State 1
Reference

Figure 8. Reference State: Diverse warm season grasses and shrubs

The reference state has an abundance of tall warm season grasses with a mix of shrubs and forbs. Community phases capture the ebb and flow of shrubs and grasses due to disturbance and time.

Community 1.1
Warm Season Grasses and Shrub Mix

Figure 9. West of Villa Grove

This community phase evolved with grazing by herbivores such as bison and elk and is well suited for grazing by wildlife and livestock. It can be found on areas that are carefully managed to allow palatable species an opportunity to grow, colonize, and produce annual root stock. . Principle dominant plants include: alkali sacaton, alkali wildrye, and alkali cordgrass. Grasses of secondary importance include: western wheatgrass, inland saltgrass, and blue grama. Key forbs and shrubs include: American licorice, scarlet globemallow, black greasewood and rubber rabbitbrush. Secondary shrubs such as fourwing saltbush and Greene’s rabbitbrush are present but not significant. Forbs are sparse. The reference community phase structural/functional composition is about 70% grasses and grass-likes, 5% forbs, and 25% shrubs. This community phase is stable and productive. Litter is properly distributed with very little movement off-site and natural plant mortality is low. Slick spots (bare exposed areas, high in sodium) are an inherent characteristic occupying less than 3% of the community. This is a sustainable plant community in terms of soil stability, watershed function, and biological integrity.

Resilience management. This community phase shows the highest resilience to disturbance. A diversity of root systems, cover, and stable soil act as a hedge to drought and disease.

Community 1.2
Low Stature Warm Season Grass and Increased Rabbitbrush

Figure 12. South of Saguache

This is an "at risk" community phase where palatable species such as alkali sacataon and alkali wildrye have decreased, and lesser palatable species such as inland saltgrass and rubber rabbitbrush have increased. Inland saltgrass has increased, and with its dense root system dominates the community. Rubber rabbitbrush is increasing in abundance. Alkali sacaton, alkali cordgrass, western wheatgrass, and alkali wildrye have been significantly reduced. Forbs are still present in reduced amounts. Greasewood is beginning to be hedged while fourwing saltbush decreases in abundance. This plant community is at risk of losing key warm and cool season grasses, palatable forbs, and shrubs. The plants within this community have decreased in frequency and production. Less litter can be expected, however the soil remains stable.

Resilience management. As inland saltgrass becomes more dominant, there is greater resistance of movement toward the reference community phase and the site is more prone to cross a threshold.

Community 1.3
Excessive Plant Litter and Low Plant Density

Increased Plant Litter, Low Plant Density, High Vigor Greasewood Plant Community This plant community occurs when livestock is removed for long periods of time in the absence of fire. Plant composition is similar to reference, however individual species production and density will be lower. High vigor black greasewood is an obvious indicator of non-use. Much of the nutrients are tied up in excessive litter. The semiarid environment and the absence of animal traffic to break down litter slow nutrient cycling. Aboveground litter also limits sunlight from reaching plant crowns. Many plants, especially bunchgrasses die off under these condtions. A thick mat of litter along with absence of grazing animals (animal impact) or fire reduce seed germination and establishment. In advanced stages, plant mortality can increase and erosion may eventually occur if bare ground increases. Once this happens it will require increased energy input in terms of practice cost and management to move back toward reference. .

Pathway 1.1A
Community 1.1 to 1.2

Warm Season Grasses and Shrub Mix

Low Stature Warm Season Grass and Increased Rabbitbrush

Repetitive defoliation with high utilization of palatable species throughout the growing season will eventually weaken vigor and density and lead toward a shift to species that have greater defenses or adaptability toward grazing.

Pathway 1.1B
Community 1.1 to 1.3

Non-use (rest) or absence of fire will alter this plant community to one where litter build-up decreases sunlight to the crown and slows annual bud initiation. These decreases basal density and ultimately decreases nutrient cycling for the site.

Pathway 1.2A
Community 1.2 to 1.1

Low Stature Warm Season Grass and Increased Rabbitbrush

Warm Season Grasses and Shrub Mix

A change in livestock management where palatable species have an opportunity to grow, set seed, and re-colonize. This coupled with an average to above average moisture season will help the site to recover.

Pathway 1.3A
Community 1.3 to 1.1

Resuming livestock management with careful monitoring of litter and species composition along with adaptive management will help the management process.

State 2
Disturbed

Community 2.1
Saltgrass, Rabbitbrush, and Hedged Greasewood

Figure 14. Disturbed: saltgrass-rabbitbrush-hedged greasewood community

This state is dominated by Inland Saltgrass, Rubber Rabbitbrush, and “Hedged” Greasewood with Increased Bare Ground and Slick Spots. Inland saltgrass and rubber rabbitbrush have increased while the greasewood has taken on a hedged appearance through heavy browsing. Bare ground has increased as well as slick spots (bare high sodium areas). Most, if not all, of the reference state grasses have been eliminated. Annuals such as kochia, lambsquarters, Russian thistle, tansy mustard, and pepperweed have invaded the community. Compared with production at reference conditions, perennial species diversity, and frequency has been significantly reduced. Litter amounts are low due to the loss of perennial production. Bare ground is obvious and erosion is a concern. Water and nutrient cycles are impaired. Reduction of mid cool and warm season bunch grasses, and dominance of warm season short rhizomatous grass has altered the biotic integrity of this community.

State 3
Degraded

Community 3.1
Decadent Greasewood with Sparce Understory

Figure 15. Degraded Decadent Greasewood, with little to no understory

The community is dominated by decadent greasewood with remnant inland saltgrass and rubber rabbitbrush. Slick spots and bare ground exist at previous levels or have increased slightly. Soil crusts are eminent and plant germination has all but ceased. This community is in a state of suspended animation. Decadence and mortality are evident. Hydrologic cycle and nutrient cycles have shut down. The semiarid environment, alkalinity, and the absence of animal traffic to break soil crusts and incorporate litter keep this community at a stand still. There is no practical means for restoring reference condition.

State 4
Irrigation Water Influenced

Community 4.1
Irrigation Water Influenced

Baltic rush and inland saltgrass is common. Rubber rabbitbrush remains scattered. Foxtail barley, poverty weed, and alkali muhly will increase in abundance. Invasive perennials that could be present are Swainson pea, Russian knapweed, and whitetop. This state is patchy with alkali sacaton and shrubs still present on the high ground and minimal vegetation throughout the low ground.

Transition T1A
State 1 to 2

This threshold was crossed as long-term repetitive defoliation at high utilization of palatable species have led a loss of bunch grasses and greasewood has lost vigor. Inland saltgrass and rubber rabbitbrush have increased while greasewood has taken on a hedged appearance through heavy browsing. Bare ground has increased as well as slick spots (bare high sodium areas). Most, if not all, of the reference grasses have been eliminated.

Transition T1B
State 1 to 4

Introduction of irrigation water on this site, produces a plant community dominated by rushes and sedges. Greasewood and alkali sacaton will disappear from lower areas and reside on higher ground.

Restoration pathway R2A
State 2 to 1

If livestock grazing is re-instituted, very long-term, careful livestock management with adequate recovery opportunities for key species, especially alkali sacaton along with low to moderate utilization will slowly shift this plant community toward the Increased saltgrass and rubber rabbitbrush; community phase within the reference state. This is a slow process and may take upward of 80 years or more to achieve. Monitoring trend in species composition along with applying adaptive management is important.

Transition T2A
State 2 to 3

This site started as the hedged state, then livestock is removed due to little forage availability. There is not enough fuel to carry a fire and the greasewood becomes decadent. There is no practical means of reversing the transition. Excessive soil erosion has increased the area of high clay and salty slick spots making plant colonization extremely difficult.

Restoration pathway R4A
State 4 to 1

Non-irrigation and time for re-colonization of species. If livestock grazing is re-implemented then careful grazing management will eventually shift this community back to the reference state. The seed source is still present on higher ground and should begin to colonize the lower areas. Monitoring of key species is important for success.