Upland Stony Loam (Utah juniper)
Scenario model
Current ecosystem state
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Management practices/drivers
Select a transition or restoration pathway
-
Transition T1a
introduction of exotic species
More details -
Transition T2a
harvesting for fence posts and firewood and heavy continuous season-long grazing by cattle
More details -
Transition T3a
Wildfire
More details -
No transition or restoration pathway between the selected states has been described
Target ecosystem state
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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 familiarity of rangeland relict areas where they exist. The Reference State for this site would have been a savanna characterized by scattered Utah juniper (Juniperus osteosperma) and a sparse understory of shrubs and low density perennial herbs. 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
Description
State 2 is very similar to State 1 in form and function, with the exception of the presence of non-native plants and animals, possible extinctions of native species, and a different climate. State 2 is a description of the ecological site following Euro-American settlement. Native perennial herbs and shrubs with a scattering of Utah junipers characterize State 2. A small component of introduced species, namely cheatgrass (Bromus tectorum) will also likely be present. This state will maintain resiliency with periodic, light, cool-season fire. Alternatively, heavy grazing and lack of frequent, light, cool-season fires will reduce state resiliency.
Submodel
Description
An expansion of unpalatable shrubs and herbs particularly rabbitbrush (Chrysothamnus spp.) and spineless horsebrush (Tetradymia cansescens), will move into the site if the juniper trees are heavily harvested for firewood and fence posts, and the understory is subject to year-round livestock grazing.
Submodel
Description
Once the site has experienced accelerated soil loss, few species other than juniper and introduced annuals and biennials will be able to grow. With the added impact of fire, this will remove what species were left, making the site available for the re-invasion by Utah juniper.
Submodel
Mechanism
The simultaneous introduction of exotic species, both plants and animals, and possible extinctions of native flora and fauna, along with climate change caused State 1 to transition to State 2. Reversal of such historic changes (i.e. a return pathway) back to State 1 is not practical.
Mechanism
The Utah Juniper/ Introduced Herb State will transition to the Unpalatable Shrub State when the site is exposed to harvesting for fence posts and firewood and heavy continuous season-long grazing by cattle. A key indicator of the approach to this transition is an increase in the size-age growth form of the trees. Human harvest of trees and excessive livestock grazing will trigger this transition. Mechanical, herbicidal, and prescribed burning are not recommended because of slope steepness and potential for soil erosion. A possible restoration pathway would involve reseeding shortly after fire with native grasses and forbs. Trampling in seed with sheep, moved quickly in tight flocks over burned areas, may help seeds germinate.
Mechanism
Wildfire will remove the shrub component as none of the preferred species at the site are likely to re-sprout. Accelerated soil erosion will further limit which species will re-occupy the site, making the site available for re-invasion by Utah juniper and fire-tolerant exotic herbs such as tobacco (Nicotiana spp.), black henbane (Hyoscyamus niger), cheatgrass, Russian thistle (Salsola spp.), and tall thistles (Cirsium spp.). A key indicator of the approach to this transition is an increase in fine fuels, and the trigger is wildfire. As with State 2, mechanical, herbicidal, and prescribed burning are not recommended because of slope steepness and soil erosion potential. A possible restoration pathway involves reseeding quickly with native grasses following fire, and trampling in seed with sheep. Scattered alfalfa hay may be used as an inducement for sheep to trample in reseeded area.
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.