Highland Hills Pine Forest (60+% Slope)

Description

The Reference State represents what is believed to show the natural range of variability that dominated the dynamics of the Mod Steep to Steep Low Mountain Slopes forest ecological site prior to European settlement. Because of the pervasiveness of non-native cool-season grasses and long-term fire suppression in the region, the true Reference State (1.0) does not exist. This description represents the natural range of variability and dynamics under current conditions.

This site in the Reference State (1.0) is dominated by a ponderosa pine overstory, typically with a canopy cover ranging from 30 to 60 percent. The understory consists of shrubs, forbs, and cool-season bunchgrasses and sedges. Predominant shrubs will include common snowberry, bearberry (kinnikinnick), Oregon grape, and russet buffaloberry. Forbs are common and diverse. Dominant cool-season bunchgrasses will include roughleaf ricegrass, bearded wheatgrass, slender wheatgrass, poverty oatgrass, and Rocky Mountain fescue. Sedges will include Hood’s sedge, dryspike sedge, and Richardson’s sedge. Other trees occurring on this site can included quaking aspen, scattered white spruce in the north, and Rocky Mountain juniper in the south.

In pre-European times, the primary disturbance mechanisms for this site in the reference condition included periodic severe drought, episodic insect and disease outbreaks in the ponderosa pine stands, relatively frequent (10 to 20 year interval) low-intensity surface fires, and rare (> 100 year interval) high-intensity stand replacing fires. Severe weather events in the Black Hills are also a significant disturbance that can result in overstory damage and treefall. Severe weather events that are relatively common in the Black Hills are hailstorms, heavy snow fall, ice storms, tornados, and microbursts.

Any of these disturbances, usually in combination, can affect the ponderosa pine overstory and dictate the dynamics that can occur within the natural range of variability of this site. This variability in plant communities can range from old growth forest to early successional shrub and herbaceous plant communities.

Today the primary disturbances are lack of fire, insect and disease, high-intensity fires, severe weather events, wildlife grazing and browsing, and the predominance of non-native cool-season perennial gasses. Some of the steeper slopes (25-30 percent), grazing by cattle will not be a significant disturbance on this site. On less sloping areas livestock grazing and browsing will occur.

Submodel

Description

This state exists as non-native cool season grasses dominate the understory of many sites. The site functions similarly to the reference state and is the most common found condition this site is in today.