Steep-Sided Wooded Draw

Description

This state represents the natural range of variability that dominated the dynamics of this ecological site prior to European influence. The primary disturbance mechanisms for this site in the reference condition included droughts of varying length and severity, soil slumping, ground fires, and wildlife trailing. The timing of fires coupled with weather patterns dictated the dynamics that occur within the natural range of variability. These factors likely caused the community to shift both spatially and temporally between three community phases.

This state was dominated by an overstory of green ash with a shrub understory of chokecherry and American plum. The herbaceous understory was dominated by sedges (e.g., Sprengel’s sedge) with lesser amounts of shade-tolerant grasses, such as littleseed ricegrass. Common forbs included northern bedstraw, starry false lily of the valley, and meadow-rue. Bare ground was less than one percent due to a dense plant canopy and leaf litter. Rocky Mountain juniper may have been present as scattered, mature trees.

Characteristics and indicators

Because of changes in disturbances and other environmental factors (particularly the widespread occurrence of exotic species), the Reference State is considered to no longer exist.

Resilience management

If intact, the reference state should probably be managed with current disturbance regimes which has permitted the site to remain in reference condition as well as maintaining the quality and integrity of associated ecological sites. Maintenance of the reference condition is contingent upon a monitoring protocol to guide management.

Submodel

Description

This state is similar to State 1: Reference State but has now been colonized by the exotic cool-season grasses (e.g., Kentucky bluegrass, smooth brome) which are now present in small amounts. Although the state is still dominated by native trees and shrubs, exotic cool-season grasses have increased in the understory. These exotic cool-season grasses can be quite invasive and are particularly well adapted to heavy grazing, shading, as well as long-term non-use. These exotic cool-season grasses have been particularly and consistently invasive under extended periods of no fire. To slow or limit the invasion of these exotic grasses, it is imperative that managerial techniques (e.g., prescribed grazing, prescribed burning, and/or mechanical treatment (juniper removal)) be carefully constructed, monitored, and evaluated with respect to that objective. If management does not include measures to control or reduce these exotic cool-season grasses, the transition to State 3: Invaded State should be expected.

The invasion of Rocky Mountain Juniper within State 2 occurs when a juniper seed source is present. Lack of active juniper management will lead to State 4.0 Conifer Invaded State. Active management includes prescribed burning and mechanical juniper removal. Limiting juniper seed sources is important to avoid re- invasion of juniper on the site. Active monitoring and management are needed to remove new juniper seedlings as they establish from seedbanks or dispersal.

Other exotic plants invading the site include Canada thistle, leafy spurge, hounds tongue, and common burdock. Rocky Mountain juniper, creeping juniper, and perhaps eastern red cedar may also invade the site. Annual production of this state can be quite variable, in large part due to variations in shading and the amount of exotic cool-season grasses.

Characteristics and indicators

The presence of trace amounts of exotic cool-season grass species indicates a transition from State 1 to State 2. The presence of exotic biennial or perennial leguminous forbs (i.e., sweet clover, black medic) may not, on their own, indicate a transition from State 1 to State 2 but may facilitate that transition.

Resilience management

To slow or limit the invasion of these exotic cool-season grasses, it is imperative that managerial techniques (e.g., prescribed grazing, prescribed burning) be carefully constructed, monitored, and evaluated with respect to that objective.

Due to site conditions (e.g., steep slopes, limited forage production, etc.) grazing on this site is limited. Slopes range from 9 to 70% generally limits grazing on these steeper slopes. Livestock trailing can occur especially when close to a water source. Therefore, grazing management efforts should be concentrated on adjacent sites and should be applied that enhances the competitive advantage of native grass and forb species. This may include: (1) grazing when exotic cool-season grasses are actively growing, and native cool-season grasses are dormant; (2) applying proper deferment periods allowing native grasses to recover and maintain or improve vigor; (3) incorporating early heavy spring utilization which focuses grazing pressure on exotic cool-season grasses and reduces plant litter provided that livestock are moved when grazing selection shifts from exotic cool-season grasses to native grasses.

Submodel

Description

This state often develops in association with heavy continuous grazing on adjacent sites, or where livestock activity significantly impacts the woody vegetation. It can be characterized by scattered mature and decadent green ash, in association with chokecherry and an understory predominantly consisting of exotic herbaceous species. Exotic cool-season grasses often include Kentucky bluegrass, smooth brome, and/or crested wheatgrass. Exotic forbs (such as leafy spurge, Canada thistle, and hound’s tongue) may also be present.

Characteristics and indicators

This site is characterized by exotic herbaceous species constituting greater than 30 percent of the annual production and native herbaceous species constituting less than 40 percent of the annual production.

Resilience management

Applying grazing management to adjacent sites which incorporates adequate deferment periods between grazing events and proper stocking rate levels will help maintain this State. The application of herbaceous weed treatment may be needed to manage noxious weeds.

Submodel

Description

This state results from extended periods of no fire, often in association with long-term non-use or very light grazing. It is characterized by the dominance of conifers, such as Rocky Mountain juniper or ponderosa pine, which may have been present as scattered, mature trees prior to European influence. However, since that time a marked decrease in fire frequency and increased fire suppression has been particularly important in enabling conifers to increase and dominate the site. Associated plants can be quite variable in composition and production depending upon juniper age, size, density, and other factors.

Characteristics and indicators

The dominance of conifers in association with an herbaceous understory composed largely of exotic cool-season grasses distinguishes this state from other states.

Resilience management

This state is resistant to change in the long-term absence of fire. Restoration efforts would require the use of prescribed fire, mechanical treatment, and prescribed grazing. Considerable time and effort will be required to restore to other States.

Submodel