Loamy - South
Scenario model
Current ecosystem state
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Management practices/drivers
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- Transition 1 More details
- Transition 2A More details
- Transition 2B More details
- Transition 2C More details
- Restoration pathway 3A 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
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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 the natural range of variability that dominated the dynamics in this ecological site prior to European settlement. The Reference State does exist currently but with the introduction and spread of non-native cools season grasses it can be difficult to locate in this LRU.
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 typically occurs as a result of the site becoming dominated by non-native cool season grasses, primarily Kentucky bluegrass and/or smooth brome. This can be due to non-use and no fire which creates a large amount of litter, making the site unsuited for native species. Heavy continuous grazing and or mechanical harvesting can also create this state by over utilization of the native grass species, giving a competitive advantage to the non-native species which are adapted to heavy utilization and are grazing resistant. Plant communities dominated by Kentucky bluegrass have significantly less cover and diversity of native grasses and forb species. (Toledo, D. et al., 2014).
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
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
Mechanism
Invasion and/or encroachment of non-native grasses such as Kentucky bluegrass and smooth brome, 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, heavy continuous grazing, or excessive haying of native grass species. This transition is most likely going to occur from PCP 2.2
Mechanism
Severe and frequent defoliation which can be exacerbated by drought, and heavy disturbance areas which can occur around watering sites and livestock feeding areas. This plant community is most likely to transition from PCP 2.3.
Mechanism
Encroachment and establishment of conifer trees due too fire suppression.
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
Severe and frequent defoliation which can be exacerbated by drought, heavy disturbance areas like those around water sources and livestock feeding areas.
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.
Mechanism
Encroachment of conifer trees onto the site due to fire suppression.
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.
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.