Loamy - High Central
Scenario model
Current ecosystem state
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Management practices/drivers
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- Transition T1A More details
- Transition T6A More details
- Transition T2A More details
- Transition T6A More details
- Transition T2B More details
- Restoration pathway R3A More details
- Transition T6A More details
- Restoration pathway R4A More details
- Transition T4A More details
- Restoration pathway R5A More details
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No transition or restoration pathway between the selected states has been described
Target ecosystem state
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Description
This state represents what is believed to represent the natural range of variability and plant community dynamics of this ecological site prior to European settlement. The Reference State is unlikely to occur with the introduction of non-native cool-season grasses which are common throughout the MLRA. This site was dominated by cool-season grasses, a diverse forb component and various shrubs. 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 and July. Routine and/or occasional fires reduced tree cover and contributed to the ecological processes that maintained the reference plant community.
Submodel
Description
This state represents what is most typically found on this site. The natural range of variability is influenced by the presence of non-native cool-season grasses, especially Kentucky bluegrass, smooth brome and timothy that can dominate the dynamics of this ecological site.
Preliminary studies indicate when Kentucky bluegrass exceeds 30 percent, and native grasses represent less than 40 percent of the plant community, the plant community crosses a threshold from Native Invaded to Invaded. Plant communities dominated by Kentucky bluegrass have significantly less cover and diversity of native grasses and forb species. (Toledo, D. et al., 2014). Proper grazing management and periodic burning will maintain the productivity of this state. Heavy grazing without adequate recovery, excessive haying, extended periods of non-use, and no fire, can put plant communities at risk of crossing that threshold.
Submodel
Description
This state is the result of invasion and dominance of non-native cool-season grasses - predominantly timothy, Kentucky bluegrass and/or smooth brome. These species will out-compete the native needlegrasses and wheatgrasses and replace them in the plant community. The nutrient cycle is impaired, resulting in a higher level of nitrogen which favors the introduced species. Studies indicate that soil biological activity is altered, and this shift apparently exploits the soil microclimate and encourages growth of the introduced grass species. Once the threshold is crossed, a change in grazing management alone cannot cause a reduction in the invasive grass dominance.
Submodel
Description
This state is the result of very heavy disturbance such as cropping or concentrated livestock feeding areas. This state can develop as a result of invasion by highly competitive weed species such as Canada thistle, hound’s tongue, leafy spurge, or knapweeds. Heavy grazing can also push an at-risk plant community phase to this state. In most cases, this phase is dominated by annual and/or pioneer perennial species. The percentage of bare ground typically is much higher than on any other plant community phase.
Submodel
Description
This state is greatly influenced by conifers: primarily ponderosa pine, but spruce can also be present. The ponderosa pine canopy was found to significantly reduce precipitation reaching the forest floor by an average of 30 percent due to interception in areas of intermediate and dense canopy (Wrage, 1994). This state will develop when conifers encroach onto the site from adjacent forest sites or ecological sites that have been invaded. Encroachment and the establishment of conifers on this site is primarily the result of no fire and grazing management that reduced the competitive nature of the native herbaceous plant community. Once conifers become established on this site, non-native cool-season grasses will increase, especially in the shaded areas.
Submodel
Mechanism
Invasion and/or encroachment of non-native cool-season grasses such as Kentucky bluegrass, smooth brome, and timothy; no use and no fire; continuous season-long grazing or heavy continuous grazing; and/or excessive haying led this state over a threshold to the Native/Introduced State 2.0.
Mechanism
This transition can occur from States 1, 2, 3 to the Early Seral State with heavy disturbance including frequent and severe defoliation, heavy continuous grazing, excessive haying, livestock feeding areas, or cropping.
Mechanism
Continuous season-long grazing, heavy continuous grazing and/or excessive haying, or no use or no fire can cause a transition to a plant community phase that is dominated by non-native cool-season grasses.
Mechanism
This transition can occur from States 1, 2, 3 to the Early Seral State with heavy disturbance including frequent and severe defoliation, heavy continuous grazing, excessive haying, livestock feeding areas, or cropping.
Mechanism
Encroachment of conifers due to no use and or no fire can transition this plant community to a conifer-dominated state.
Mechanism
Mechanical and/or chemical treatment followed by seeding of native cool-season grasses may restore the structural functional groups found in the Native/Introduced State. Subsequent management including long-term prescribed grazing and possibly prescribed burning may in time help to re-establish the plant community phase 2.1, however, management goals may not be achieved. This restoration pathway can take many years and in the end may not be successful.
Mechanism
This transition can occur from States 1, 2, 3 to the Early Seral State with heavy disturbance including frequent and severe defoliation, heavy continuous grazing, excessive haying, livestock feeding areas, or cropping.
Mechanism
Removal of severe grazing disturbance (frequency and intensity), normal precipitation, long-term prescribed grazing, and time. Chemical and/or mechanical treatment followed by seeding of native species may accelerate the re-establishment of structural/functional groups similar to PCP 2.1; however, the resulting plant community may not achieve management goals. This restoration pathway can take many years and in the end may not be successful.
Mechanism
Removal of severe grazing disturbance (frequency and intensity), normal precipitation, and time. Chemical and/or mechanical treatment followed by seeding of introduced forage species for haying and grazing. This resulting plant community will resemble PCP 3.1.
Mechanism
Reintroduction of fire or prescribed burning and/or mechanical brush management to remove encroachment, followed by long term prescribed grazing to promote re-establishment of native species may accelerate the re-establishment of structural/functional groups similar to PCP 2.1; however, the resulting plant community may not achieve management goals.
Model keys
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The Ecosystem Dynamics Interpretive Tool is an information system framework developed by the USDA-ARS Jornada Experimental Range, USDA Natural Resources Conservation Service, and New Mexico State University.