Blue Mountain Foothills, Claypan North 12-16 PZ

Description

The Reference state is representative of the natural range of variability under pristine condition. While occurrence is rare, this is not considered a "Historical" reference since for this ecological site, examples of these conditions may still occur on the landscape. No introduced species occur and repeated disturbance has not fundamentally altered soil quality or plant community composition. The reference state has two general plant communities; a grass-shrub dominant community, a shrub-grass dominant community and a shallow-rooted grass dominant community (considered the at-risk community). State dynamics are maintained by interactions between climatic patterns and disturbance regimes. Negative feedbacks enhance ecosystem resilience and contribute to the stability of the state. These include the presence of all structural and functional groups, low fine fuel loads, and retention of organic matter and nutrients. Plant community changes are primarily driven by fire, time and periodic drought.

Characteristics and indicators

• Lack of introduced plant species
• Presence of all functional and structural groups
• High plant vigor and reproductive capacity in most years
• Lack of widespread soil erosion

Resilience management

Reference sites should be prioritized in landscape health strategies wherever possible. Management should focus on land conservation and protection of these rare conditions above other uses. Surrounding landscapes should be carefully managed to prevent species introductions and other impacts on reference sites. See the "Defend the Core" strategy for additional information (Maestas et al. 2021).

Submodel

Description

This state is similar to the reference state yet some amount of introduced species occur and species composition or soil quality has been altered by long-term overutilization by livestock. Ecological function is largely intact, however the resiliency of the state has been reduced. This state has two general communities; a grass-shrub dominant community, a shrub-grass dominant community and a shallow-rooted grass dominant community (considered an at risk-community). Introduced species may increase in abundance but will not become dominant within this state. Negative feedbacks enhance ecosystem resilience and contribute to the stability of the state. These feedbacks include the presence of all structural and functional groups, low fine fuel loads, and retention of organic matter and nutrients.

Characteristics and indicators

• Low cover of introduced plant species (less than twice as much as deep rooted perennial bunchgrass cover)
• Deep rooted perennial grasses typically greater than 10 percent cover
• Presence of most or all functional and structural groups
• High plant vigor and reproductive capacity in most years
• Lack of widespread soil erosion

Resilience management

Current potential sites in high condition should be prioritized in landscape health strategies wherever possible. Management should focus on protection, minimization of disturbance, and early detection and treatment of plant invasions. Plant community management should focus on preserving deep-rooted perennial bunchgrasses in particular. Surrounding landscapes should be carefully managed to prevent impacts to these sites. See the "Defend the Core" strategy for additional information (Maestas et al. 2021).

Submodel

Description

This state is a product of many years of heavy grazing during growth periods of cool season, perennial bunchgrasses. Much of the deep-rooted perennial bunchgrass component has been lost and cover rarely exceeds 5 to 7 percent. Erosion of part of the surface soil horizon may have occurred and may be ongoing. Sandberg bluegrass will increase with a reduction in deep-rooted perennial bunchgrass competition and become the dominant grass. This state consists of two plant communities, a shallow-rooted bunchgrass dominant community and a little sagebrush, shallow-rooted bunchgrass community. Introduced species cover is typically higher than in the current potential state. The shrub overstory and bluegrass understory dominate site resources such that soil water, nutrient capture, nutrient cycling and soil organic matter are temporally and spatially redistributed.

Characteristics and indicators

• Low cover and production of deep-rooted perennial bunchgrasses (typically less than 7 percent cover)
• Moderate to high cover of shallow-rooted perennial bunchgrasses
• Variable cover of little sagebrush
• Evidence of soil erosion

Resilience management

Management should focus on preserving and reintroducing deep-rooted perennial bunchgrasses and treating introduced annual species to prevent a transition to an annual state.

Submodel

Description

In this state the site has crossed a threshold and is dominated by western juniper. Low sagebrush and perennial bunchgrasses may still be present, but they are no longer controlling site resources. As juniper cover increases, shrub cover typically decreases, therefore this site is characterized by two communities, a western juniper/shrub community and a western juniper dominated community. Soil moisture, soil nutrients and soil organic matter distribution and cycling have been spatially and temporally altered. Soil erosion may accelerate as perennial herbaceous cover decreases.

Characteristics and indicators

• Western juniper canopy cover 10 to 25 percent (or greater) (see Miller et al. 2007 for additional context)
• Deep-rooted perennial bunchgrasses and little sagebrush decreased
• Evidence of soil erosion common

Resilience management

Management should focus on preserving and reintroducing deep-rooted perennial bunchgrasses and treating western juniper to prevent further loss of other plant functional groups. Communities at earlier stages of invasion will have the highest likelihood of restoration success (See Miller et al. 2007). Special care should be taken to avoid removal of old growth western juniper.

Submodel

Description

In this state, the site has crossed a threshold into a state dominated by introduced annual species, especially invasive annual grasses. Invasive annual grasses become increasingly dominant though time by altering nutrient cycling, litter creation, and soil moisture capture thereby promoting positive feedbacks. An increase in fire frequency may also occur due to higher fine fuel loads that become flammable earlier in the season. Shrub and tree cover is variable. Shallow-rooted perennial grasses are common but are no longer controlling site resources.

Characteristics and indicators

• Annual grass cover typically greater than 25 percent
• Deep-rooted perennial grass cover typically less than 5 percent
• Annual grass cover greater than twice as much as deep-rooted perennial grass cover
• Little sagebrush cover may be very low
• Herbaceous litter cover may be abnormally high, especially in summer

Resilience management

Focus management actions on reducing invasive annual grass cover and spread to adjacent sites.

Submodel