Ecological dynamics
Black Hills vegetation types consist of a mixture of forest and grasslands resulting from the varied topography, geology, soils, climate and natural disturbances. Frequent fires, periodic drought, and episodic infestations of mountain pine beetles all contribute to the maintenance of
large, open grasslands scattered throughout the Black Hills. Ponderosa pine is the dominant tree species in the Black Hills. It is a fire-adapted species that coexists with frequent, low-intensity fires that consume small seedlings, prune lower branches from larger trees, and reduce fuel loads.
This site developed under Black Hills climatic conditions with short-term weather variations, light to severe grazing by bison, elk, and small mammals, sporadic natural or man-caused wildfire (often of light intensities), and other biotic and abiotic factors that typically influence soil/site development. The natural fire regime is thought to have helped to maintain this site as a grassland, and the plant communities were free of non-native cool-season grasses.
Grazing, drought and the introduction of non-native cool-season grasses are major drivers that shape this site as well as adjacent ecological sites. It is unclear how critical fire is in maintaining this site as a grassland, but in the absence of fire, some encroachment of ponderosa pine is likely to occur on this site and little bluestem will increase and may become wolfy.
Changes will occur in the plant communities due to short-term weather variations, impacts of native and/or exotic plant and animal species, severe disturbances such as periods of well-below average precipitation, severe defoliation, soil erosion, and no fire and no use. The Channery Loam site can also occur on a wide range of slopes and aspects. The steeper slopes, greater than 20 percent, will tend to have lower total annual production than the slopes of less than 20 percent. The plant communities on the shallower slopes may have slightly more cool-season grasses than those on the steeper slopes. Northern and eastern aspects also may produce a slightly higher percentage of cool-season grasses than south- and west-facing slopes.
The following diagram illustrates the common plant community phases that can occur on the site and the transition pathways between communities. These are the most common plant community phases based on current knowledge and experience, and changes will be made as more data is collected. Narratives following the diagram contain more detail pertaining to the ecological processes.
State 1
Reference State
This state represents what is believed to represent the natural range of variability that dominated the dynamics in this ecological site prior to European settlement. This site is dominated by warm-season grasses. Cool-season grasses are sub-dominant. In pre-European times the primary disturbances included fire, insects and grazing by large ungulates and small mammals. Favorable growing conditions occurred during the spring, and warm months of June through August. Routine and/or occasional fires, remove tree cover and contributed to the ecological processes that maintained the reference plant community. Today a similar state can be found in areas where proper livestock use has occurred and where non-native cool-season grasses have not become well established in the plant communities.
Community 1.1
Little bluestem-Sideoats grama-Big bluestem-Wheatgrass-Needlegrass
Figure 9. Channery Loam - PCP 1.1
Interpretations are based primarily on the Little bluestem-Sideoats grama-Big bluestem-Wheatgrass-Needlegrass/Forb plant community phase. This is also considered to be the Reference or historic plant community. The potential vegetation is about 80 percent grass and grass- like plants, 15 percent forbs, 5 percent shrubs, and 0 to 1 percent trees. Total annual production for a normal growing year is approximately 2,100 lbs./Ac. The community is dominated by warm-season grasses including little bluestem, sideoats grama, big bluestem, and blue and hairy grama. Cool-season grasses and grass-like plants include western and bearded wheatgrass, needleandthread, prairie junegrass, and threadleaf sedge. Forbs are common and diverse. Shrub include prairie rose, leadplant, and fringed sagewort. Conifers may be present, but in very small amounts. This plant community is productive and resilient to disturbances such as drought and fire. It is a sustainable plant community in regard to soil/site stability, watershed function, and biological integrity.
Community 1.2
Little bluestem-Wheatgrass-Blue grama
This plant community phase is the result of continuous season-long grazing without adequate recovery period and no fire. The potential vegetation is about 80 percent grass and grass-like plants, 15 percent forbs, 5 percent shrubs, and 0 to 1 percent trees. Total annual production for a normal growing year is approximately 1,800 lbs./Ac. The community is dominated by little bluestem, blue and hairy grama, and plains muhly. Cool-season grasses and grass-like plants include western and bearded wheatgrass, prairie junegrass, and threadleaf sedge. Forbs are common and diverse, and shrubs include prairie rose and fringed sagewort. This plant community is productive and resilient to disturbances such as drought and fire. It is a sustainable plant community in regard to soil/site stability, watershed function, and biological integrity.
Pathway 1.1A
Community 1.1 to 1.2
Continuous season-long grazing without adequate recovery periods and no fire will cause an increase in little bluestem and short-grass species and upland sedge. Sideoats grama, big bluestem, and needle grasses will decrease but little bluestem and wheatgrasses will persist in the plant community. Lack of fire may also allow conifers to become established, but in relatively small amounts.
Pathway 1.2A
Community 1.2 to 1.1
Prescribed grazing that provides recovery periods after grazing, along with normal precipitation and periodic fire, will allow this plant community to return to the Reference plant community.
State 2
Native/Invaded State
This state represents what is most typically found on this site. It is the result of either the introduction or invasion of Kentucky bluegrass or smooth brome, or no use, or no fire. The natural range of variability is influenced by the presence of non-native cool-season grasses, especially Kentucky bluegrass that can dominate the dynamics of this ecological site. Proper grazing management and periodic burning will maintain the productivity of this state, and it can look very similar to the Reference State. Heavy grazing without adequate recovery, extended periods of drought, or non-use and no fire can put this state at risk of crossing a threshold.
Community 2.1
Little bluestem-Wheatgrass-Needlegrass-Sideoats grama-Bluegrass/Forbs
This plant community phase closely resembles the PCP 1.1; however, non-native cool-season grasses have invaded the site and will persist in the plant community under the current Black Hills climatic conditions. The potential vegetation is about 80 percent grass and grass-like plants, 15 percent forbs, 5 percent shrubs, and 0 to 1 percent trees. Total annual production for a normal growing year is approximately 2,000 lbs./Ac. The community is a mix of warm- and cool-season grasses. The dominant warm-season grasses include little bluestem, sideoats grama, and blue grama. The dominant cool-season grasses include western and bearded wheatgrass, and needleandthread. Kentucky bluegrass and/or other non-native cool-season grasses can make up 2 to 5 percent of the plant community. Forbs are common and diverse. Shrubs include wild rose, leadplant, and fringed sagewort. This plant community is productive and resilient to disturbances such as drought and fire. It is a sustainable plant community in regard to soil/site stability, watershed function, and biological integrity. Management strategies must include techniques that will not cause Kentucky bluegrass and other non-native cool-season grasses to increase significantly, as this could put the plant community at risk of transition to the Introduced/Invaded State (3.0).
Community 2.2
Wheatgrass-Bluegrass-Little bluestem-Blue grama/Forbs
Figure 10. Channery Loam - PCP 2.2
This plant community developed under continuous season-long grazing, continuous seasonal grazing with no change in season of use, heavy continuous grazing, or no use and no fire. This plant community phase is made up of approximately 85 percent grass and grass-like plants, 10 percent forbs, 5 percent shrubs, and 0 to 1 percent trees. The community is dominated by cool-season grasses, with most of the warm-season grass components replaced by Kentucky bluegrass and other non-native cool-season grasses. The dominant cool-season grasses include western and bearded wheatgrass. Kentucky bluegrass or other non-native cool-season grasses can make up 10 to 25 percent of the plant community. Production can be variable, but will typically be less than the PCP 2.1. The period when palatability is high is relatively shorter, as Kentucky bluegrass matures rapidly. This plant community is at risk of crossing a threshold to the Introduced State.
Pathway 2.1A
Community 2.1 to 2.2
Continuous season-long grazing or continuous seasonal grazing occurring at the same time every year, or heavy continuous grazing, and/or no use will cause an increase in non-native cool-season grasses moving this plant community to PCP 2.2.
Pathway 2.2A
Community 2.2 to 2.1
Long-term prescribed grazing that provided adequate recovery and change in season of use, along with normal precipitation regime and prescribed burning may reduce the percentage of non-native cool-season grasses in PCP 2.2 and restore the warm-season grass component typical of PCP 2.1.
State 3
Introduced/Invaded State
This state is the result no use, no fire, or heavy continuous grazing and/or excessive haying, which has allowed Kentucky bluegrass and other non-native cool-season grasses to dominate the site. No use and no fire has caused an excessive thatch layer to develop. Plant litter accumulation tends to favor the more shade-tolerant introduced grass species. The nutrient cycle also is impaired, and the result typically is a higher level of nitrogen which also favors the introduced species. Hydrological function also is impaired as the dense root mats created by Kentucky bluegrass reduces water infiltration. Kentucky bluegrass is very resistant to overgrazing and will expand under heavy continuous grazing and out-compete other native species that are not as adapted to overgrazing.
Community 3.1
Kentucky bluegrass-Wheatgrass-Smooth brome/Green sagewort
Figure 11. Channery Loam - PCP 3.1
This plant community is dominated by Kentucky bluegrass and/or other non-native cool-season grasses (30 percent or more of the PC). This plant community developed under no use and no fire or with heavy continuous grazing. This plant community is made up of approximately 85 percent grasses and grass-like species, 15 percent forbs, and 0-1 percent shrubs. Dominant grasses include Kentucky bluegrass, and smooth brome. Western wheatgrass some needlegrass and blue grama may still be found in the plant community. Forbs commonly found in this plant community include green sagewort and fringed sagewort. Production will be significantly reduced when compared to the interpretive plant community. The period when palatability is high is relatively short, as Kentucky bluegrass matures rapidly. Runoff is high and biological activity in the soil is likely reduced significantly in this phase.
State 4
Clubmoss State
A dense sod of clubmoss dominates this plant community. Clubmoss occupies bare soil areas within deteriorated or disturbed plant communities due to long-term repeated disturbances: its cover is often 25% or greater. Clubmoss alters the normal hydrologic function of this site and creates a more arid microclimate, resulting in extreme competition for available moisture. Vigor and productivity of other native grass species are dramatically reduced.
A restoration or transition pathway from this State to another is unlikely, except on small areas where channers are deeper in the profile. Most areas contain exposed schist channers, and the use of mechanical treatment to break up the clubmoss may not be practical or economical. Herbicides and/or intense short-term hoof action may be effective in reducing clubmoss in the plant community, but the results may be mixed and not meet management goals in the end.
Community 4.1
Club Moss/Blue grama- Bluegrass/Wheatgrass/Sedge/Forbs
Figure 12. Channery Loam - PCP 4.1
Figure 13. Channery Loam - PCP 4.1 - Clubmoss Roots
This plant community is the results of heavy continuous season-long grazing, heavy continuous grazing and/or extended periods of drought. It can transition from any state. The plant community is dominated by dense clubmoss and blue grama however some cool-season grasses and grass-like species, forbs and shrubs will still exist in the plant community. Because of the infiltration is greatly reduced grasses and forbs will lack vigor and production. Cool-season grasses including western wheatgrass, needleandthread, prairie junegrass, bottle-brush squirreltail, threadleaf sedge and bluegrass. Forbs will be common and diverse and include green sagewort and fringed sagewort. This plant community is very resistant to change. The competitive advantage of both the clubmoss and the blue grama prevents other species from expanding and establishing. Initially runoff rates are low but then increase as clubmoss becomes saturated.
Transition 1A
State 1 to 2
Introduction or invasion of non-native cool-season species, or no use and/or no fire will cause a transition from the Reference State to the Native/Invaded State (2.0).
Transition 4A
State 1 to 4
Heavy, continuous, season-long grazing, heavy continuous grazing, heavy disturbance, and/or extended periods of drought can cause this plant community to transition to a Clubmoss State (4.0). This transition can occur from any state.
Transition 2A
State 2 to 3
No use, no fire or heavy continuous grazing and/or excessive haying will cause the Kentucky bluegrass or other non-native cool-season grasses to become dominant in the plant community. Preliminary studies indicate this threshold may exist when Kentucky bluegrass exceeds 30% of the plant community, and native grasses represent less than 40% of the plant community composition. Plant communities dominated by Kentucky bluegrass have significantly less cover and diversity of native grasses and forb species. (Toledo, D. et al., 2014).
This transition is most likely going to occur from PCP 2.2.
Transition 4A
State 2 to 4
Heavy continuous season-long grazing, heavy continuous grazing, heavy disturbance, and/or extended periods of drought can cause this plant community to transition to a Clubmoss State (4.0). This transition can occur from any State.
Transition 3A
State 3 to 2
Early-season prescribed burning followed by long term prescribed grazing to promote establishment of native species may be effective in moving this plant community to the Native/Invaded State (2.0), but it could take years and may not meet management goals.
Chemical and/or mechanical treatment followed by seeding of native species may be possible in some areas where channers are deeper in the soil profile. This could accelerate the reestablishment of structural functional groups similar to those in State 2.0; however, the resulting plant community may not achieve management goals.
Both of these pathway can take many years and may not be successful in the end.
Transition 4A
State 3 to 4
Heavy, continuous season-long grazing, heavy continuous grazing, heavy disturbance, and/or extended periods of drought can cause this plant community to transition to a Clubmoss State (4.0). This transition can occur from any state.
