Semi-desert Stony Loam (Black sagebrush)

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. Before Euro-American settlement, the Reference plant community (1.1) would have been characterized by scattered black sagebrush (Artemisia nova) and abundant perennial herbs. The major grasses would have included Indian ricegrass (Achnatherum hymenoides) and needle-and-thread (Hesperostipa comata). Primary forbs would have included various buckwheat species (Eriogonum caespitosum, E. microthecum, E. ovalifolium, E. umbellatum), globemallow (Sphaeralcea spp.), and spiny phlox (Phlox hoodii). 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. The productivity would have been relatively higher than the similar, but shallow loamy sites (e.g. 034AY2ppUT Semi-desert Shallow Loam Ecological Site) because of the Inverse Texture Principle (Noy-Meir, 1973). In deserts and semi-deserts, finer textured soils are effectively drier and thus typically have lower production potential than coarser textured soils. The phases of this State would have depended on the time since last fire, starting with a perennial herb-dominated phase (1.1) immediately following fire (1.3a, 1.2b), with yellow rabbitbrush (Chrysothamnus viscidiflorus) becoming temporarily dominant (1.2) approximately 5 to 15 years post fire (1.1a), and finally the re-establishment of black sagebrush (1.3) approximately 20 to 30 years post fire (1.2a).

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 immediately following Euro-American settlement, and is considered the current potential for this site. The phases of this State vary between a native bunchgrass dominated phase (2.1), to a yellow rabbitbrush/ black sagebrush invaded phase (2.2), to a black sagebrush with native perennial understory phase (2.3), which develop according to the time since last wildfire (2.3a or 2.2b, 2.1a, 2.2a, respectively). The resiliency of this state is maintained by the availability of native seed sources for both the herbaceous species and for black sagebrush, and by wildfire. The resiliency of this State can be negatively impacted by heavy livestock and big game grazing.

Submodel

Description

A denser stand of black sagebrush and an understory diminished in palatable herbaceous species (3.1) will be found on sites where continuous season-long grazing by either cattle or big game has taken place. A similar outcome will develop if fire is suppressed. At the higher/moister range of this ESD, juniper (Juniperus osteosperma) and/or pinyon pine (Pinus monophylla in Rich County, Pinus edulis in other parts of this MLRA) may begin to invade the site with continued fire suppression. A return to the Black Sagebrush/ Introduced Non-natives State is possible if the site is grazed during the non-growing season for desirable herbs. Continued heavy livestock and big game use with reduce the resiliency of this State.

Submodel

Description

Very dense black sagebrush and unpalatable forbs are found on sites where heavy continuous season-long grazing and accelerated soil erosion has occurred. Self-armoring of soils will occur when enough rocks are exposed at the soil surface. This self-armored soil surface helps to maintain this state. Continued heavy grazing will reduce the resiliency of this state. At the higher/moister range of this ESD, juniper and/or pinyon pine may invade the site. Mechanical and chemical treatments are not recommended at these sites because the low responses by native perennial herbs after reseeding make them economically inadvisable.

Submodel