff is similar to the Reference Plant Community. Once this plant community is reached, time and external resources will be needed to see any recovery in diversity.
Pathway 1.1 to 1.2
Community 1.1 to 1.2
Heavy, continuous grazing and/or continuous seasonal (i.e. spring) grazing will convert this plant community to the 1.2 Blue Grama/Western Wheatgrass Plant Community
Pathway 1.1 to 1.3
Community 1.1 to 1.3
Non-use and no fire for extended periods of time will convert this plant community to the Excessive Litter Plant Community.
Pathway 1.2 to 1.1
Community 1.2 to 1.1
Prescribed grazing that includes changing season of use and allowing adequate recovery periods between grazing events will lead this plant community back to the Green Needlegrass/Western Wheatgrass (Reference Plant Community).
Pathway 1.2 to 1.3
Community 1.2 to 1.3
Non-use and no fire over an extended period of time may lead this plant community to the Excessive Litter Plant Community. This shift may take considerably longer than the corresponding transition from the Reference Plant Community, depending on how much residual cool-season mid-grasses are present upon initiation of non-use or fire exclusion.
Pathway 1.3 to 1.1
Community 1.3 to 1.1
Prescribed grazing or prescribed burning followed by prescribed grazing, will move this plant community toward the Western Wheatgrass/Green Needlegrass Plant Community (Reference). This would require long-term management with prescribed grazing and/or prescribed burning under controlled conditions.
Club Moss State
The Club Moss State is supported by empirical data, historical data, local expertise, and photographs. This state represents a plant community change as well as changes to the energy flow and nutrient cycling processes. This state is defined by one plant community.
Club Moss Community
A dense sod of club moss dominates this plant community. Club moss occupies bare soil areas within deteriorated or disturbed higher successional plant communities due to long-term repeated disturbances. Club moss cover is often 25% or greater. Club moss creates a more arid microclimate, resulting in extreme competition for available moisture. Vigor and production of other species is reduced dramatically.
Grasses and grass-like plants include western wheatgrass, needleandthread, blue grama, prairie junegrass, and upland sedges. Forbs commonly found in this plant community include green sagewort and western yarrow. When compared to the Green Needlegrass/Western Wheatgrass Plant Community, blue grama and club moss have increased, while green needlegrass and western wheatgrass have decreased.
This plant community is very resistant to change. The competitive advantage of both the clubmoss and the blue grama prevents other species from expanding and establishing. This plant community is far less productive than the Reference Plant Community. Initial runoff rates are low but then increase as clubmoss becomes saturated. Once clubmoss has been saturated then runoff increases and infiltration decreases as compared the Reference Plant Community. Soil erosion will be minimal due to the sod forming habit of both the clubmoss and blue grama.
The Annual/Pioneer State is supported by empirical data, historical data, local expertise, and photographs. This state represents a plant community change as well as changes to the energy flow and nutrient cycling processes. This state is defined by one plant community.
This plant community develops under severe disturbance and/or excessive defoliation. This can result from heavy livestock or wildlife concentration, and cropping abandonment (go-back land). The dominant vegetation includes pioneer annual grasses, forbs, invaders, and early successional biennial and perennial species. Grasses may include red threeawn, sixweeks fescue, smooth bromegrass, crested wheatgrass, annual brome, needleandthread, prairie junegrass, and western wheatgrass. The dominant forbs include curlycup gumweed, marestail, salsify, kochia, field bindweed, thistles, western ragweed, pussytoes, prostrate verbena, and other early successional species. Shrubs that may be present include prairie rose, fringed sagewort, and broom snakeweed. Plant species from adjacent ecological sites may become minor components of this plant community. The community is susceptible to invasion of other non-native species due to severe soil disturbances and relatively high percent of bare ground.
This plant community is resistant to change, as long as soil disturbance or severe vegetation defoliation persists, thus holding back secondary plant succession. Soil erosion is potentially high in this vegetation state. Reduced surface cover, low plant density, low plant vigor, loss of root biomass, and soil compaction, all contribute to decreased water infiltration, increased runoff, and accelerated erosion rates.
Significant economic inputs, management and time would be required to move this plant community toward a higher successional stage and a more productive plant community. Secondary succession is highly variable, depending upon availability and diversity of a viable seed bank of higher successional species within the existing plant community and neighboring plant communities. This plant community can be renovated to improve the production capability, but management changes would be needed to maintain the new plant community.
Transition 1.2 to 2
State 1 to 2
Heavy, continuous grazing may cause further deterioration resulting in a shift to the Club Moss Plant Community.
Transition 1 to 3
State 1 to 3
Heavy, continuous grazing, excessive defoliation and/or mechanical tillage may shift this plant community to the Annual/Pioneer Perennial Plant Community.
Restoration pathway 2 to 1
State 2 to 1
Fertilization combined with prescribed grazing may move this plant community through the successional stages leading toward the Green Needlegrass/Western Wheatgrass Plant Community.
Mechanical renovation followed by prescribed grazing will reduce club moss, increase western wheatgrass, and eventually shift this plant community back toward the Green Needlegrass/Western Wheatgrass Plant Community.
Prescribed burning may reduce club moss, and eventually convert this plant community back to the Green Needlegrass/Western Wheatgrass Plant Community.
Restoration pathway 3 to 1
State 3 to 1
Under long-term prescribed grazing and/or removal of disturbance, including adequate rest periods, this plant community will move through the successional stages, and may eventually lead to a plant community resembling the Reference Plant Community. Depending on the slope, aspect, and size, and if adequate perennial plants exist, this change can occur more rapidly. This process will likely take a long period of time (50+ years).