Upland Loam (Wyoming Big Sagebrush)

Description

The Reference State includes the plant communities that were best adapted to the unique combination of factors associated with the ecological site. It is assumed that this site was in dynamic equilibrium with the historic biotic, abiotic, climatic factors in North America at the time of European immigration and settlement. This dominant aspect of the plant community is Wyoming big sagebrush and bluebunch wheatgrass. The community is made up of 65 percent grass, 15 percent forbs, and 20 percent shrubs based on dry weight. The community phases are interrelated and dependent on weather patterns and events as well as fire frequency and intensity. The fire frequency should be around 35 to 55 years. Any set of events that force the plant community out of this pattern can push it over a threshold and into another state (i.e. introduction of annual non-native plants).

Characteristics and indicators

This state does not have non-native species in the plant community.

Submodel

Description

The Current Potential State (CPS) includes the biotic communities that would become established on the ecological site if all successional sequences were completed without interferences by humans under the present environmental conditions. Natural disturbances are inherent in its development. The CPS state may include acclimatized, naturalized or invasive nonnative species. There is no known way to effectively remove these plants from the site once they have become established. The level of occurrence of these plants in the CPS is such that careful management can prevent their domination of the site. This site is irreversibly changed. Plant communities within the CPS state may be managed and used for various purposes without significant alteration in plant community composition or production. It includes all the plant communities that exist in the Reference State with the inclusion of species that are non-native to this ESD.

These scenarios are very interrelated and dependent on weather patterns and events as well as fire frequency and intensity. The fire frequency should be around 30 to 55 years. Any set of events that are strong enough to force the plant community out of this pattern can push it over a threshold and push it into another state.

Characteristics and indicators

This state is similar to the Reference State except it includes non-native species in the plant community.

Submodel

Description

The Utah Juniper Invasion State has only two described plant communities, but many variations of the represented ones are present. This state occurs when lack of disturbance, typically fire, has allowed Utah juniper and pinyon to establish and increase on the site. The Utah juniper increases and uses more resources. The juniper will eventually suppresses the shrub and grass understory. Shrubs are typically the first plants to decrease and may be found in small amounts or be absent in the community. The transition to tree dominated increases the probability of non-native annual dominance in the understory as those annual species can utilize the bare space between trees. This state may also accelerate soil erosion as the understory decreases leaving more bare ground susceptible to erosion. This state is persistent until the right conditions occur for a large wildfire. Mechanical tree removal may also occur to reduce tree cover.

Characteristics and indicators

This state will have a noticeable presence of Utah juniper in the plant community.

Submodel

Description

The Yellow rabbitbrush/invasive annuals = native perennials state occurs when fire removes the non-fire tolerant shrubs like big sagebrush. Overgrazing can and often does enhance the effect of fire. Other things like drought can also lead toward this condition. The dominant visual aspect of this community are annual grasses (mainly cheatgrass brome) and yellow rabbitbrush. The plant community composition is 35 percent cheatgrass brome, 10 percent forbs, and 45 percent fire tolerant shrubs with 90 percent of the shrub component being yellow rabbitbrush with 10 percent native perennials. If the site continues along the above described path it will deteriorate to an annual plant community.

Characteristics and indicators

This state is dominated by shrubs other than Wyoming big sagebrush, such as rabbitbrush and broom snakeweed.

Submodel

Description

The Invasive Annual Grass State occurs when this site is overgrazed and then burned and not seeded or has a failed seeding. The dominant aspect of the plant community is cheatgrass brome and yellow rabbitbrush. The community will usually be made up of 75 percent non-native annual grasses, 10 percent forbs (introduced or native), and 10 percent yellow rabbitbrush with minor components of other shrubs. The fire frequency in this state is 4 to 8 years.

Characteristics and indicators

This state will be dominated by invasive annual plants.

Submodel

Description

The Seeded Range State exists when the site is cultivated and/or burned and planted to introduced and/or in some situations native grasses with or with-out forbs and shrubs.

Characteristics and indicators

Non-native bunchgrasses and forbs dominate the plant community.

Submodel