Semi-desert Shallowbreaks (Bluebunch wheatgrass/ Utah juniper)
Scenario model
Current ecosystem state
Select a state
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State 2
Utah Juniper/ Wyoming Big Sagebrush/ Depauperate Understory/ Introduced Non-natives State
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Management practices/drivers
Select a transition or restoration pathway
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Transition T1A
The simultaneous introduction of exotic species, both plants and animals, and possible extinctions of native flora and fauna, along with climate change
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Transition T2A
Wildfire
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No transition or restoration pathway between the selected states has been described
Target ecosystem state
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State 2
Utah Juniper/ Wyoming Big Sagebrush/ Depauperate Understory/ Introduced Non-natives State
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Description
The Reference State is a description of the 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 (in the files of the State Range Conservationist) and the familiarity of rangeland relict areas where they exist. The least modified plant community (1.1) would have been a caespitose bluebunch wheatgrass (Pseudoroegneria spicata) dominated grassland with scattered perennial forbs such as buckwheat (Eriogonum spp.), fleabane (Erigeron spp.), beardtongue (Penstemon spp.), locoweed (Astragalus spp.), wild onion (Allium spp.), and western yarrow (Achillea millefolium). Other common grasses would have included needle and thread (Hesperostipa comata), Indian ricegrass (Achnatherum hymenoides), and bluegrasses (Poa spp.) Shrubs such as Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis) and Utah juniper (Juniperus osteosperma) would have been found on the rockiest microsites where fine fuel production was least (1.2) and thus the chances of fires reaching them low (1.1a). With fire, these woody dominated patches would have returned to the grassland-dominated phase (1.2a). A more complete list of species by lifeform for the Reference State is available in the accompanying tables in the “Plant Community Composition by Weight and Percentage” section of this document.
Submodel
State 2
Utah Juniper/ Wyoming Big Sagebrush/ Depauperate Understory/ Introduced Non-natives State
Description
State 2 is a description of the ecological site shortly following Euro-American settlement, and is considered the current potential for this site. This site was heavily utilized by livestock (first by horses and cattle, then later by sheep) almost year around (Parson 1996). Because of the close proximity of these areas to home ranches, livestock were grazed very early in the spring with some feeding and calving/lambing due to the largely southern exposures and excessive drainage to keep the animals out of mud. Especially heavy utilization during the spring quickly led to the loss of bluebunch wheatgrass and other palatable companions such as needle and thread, Indian ricegrass, and the bluegrasses (Stoddart 1940). This heavy grazing diminished the fine fuels, which, along with directed fire suppression, led to the expansion of brush first and later the juniper trees. A small component of introduced annuals were also present, but not yet dominant.
Submodel
Description
This state is dominated by the less palatable woody plants and invasive annuals, mainly cheatgrass (Bromus tectorum), and biennials including tall tumble mustard (Sisymbrium altissimum) and tansy mustard (Descurainia spp.). Because of the steep, rocky character of this site, there are few options available to try and reverse these trends. Simply reducing grazing pressure will only result in a buildup in fuels. The potential for even more noxious plants such as Dyer’s woad (Isatis tinctoria) and knapweed (Centaurea spp.) is high. The prevention of wildfires and limiting grazing can help maintain state resiliency in the phase. Alternatively, recurring fire after a short period of recovery will reduce state resiliency.
Submodel
Mechanism
Transition T1a: from State 1 to State 2 (Reference State to Utah Juniper/ Wyoming Big Sagebrush/ Depauperate Understory/ Introduced Non-natives State)
The simultaneous introduction of exotic species, both plants and animals, and possible extinctions of native flora and fauna, along with climate change, causes State 1 to transition to State 2.
Mechanism
Transition T2a: from State 2 to State 3 (Utah Juniper/ Wyoming Big Sagebrush/ Depauperate Understory/ Introduced Non-natives State to Utah Juniper/ Yellow Rabbitbrush/ Invasive Annuals & Biennials State)
Although the number of livestock, and their timing of use, began to be restricted on BLM land after 1934, heavy utilization by livestock continued on private and state lands. The dominance of woody plants continued to develop. In part due to this increase in browse material, mule deer numbers greatly increased during the 1950 to 1970s. This ESD is a major part of the winter range of mule deer migrating from their summer range in Wyoming to northeast Utah. Despite many special hunts, many deer spend their winters on this ESD. Deer utilize on sagebrush in the winter and native perennial herbs in the early spring. This additional grazing impact pushes the vegetation to State 3. A key indicator of this transition is the build up of fuel. Wildfire will trigger 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.