Natural Resources
Conservation Service
Mountain Loam (bigtooth maple)
Scenario model
Current ecosystem state
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Management practices/drivers
Select a transition or restoration pathway
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Transition T1A
introduction of exotic species
More details -
Transition T2A
Sustained heavy grazing
More details -
No transition or restoration pathway between the selected states has been described
Target ecosystem state
Select a state
Description
The Reference State is a description of this ecological site just prior to Euro-American settlement but long after the arrival of Native Americans. The description of the Reference State was determined by NRCS Soil Survey Type Site Location information and the familiarity of rangeland relict areas where they exist. The least modified plant community would have been dominated by bigtooth maple (Acer grandidentatum). Rocky Mountain juniper (Juniperus scopulorum) may also have been a common associate. The understory shrubs would have included mountain big sagebrush (Artemisia tridentata ssp. vaseyana), antelope bitterbrush (Purshia tridentata), and chokecherry (Prunus virginiana). Forbs would have included common yarrow (Achillea millefolium), arrowleaf balsamroot (Balsamorhiza sagittata), sticky purple geranium (Geranium viscosissimum), milkvetch (Astragalus spp.), and buckwheats (Eriogonum spp.), among others. Bluebunch wheatgrass (Pseudoroegneria spicata), basin wildrye (Leymus cinereus), and muttongrass (Poa fendleriana) would have been the dominant grasses (1.1). A more complete list of species by lifeform for the Reference State is available in accompanying tables in the “Plant Community Composition by Weight and Percentage” section of this document.
Submodel
Description
State 2 is a description of the ecological site shortly following Euro-American settlement, which has been influenced by the introduction of several non-native plants and animals, possible extinctions of native species, and a different climate. The plant community will be very similar to State 1 with the exception that some introduced species are likely to be present. The herbaceous species still left in the understory are those more tolerant of grazing pressure and/or are relatively unpalatable to livestock such as Woods’ rose (Rosa woodsii) and mule-ears (Wyethia amplexicaulis). This state has potential of accelerated soil erosion. Where accelerated soil erosion has not yet occurred, the potential for stability in this state is high.
Submodel
Mechanism
The simultaneous introduction of exotic species, both plants and animals, possible extinctions of native flora and fauna, and climate change has caused State 1 to transition to State 2. The advent of heavy continuous season-long grazing by livestock and fire prevention also contributed to this transition. Reversal of such historic changes (i.e. a return pathway) back to State 1 is not practical.
Mechanism
Firewood harvest and/or wildfire will remove the trees while continued heavy livestock grazing during the growing season will further reduce the understory and open it up to introduced non-native species such as cheatgrass (Bromus tectorum) and bulbous bluegrass (Poa bulbosa). A key indicator of the approach to this transition is the reduction of desirable forage and a loss of larger stems of maple. Sustained heavy grazing is the trigger for this transition.
Model keys
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Ecological sites
Major Land Resource Areas
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.
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