Silty 9-12 PZ Snake River Warm Plains

Description

The reference state is representative of the natural range of variability in pristine condition. This is not considered a "historical" condition as examples of this site may still occur across the landscape. This state has no introduced plant species. Disturbance patterns reflect historic return cycles or increased return has not reduced the sites resistance and resilience to disturbance. The reference state has two community phases; a grass shrub community and a perennial grass community. Community dynamics are controlled primarily by fire and time. All functional groups are present and a diverse forb component exists although it is not the dominant component. At the time of this writing, no sites were found in the reference state so community information is inferred from current potential sites and historical data.

Characteristics and indicators

•No introduced plant species
•All functional groups present
•High plant vigor and reproductive capacity

Resilience management

Reference sites should be prioritized for protection whenever possible. Management should focus on conservation and protection above other uses. Surrounding landscapes should be managed to reduce non-native species introductions and other impacts.

Submodel

Description

This state is similar to the refence state but some amount of non-native species occur and species composition has been somewhat altered. Ecological functions often remain intact but due to the presence of these non-native species, resistance and resilience to disturbance has been reduced. This state has three community phases; a grass-shrub phase, a shrub-grass phase, and a grass phase. The latter two representing two different "at-risk" phases, at risk of converting to shrubland and at risk of converting to an annual state.

Characteristics and indicators

•Low cover of introduced plant species (commonly less than fifteen percent total)
•Deep-rooted perennial grass cover at or above twenty percent
•All functional groups present with no significant decrease in reproductive capability

Resilience management

Sites in the current potential state should be prioritized for protection wherever possible, especially when in good quality condition. Management activities should focus on limited seed sources of invasive annual grasses and promote perennial plant vigor and reproduction.

Submodel

Description

This state is dominated by shrubs and shallow-rooted perennial grasses and is a result of over grazing especially during key growth periods of cool-season bunchgrasses. Deep-rooted perennial grass have been reduced or completely excluded rarely exceeding five percent foliar cover. This state consists of two communities, a Wyoming big sagebrush and shallow-rooted grass community, and a shallow-rooted grass community. Although highly variable, invasive annual grass cover is often higher than in the current potential state. Without deep-rooted grasses, this state is more prone to erosion than the current potential state.

Characteristics and indicators

•Typically less than 5% cover deep-rooted perennial grasses.
•High cover of shallow-rooted perennial grass
•Increased invasive annual grass but not enough to become a dominant component.

Resilience management

Management actions should focus on reintroduction of deep-rooted perennial grasses. Invasive annual grass control may also be a priority to avoid transitioning to an annual state.

Submodel

Description

This state is dominated by invasive annual grasses. These grasses increase litter amounts which inhibits deep-rooted perennial grass recruitment and increases fire frequency. These two effects create a positive feedback loop that increases invasive annual grass populations.

Characteristics and indicators

•Annual grass foliar cover greater than 25%
•Sagebrush cover is variable but even when common, interspaces dominated by invasive annual grasses.
•Herbaceous litter cover can be higher than other states

Resilience management

Any management actions should focus on reducing annual grass cover and limiting its spread to other areas.

Submodel