Loamy - North
Scenario model
Current ecosystem state
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Management practices/drivers
Select a transition or restoration pathway
- Transition 1A More details
- Transition 2A More details
- Transition 6A More details
- Transition 2B More details
- Restoration pathway 3A More details
- Transition 6A More details
- Transition 3A More details
- Restoration pathway 4A More details
- Transition 4A More details
- Transition 4B More details
- Restoration pathway 5A More details
- Transition 5A More details
- Transition 6A 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 that dominated the dynamics in 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 and warm season grasses. 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 influences by the presence of non-native cool season grasses, especially Kentucky bluegrass and smooth brome that can dominate the dynamics of this ecological site. Proper grazing management and periodic burning will maintain the productivity of this 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.
Submodel
Description
This state is the result of invasion and dominance of introduced species. This state is characterized by the dominance of Kentucky bluegrass and smooth brome, and an increasing thatch layer that effectively blocks introduction of other plants into the system. Plant litter accumulation tends to favor the more shade tolerant introduced grass species. The nutrient cycle is also impaired, and the result is typically a higher level of nitrogen which also favors the introduced species. Increasing plant litter decreases the amount of sunlight reaching plant crowns thereby shifting competitive advantage to shade tolerant introduced grass 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. Preliminary studies would tend to indicate this threshold may exist when Kentucky bluegrass exceeds 30 percent of the plant community and native grasses represent less than 40 percent 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).
Once the state is well established, even drastic events such as high intensity fires driven by high fuel loads of litter and thatch will not result in more than a very short term reduction of Kentucky bluegrass. These events may reduce the dominance of Kentucky bluegrass, but due to the large amount of rhizomes in the soil there is no opportunity for the native species to establish and dominate before Kentucky bluegrass rebounds and again dominates the system.
Submodel
Description
This state is greatly influenced by conifers, primarily ponderosa pine but rocky mountain juniper can also be present. Ponderosa pine canopy was found to significantly reduce precipitation reaching the forest floor by an average of 30 percent due to interception in area 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
Description
This state is the result of very heavy, concentrated disturbance such as cropping, concentrated rodent activity, or concentrated livestock 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. Extended periods of drought accompanied by 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. Bare ground is also typically much higher than on any other plant community phase.
Submodel
Mechanism
Invasion and/or encroachment of non-native grasses such as Kentucky bluegrass, smooth brome and timothy, and disruption of natural disturbance regimes, typically as a result of fire suppression following settlement led this state over a threshold to the Native/Introduced State 2.0.
Mechanism
Introduction or invasion of non-native cool season grass species. Non-use and no fire. Excessive haying of native grass species and or heavy continuous grazing. This transition is most likely going to occur from PCP 2.2
Mechanism
Encroachment and establishment of conifer trees into this state due to no-use and no fire can cause a transition to the Conifer State.
Mechanism
Severe and frequent defoliation which can be exacerbated by drought and/or additional livestock or wildlife use. Heavy use areas and livestock feeding areas can also cause this transition.
Mechanism
Early season prescribed burning followed by long term prescribed grazing to promote establishment of native species. Chemical and/or mechanical treatment followed by seeding of native species may accelerate the reestablishment 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
Encroachment and establishment of conifer trees into this state due to no-use and no fire can cause a transition to the Conifer State.
Mechanism
Severe and frequent defoliation which can be exacerbated by drought and/or additional livestock or wildlife use will push this plan community to the Early Seral State.
Mechanism
Reintroduction of fire or prescribed burning and/or, mechanical brush management to remove encroachment, followed by long term prescribed grazing to promote reestablishment of native species may accelerated the reestablishment of structural/functional groups similar to PCP 2.1 however the resulting plant community may not achieve management goals.
Mechanism
Wild fire or prescribed burning or brush management to remove conifer encroachment followed by prescribed grazing management will transition back to the Introduced State.
Mechanism
Wild fire, prescribed burn or brush management will treat conifer encroachment on this site but without proper grazing management this state will transition back to the Early Seral State.
Mechanism
Removal of severe grazing disturbance (frequency and intensity), normal precipitation and fire regime, and time. Chemical and/or mechanical treatment followed by seeding of native species may accelerate the reestablishment 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 regime. Chemical and/or mechanical treatment followed by seeding of native and introduced species.
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.