High Mountain Loam (mountain big sagebrush)
Scenario model
Current ecosystem state
Select a state
Management practices/drivers
Select a transition or restoration pathway
-
Transition T1a
introduction of exotic species
More details -
Transition T2a
Heavy continuous season-long grazing
More details -
Transition T3a
Brush management by chemical means
More details -
Transition T3b
Brush management by prescribed fire combined with a period of grazing deferment
More details -
Transition T3c
On gentler slopes, some locations may be plowed and seeded
More details -
Transition T4a
Heavy, continuous, season-long grazing
More details -
Transition T5a
Heavy, continuous, season-long grazing
More details -
Transition T6a
Heavy, continuous, season-long 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 familiarity with rangeland relict areas where they exist. The pre-settlement vegetation here would have varied from a herbland (1.1) to a shrub steppe (1.2) primarily depending on when a wildfire last occurred. Dominant shrubs would have included mountain big sagebrush (Artemisia tridentata ssp. vaseyana) and mountain snowberry (Symphoricarpos oreophilus) with an understory of native perennial grasses such as slender wheatgrass (Elymus trachycaulus), mountain brome (Bromus marginatus), Columbia needlegrass (Achnatherum nelsonii), sheep fescue (Festuca ovina), and oniongrass (Melica bulbosa). The forb component would have included sticky purple geranium (Geranium viscosissimum), Nevada pea (Lathyrus lanszwertii), and buckwheats (Eriogonum spp.) among several others. The driving factor behind changes in relative abundance and shrubs and the associated understory would have been time since last fire event. An herbaceous understory with only a minor amount of shrubs (1.1) would have been found following a recent wildfire (1.2a). Shrubs would have increased, crowding out herbaceous understory (1.2) as the time since the last fire lengthened (1.1a). A fire return of interval of 25 to 35 years was probable. 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 ESD 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 some native species, and a different climate. State 2 is a description of the ecological site shortly following Euro-American settlement. This sagebrush steppe, including some exotics, should be considered the current potential. Like the Reference State, the length of time elapsed since the last fire would have influenced the relative abundances of shrubs and herbs in this State.
Submodel
Description
Effects from heavy continuous season-long livestock grazing include an increase in shrub canopy and reduction in herbaceous understory components. If accelerated soil erosion has ensued, introduced species are favored because of xerification and eutrophication of the site. Excessive grazing and fire exclusion will reduce the stability of this state. Moderating the grazing will allow fire to resume its role and diversify the vegetation.
Submodel
Description
As a result of brush management by chemical means, the site will become grass-dominated. Forbs and shrubs will have a minor presence. Grasses will include slender wheatgrass, mountain brome, Columbia fescue and Letterman’s needlegrass.
Submodel
Description
As a result of brush management by fire, this site will become dominated by a mixture of grasses and forbs. Shrubs will constitute a minor component.
Submodel
Description
On more gentle slopes, where plowing and seeding is feasible, slender wheatgrass or mountain brome can be seeded. If introduced grasses such as intermediate wheatgrass, orchardgrass, and smooth brome have already been seeded, then these aggressive exotic grasses will dominate. In recent trials, native grasses have been planted much more successfully.
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. Reversal of such historic changes (i.e. a return pathway) back to State 1 is not practical.
Mechanism
Heavy continuous season-long grazing (which was prevalent between the 1860s and 1950s), will cause State 2 to transition to State 3.
Mechanism
Brush management by chemical means (2,4-D, tebuthiron) will reduce the shrub component.
Mechanism
Brush management by prescribed fire combined with a period of grazing deferment will reduce fire-intolerant shrub species and allow the herbaceous component and native grasses to re-establish.
Mechanism
On gentler slopes, some locations may be plowed and seeded with native mountain brome or slender wheatgrass. In the past intermediate wheatgrass (Thinopyrum intermedium), orchardgrass (Dactylis glomerata), or smooth brome (Bromus inermis) has been planted, but establishment of native species will have greater success.
Mechanism
Heavy, continuous, season-long grazing will return State 4 to State 3, a mountain big sagebrush dominated state.
Mechanism
Heavy, continuous, season-long grazing will return State 5 to State 3, a mountain big sagebrush dominated state.
Model keys
Briefcase
Add ecological sites and Major Land Resource Areas to your briefcase by clicking on the briefcase (
) icon wherever it occurs. Drag and drop items to reorder. Cookies are used to store briefcase items between browsing sessions. Because of this, the number of items that can be added to your briefcase is limited, and briefcase items added on one device and browser cannot be accessed from another device or browser. Users who do not wish to place cookies on their devices should not use the briefcase tool. Briefcase cookies serve no other purpose than described here and are deleted whenever browsing history is cleared.
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.