State 1
Reference

This state represents the natural range of variability that dominates the dynamics of this ecological site (ES). This state is codominated by cool- and warm-season grasses. In pre-European times, the primary disturbance mechanisms for this site in the reference condition included frequent fire and grazing by large herding ungulates. Timing of fires and grazing coupled with weather events dictated the dynamics that occurred within the natural range of variability. Today, this state 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 dominant cool- and warm-season species can decline and a corresponding increase in short-statured species will occur.

Community 1.1
Needlegrass/Bluestem/Western Wheatgrass

Interpretations are based primarily on the Needlegrass/Bluestem/Western Wheatgrass Plant Community Phase (this is also considered to be climax). The potential vegetation is about 80 percent grasses or grass-like plants, 10 percent forbs, 8 percent shrubs, and 2 percent trees. The community is codominated by cool- and warm-season grasses. The major grasses include western wheatgrass, big bluestem, green needlegrass, sideoats grama, and little bluestem. Other grass and grass-like species include needleandthread, porcupine grass, blue grama, buffalograss, and sedges. This plant community is resilient and well adapted to the Northern Great Plains climatic conditions. The diversity in plant species allows for high drought tolerance. This is a sustainable plant community in regards to site/soil stability, watershed function, and biologic integrity.

Community 1.2
Western Wheatgrass/Buffalograss/Grama

This plant community developed under continuous seasonal grazing or from over utilization during extended drought periods. The potential plant community is made up of approximately 83 percent grasses and grass-like species, 10 percent forbs, 5 percent shrubs, and 2 percent trees. Dominant grasses include western wheatgrass, buffalograss, blue grama, and sideoats grama. Grasses of secondary importance include sedge, green needlegrass, Kentucky bluegrass, and tall dropseed. Forbs commonly found in this plant community include cudweed sagewort, goldenrod, and western ragweed. When compared to the Needlegrass/Bluestem/Western Wheatgrass Plant Community Phase (1.1), blue grama and buffalograss have increased. Needlegrasses and tall warm-season grasses have decreased and production has also been reduced. This plant community is moderately resistant to change. The herbaceous species present are well adapted to grazing; however, species composition can be altered through long-term overgrazing. If the herbaceous component is intact, it tends to be resilient if the disturbance is not long-term.

Pathway 1.1a
Community 1.1 to 1.2

Continuous seasonal grazing which includes grazing at moderate to heavy stocking levels at the same time of year each year or a combination of disturbances such as extended periods of below average precipitation coupled with periodic heavy grazing will shift this community to the 1.2 Western Wheatgrass/Buffalograss/Grama Plant Community Phase.

Pathway 1.2a
Community 1.2 to 1.1

Prescribed grazing (alternating season of use and providing adequate recovery periods) or periodic light to moderate grazing possibly including periodic rest will convert this plant community to the 1.1 Needlegrass/Bluestem/Western Wheatgrass Plant Community Phase.

State 2
Shortgrass Sod

Community 2.1
Sedge/Grama/Buffalograss Sod

This plant community evolved under heavy continuous season-long grazing or from over utilization during extended drought periods. The potential plant community is made up of approximately 82 percent grasses and grass-like species, 10 percent forbs, 6 percent shrubs, and 2 percent trees. Dominant grass and grass-like species include sedge, buffalograss, blue grama, and sideoats grama. Grasses of secondary importance include needleandthread, bluegrass, annual bromegrass, and smooth bromegrass. Forbs commonly found in this plant community include cudweed sagewort, goldenrod, and sweet clover. When compared to the Needlegrass/Bluestem/Western Wheatgrass Plant Community Phase (1.1), short-statured species are dominant on this plant community. Tall/mid cool- and warm-season grasses have decreased significantly. This vegetation state is very resistant to change. The herbaceous species present are well adapted to grazing; however, composition can be altered through long-term prescribed grazing. This plant community is less productive than most other phases. The thick sod prevents other species from getting established. Lack of litter and reduced plant vigor causes higher soil temperatures, poor water infiltration rates, and high evapotranspiration which give the short-statured species a competitive advantage. Soil erosion will be minimal due to the sod forming habit of dominant species in this phase.

State 3
Increased Tree Canopy

This state consists of areas where tree canopy increases to a level that impedes the reproductive capability of the major native perennial grass species. The increase in tree canopy is a result of a disruption of the natural historic fire regime that kept the trees at an immature stage.

Community 3.1
Conifer

This plant community develops under non-use, no fire, and encroachment by eastern redcedar, Rocky Mountain juniper, and/or occasionally deciduous trees such as bur oak. These species expand on this site due to suppression of fire. The tree canopy is 15 percent or greater. The potential plant community is made up of approximately 48 percent grasses and grass-like species, 10 percent forbs, 7 percent shrubs, and 35 percent trees. Dominant grasses and grass-likes include western wheatgrass, green needlegrass, Canada wildrye, sideoats grama, little bluestem, and sedges. As the canopy increases, warm-season grasses tend to decrease as the cool-season grasses initially increase. Forbs commonly found in this community include cudweed sagewort, goldenrod, and sweetclover. Nonnative species such as annual bromegrasses and bluegrass will tend to invade. Compared to the Needlegrass/Bluestem/Western Wheatgrass Plant Community Phase (1.1), juniper increases significantly. The grass component decreases dramatically as the buildup of juniper needles increases. Annual herbaceous production also decreases significantly. While the juniper canopy provides excellent protection from the weather for both livestock and wildlife, it is not capable of supporting large numbers of wildlife and livestock due to decreased production. A significant reduction of juniper can be accomplished through timber harvest or crown fire. The vegetation in the understory is capable of enduring fire; however, very hot crown fires will have a detrimental effect to the plant community.

State 4
Invaded

This state is the result of invasion and dominance of introduced species. This state is characterized by the dominance of Kentucky bluegrass and smooth bromegrass and an increasing thatch layer that effectively blocks introduction of other plants into the system. Plant litter accumulation tends to favor the more shade tolerant introduced grass species. The nutrient cycle is also impaired and the result is typically a higher level of nitrogen which also favors the introduced species. Increasing plant litter decreases the amount of sunlight reaching plant crowns thereby shifting competitive advantage to shade tolerant introduced grass species. Studies indicate that soil biological activity is altered, and this shift apparently exploits the soil microclimate and encourages growth of the introduced grass species. Once the threshold is crossed, a change in grazing management alone cannot cause a reduction in the invasive grass dominance. Preliminary studies would tend to indicate this threshold may exist when Kentucky bluegrass exceeds 30 percent of the plant community and native grasses represent less than 40 percent of the plant community composition.

Community 4.1
Smooth Bromegrass/Kentucky Bluegrass

This plant community phase is a result of extended periods of nonuse and no fire. It is characterized by a dominance of smooth bromegrass and Kentucky bluegrass. The dominance is at times so complete that other species are difficult to find on the site. A thick duff layer may also accumulate at or above the soil surface. Nutrient cycling is greatly reduced and native plants have great difficulty becoming established. When dominated by smooth bromegrass, infiltration is moderately reduced and runoff is moderate. Production can be equal to or higher than the interpretive plant community. However, when dominated by Kentucky bluegrass, infiltration is greatly reduced and runoff is high. Production in this case will likely be significantly less. In either case, the period that palatability is high is relatively short, as these cool-season species mature rapidly. Energy capture is also reduced.

Community 4.2
Annual/Pioneer Perennial

This plant community evolved under heavy continuous season-long grazing or from over utilization during extended drought periods. The potential plant community is made up of approximately 50 to 80 percent grasses and grass-like species, 10 to 25 percent forbs, and 5 to 25 percent shrubs and trees. The dominant species are highly variable in this phase, often consisting of invasive species such as annual bromegrass, Kentucky bluegrass, and invasive forbs. Other plant species, from adjacent ecological sites, can become minor components of this plant community. This plant community is susceptible to invasion of Canada thistle and other nonnative species because of the relatively high percent of bare ground. Compared to the Needlegrass/Bluestem/Western Wheatgrass Plant Community Phase (1.1), annual bromegrass, invasive forbs, and percent of bare ground have increased. Western wheatgrass, needlegrasses and other cool-season grasses and grass-like species have decreased as have the warm-season species including big bluestem, sideoats grama, little bluestem, plains muhly, and prairie dropseed. Plant diversity is low (plant richness may be high, but areas are often dominated by a few species). The ecological processes are difficult to restore because of the loss of plant diversity and overall soil disturbance. Soil erosion is potentially very high because of the bare ground and shallow rooted herbaceous plant community. Water runoff will increase and infiltration will decrease due to animal related soil compaction and loss of root mass due to low plant diversity and vigor. This plant community will require significant economic inputs and time to move towards another plant community. This movement is highly variable in its succession. This is due to the loss of diversity (including the loss of the seed bank), within the existing plant community, and the plant communities on adjacent sites. This community can be renovated to improve the production capability, however if management changes are not made the vegetation could revert back to a threeawn/annual community.

Pathway 4.1a
Community 4.1 to 4.2

Heavy continuous seasonal grazing (stocking levels well above carrying capacity for extended portions of the growing season and at the same time of year each year) or heavy continuous season-long grazing will convert this plant community to the 4.2 Annual/Pioneer Perennial Plant Community Phase.

Pathway 4.2a
Community 4.2 to 4.1

Prescribed grazing (alternating season of use and providing adequate recovery periods) or periodic light to moderate grazing possibly including periodic rest will convert this plant community to the 4.1 Smooth Bromegrass/Kentucky Bluegrass Plant Community Phase.

Transition T1b
State 1 to 2

Prescribed grazing (alternating season of use and providing adequate recovery periods) or periodic light to moderate grazing possibly including periodic rest will convert this plant community to the 1.1 Needlegrass/Bluestem/Western Wheatgrass Plant Community Phase.

Transition T1b
State 1 to 3

No fire for extended periods of time will lead the Reference State (State 1) across a threshold resulting in the Increased Tree Canopy State (State 3). This transition also requires the presence of eastern redcedar and/or Rocky Mountain juniper, or other trees that can increase on this site. It is a result of a disruption of the natural historic fire regime that occurred in the past.

Transition T1c
State 1 to 4

Non-use and no fire for extended periods of time (typically for 10 or more years) will likely lead this state over a threshold resulting in the 4.1 Smooth Bromegrass/Kentucky Bluegrass Plant Community Phase within the Invaded State (State 4).

Restoration pathway R2
State 2 to 1

Long-term prescribed grazing (moderate stocking levels coupled with adequate recovery periods, or other grazing systems such as high-density, low-frequency intended to treat specific species dominance, or periodic light to moderate stocking levels possibly including periodic rest) may lead this plant community phase over a threshold to the Reference State (State 1). This will likely take a long period of time, possibly up to 10 years or more, and recovery may not be attainable. Under certain circumstances, the harsh conditions created by the shortgrass sod can lead to the elimination of invasive grass species such as Kentucky bluegrass and smooth bromegrass.

Transition T2
State 2 to 4

Heavy continuous seasonal grazing (stocking levels well above carrying capacity for extended portions of the growing season, and at the same time of year each year, typically beginning early in the season) or heavy continuous season-long grazing will convert this plant community to the 4.2 Annual/Pioneer Perennial Sod Plant Community Phase and the Invaded State (State 4).

Restoration pathway R3
State 3 to 1

Prescribed burning in conjunction with long-term prescribed grazing may lead this plant community across a threshold back to the Reference State (State 1). This would have to take place before the trees reach maturity and are still susceptible to fire and reproductive propagules of the perennial grasses are still present.

Transition T3
State 3 to 4

Wildfire that is intense enough to crown and kill mature trees will cause this plant community to cross a threshold and lead to the Invaded State (State 4) and specifically to the Annual/Pioneer Perennial Plant Community Phase (4.2).

Restoration pathway R4
State 4 to 1

Long-term prescribed grazing (moderate stocking levels coupled with adequate recovery periods, or other grazing systems such as high-density, low-frequency intended to treat specific species dominance, or periodic light to moderate stocking levels possibly including periodic rest) may lead this plant community phase over a threshold to the Reference State (State 1). This will likely take a long period of time, possibly up to 10 years or more, and recovery may not be attainable. Success depends on whether native reproductive propagules remain intact on the site.

Restoration pathway R4
State 4 to 1

Long-term prescribed grazing (moderate stocking levels coupled with adequate recovery periods, or other grazing systems such as high-density, low-frequency intended to treat specific species dominance, or periodic light to moderate stocking levels possibly including periodic rest) may lead this plant community phase over a threshold to the Reference State (State 1). This will likely take a long period of time, possibly up to 10 years or more, and recovery may not be attainable. Depending on the slope, aspect, and size, and if adequate perennial plants exist, this change can occur more rapidly.