Intermountain Mountain Big Sagebrush Shrubland and Steppe - Natural Community Distribution, DRECP

Intermountain Mountain Big Sagebrush Shrubland and Steppe distribution within the DRECP study area.

This community was extracted from the Land/Use Natural Vegetation Communities dataset provided by Aerial Information Systems and the California Dept. of Fish and Game. Extractions were based on the GroupCommunity field.


The California Department of Fish and Wildlife (CDFW) Vegetation Classification and Mapping Program (VegCAMP) and contractor Aerial Information Systems (AIS) created a fine-scale vegetation map of a portion of the western Mojave Desert in California. The mapped area is bounded to the west and south by USDA Ecoregional Subsection 322Ag of the Mojave Desert (Miles and Goudey 1997). To the east, the portion mapped by AIS (approx. 4,202,000 acres) is bounded by the borders of a vegetation map produced in 2004 for the Mojave Desert Ecosystem Program (MDEP). VegCAMP mapped a portion of the area mapped previously for the MDEP (approx. 776,000 acres) using the finer-scale rules and classification that AIS used for the larger portion (see Figure 1). The boundary of VegCAMP’s study area was chosen to eliminate an arbitrary hole in AIS’s work area based on the MDEP boundary around Ord Mountain, absorb an additional core area for the Mojave Ground Squirrel, include more critical habitat area for the Desert Tortoise, and ensure access to 1-ft. ancillary imagery via ImageConnect©.

The vegetation classification follows Federal Geographic Data Committee (FGDC) and National Vegetation Classification Standards (NVCS). The classification is based on previous survey and classification work including the classification done for MDEP. An additional 98 Rapid Assessment vegetation field surveys were collected in 2011, and some additional mapping classes are based on those unclassified surveys. These classes are considered provisional until better understood (for example, the Ericameria cooperi provisional alliance). See Appendix A for the field form and protocol for the Rapid Assessment surveys.

The map was produced using heads up digitizing on a base of true-color and color infrared 2010 1-meter National Agricultural Imagery Program (NAIP) imagery. Supplemental imagery included Bing mapping services and true-color 1-foot aerial imagery available through GlobeXplorer ImageConnect©. The minimum mapping unit (MMU) is 10 acres; exceptions are made for wetlands and certain wash types (which were mapped to a 1 acre MMU) and areas characterized as human land use polygons (which were mapped to a 2.5 acre MMU).

This report and accompanying data are to be released at the end of June 2012. After this time, a review of AIS polygons and fieldwork will be performed to analyze the percentage of mapped polygons that have had some sort of field assessment related to this project. Additionally, some of the polygons that were mapped to higher levels in the NVCS hierarchy will be re-assessed and assigned to a lower level.