State 1
Reference

Figure 7. Landscape shot of the Foothill Loam site

This state is a mix of grasses and shrubs with some forbs. Natural ecological dynamics from fire, drought, and herbivory cause the shrub density to fluctuate. Where the site has more frags in the profile or texture is a little courser, species such as needleandthread may become more dominant.

Resilience management. The reference state shows the greatest resilience to disturbance. A diversity of plant functional-structural groups create a diversity of root systems which in turn takes in resources and feeds microbial communities. Bare ground is minimal due to a high degree of cover and litter.

Community 1.1
Grass and Shrub Mix

Figure 8. Reference Community: Grass-Shrub Mix

Figure 9. Reference Community in the foreground

This community is grass dominant with a mix of shrubs and forbs. Western wheatgrass is the major grass. Others commonly present are needle and thread, upland/dryland sedges, littleseed ricegrass, and blue grama. There may be small amounts of slender wheatgrass, Scribner needlegrass, muttongrass, Junegrass, squirreltail, Indian ricegrass, sand dropseed, mountain muhly, and Arizona fescue. Forbs are minor with buckwheat, loco weed, and lupine most prevalent. Of the scattered shrubs, fourwing saltbush and rubber rabbitbrush are most common. Others are wax currant, gooseberry, Greene's and Douglas rabbitbrush, winterfat, and skunkbush sumac.

Resilience management. This community is the most resilient to disturbance. Natural disturbance such as fire, drought, and herbivory from multiple classes of fauna, plays a role in maintaining the reference community. Healthy plant and soil dynamics keeps the site populated with a large diversity of plants and root systems which sustains the community through disturbance.

Community 1.2
Shrub Dominant

Figure 12. Shrub Dominant Community

Shrubs show increased cover and production with this community. Common shrubs include: fourwing saltbush, Greene's rabbitbrush, rubber rabbitbrush, skunkbush sumac, wax current, winterfat, and Wyoming big sagebrush.

Resilience management. Shrubs provide cover which captures precipitation. They also have deep taproots to bring up moisture and nutrients which provides resilience during times of drought. As diversity decreases over time so does resilience.

Community 1.3
Warm Season Grass Dominant

Figure 13. Warm Season Grass Dominant

Figure 14. Warm Season Grass Dominant

Figure 15. Warm season grass dominant with rabbitbrush and juniper

This is a warm season dominant community. Blue grama dominates the site. Other species present include purple threeawn, galleta, mat muhly, and sand dropseed. Greene's and rubber rabbitbrush become dominant. Trees are common around this site and are location on shallow soils and/or skeletal soils. Tree species (twoneedle pinyon, oneseed juniper, Rocky Mountain juniper, ponderosa pine and Douglas Fir) may begin to increase and occupy this site. If trees increase they are very minor.

Resilience management. This is considered an "at-risk" community phase. Long-term ecosystem drivers such as extended periods without fire and long-term herbivory targeted on palatable cool season species have created increased woody species, bare ground and erosion. Evergreens such as juniper, which are on the increase in this community can transpire throughout the year adding to the removal of moisture and contributing to droughty conditions. This community can no longer capture and maintain moisture like the community 1.1 and is therefore susceptible to crossing a threshold during an extended drought.

Pathway 1.1A
Community 1.1 to 1.2

Grass and Shrub Mix

Shrub Dominant

Shrubs have slowly gained a competitive advantage due to deeper root systems which have the ability to access moisture and nutrients deeper in the profile than grasses. Extended periods between fire events will help give shrubs a competitive advantage.

Pathway 1.1B
Community 1.1 to 1.3

Grass and Shrub Mix

Warm Season Grass Dominant

The greatest long-term driver is multiple years of grazing throughout the growing season. Preferred palatable species, such as western wheatgrass or needle and thread have less defense mechanisms than blue grama or purple threeawn. Eventually the site manifests itself with short-stature blue grama and increased bare ground. The shrubs have decreased due to disturbance such as fire, disease, excessive browsing, or human treatment.

Pathway 1.2A
Community 1.2 to 1.1

Shrub Dominant

Grass and Shrub Mix

Allowing fire into the system will set back shrubs and invigorate grass species. Other disturbances may be drought, disease, or excessive browsing.

Pathway 1.2B
Community 1.2 to 1.3

Shrub Dominant

Warm Season Grass Dominant

A disturbance, whether human caused or natural to decrease shrubs plus disturbance to decrease the palatable, cool season grasses.

Pathway 1.3A
Community 1.3 to 1.1

Warm Season Grass Dominant

Grass and Shrub Mix

The goal is to reestablish ecosystem diversity and production with attentive grazing management that includes monitoring and adaptive options to focus on cool season species reclamation. An average to above average precipitation year will help with the pathway.

Pathway 1.3B
Community 1.3 to 1.2

Warm Season Grass Dominant

Shrub Dominant

As fire frequency decreases, due to the lack of fine fuels, shrubs may find areas to germinate and grow. Once mature shrubs are established, basal sprouters, such as rabbitbrush, will gain a competitive advantage. Juniper may also increase due to extensive lateral and vertical root systems.

State 2
Degraded Shrub Dominant

Figure 16. Degraded Shrub Dominant

This site is dominated by bare ground and shrub species such as rubber rabbitbrush, Greene's rabbitbrush, and Wyoming big sagebrush. Bare ground is extensive. Warm season grasses are still present.

Resilience management. The site has crossed a threshold to a degraded state. A few resistant shrubs remain while bare ground and erosion is evident. Production and cover are both low.

Community 2.1
Degraded Shrub Dominant

Figure 17. Degraded Shrub State

Figure 18. Extensive bare ground and annuals between shrubs.

The Degraded Shrub Dominant community, at its worse is just a scattering of shrubs and annual forbs with large, continuous areas of bare ground.

Resilience management. Ecosystem health is very low as the site lacks the basic components to capture and maintain moisture. A few shrubs that have developed deep tap root systems remain and help anchor the site.

Community 2.2
Degraded Early Restoration

Figure 19. Western wheatgrass beginning to fill the spaces between shrubs.

Figure 20. Western wheatgrass re-colonizing between shrubs.

Restoration with the degraded shrub state begins with the re-establishment of western wheatgrass, a cool season rhizomatous species that can quickly begin to fill the spaces between shrubs and slow erosion.

Pathway 2.1A
Community 2.1 to 2.2

Degraded Shrub Dominant

Degraded Early Restoration

Re-colonization of western wheatgrass during a good precipitation year.

Pathway 2.2A
Community 2.2 to 2.1

Degraded Early Restoration

Degraded Shrub Dominant

Western wheatgrass has been set back due to drought or excessive herbivory.

State 3
Degraded, Increased Bare Ground

Figure 21. Degraded warm season dominant on convex position

Figure 22. Degraded warm season dominant on linear position

This state has crossed a threshold to a degraded state where bare ground is prevalent and warm season species is dominated by blue grama growing in a sod-forming fashion with low meristems and weak rhizomes. Other warm season grasses that may be present include threeawn and galleta.

Resilience management. Production and cover is low, bare ground and signs of erosion are evident. This state is highly susceptible to drought and further accelerated erosion.

Community 3.1
Degraded, Bare Ground, and Warm Season Dominant

The community has crossed a threshold to a degraded state where bare ground is prevalent and warm season species is dominated by blue grama growing in a sod-forming fashion with low meristems and weak rhizomes. Other warm season grasses that may be present include threeawn and galleta.

Transition T1A
State 1 to 2

Reference

Degraded Shrub Dominant

Slow drivers include a reduced fire regime, often due to the lack of fine fuels; repetitive defoliation and high utilization of palatable species by domestic livestock, especially during drought; and soil destabilizing factors such as erosion.

Transition T1B
State 1 to 3

Reference

Degraded, Increased Bare Ground

Long term drivers such as constant defoliation of preferred species, especially on convex positions which warm up faster in the spring and collect less precipitation in the winter, will degrade toward a bare ground-blue grama dominant site. Blue grama with low meristems and weak rhizomes will persist in these harsher convex areas.

Restoration pathway R2A
State 2 to 1

Degraded Shrub Dominant

Reference

Long term management that improves ecosystem function. This includes restoring soil health and plant diversity. Western wheatgrass is often the first grass to begin recolonization in bare areas, re-establishing a network of rhizomes to begin restoration of site ecological processes. Careful management of grazing plus a possible re-introduction of fire into the systems will be needed for restoring plant and soil health.

Restoration pathway R3A
State 3 to 1

Degraded, Increased Bare Ground

Reference

A long-term management system that monitors and adapts to periodic disturbance such as drought. Establishment of of ground cover, plant diversity, soil organic matter, and aggregate stability is important to re-establishing ecosystem function.