Mojave Desert Vegetation Mapping

In 1996, the USGS Biological Resources Division, at the request of the Department of Defense's Mojave Desert Ecosystem Initiative Legacy Program, began an ambitious project to map vegetation alliances in the California portion of the Mojave Desert, an area of more than 12 million acres.

A collaborative team was established that included researchers from the Geologic Survey, California Department of Fish and Game, and the San Diego State University Department of Geography. The Mojave Vegetation Mapping project is currently being developed under the direction of the Mojave Desert Ecosystem Program (see main article, "Building a Desert Data Clearinghouse") and Desert Managers Group (DMG), a partnership of federal and State resource managers working in the California deserts region.

The project initially established a model-based approach to the mapping of vegetation at the alliance or alliance-complex resolution based on refined California Native Plant Society and National Vegetation classification systems. It was concluded that aerial photography interpretation, combined with the products of predictive modeling, represented the most effective means of developing a geospatial database.

ERDAS and Esri spatial data processing tools were used extensively in the preparation, analysis, and validation of the input and output data sets. The approach utilized desertwide 1:32,000-scale aerial photography using NASA's High Altitude Airborne Science Program. Georectified SPOT satellite imagery was used as base imagery and to adjust for distortion in the aerial photography. During the validation phase, National Aerial Photography Program second-generation digital orthophoto quads (DOQs) have been used in conjunction with fieldwork activities.

This project, intended to produce a digital vegetation map and associated database for the Mojave Desert, is scheduled for completion in the winter of 2000-2001. The database and attending report, when complete, will include eight GIS maps and metadata, a description of vegetation alliances in the Mojave, a plan for accuracy assessment of the vegetation maps, recommendations for procedures to add data to the database, and the project methodology.

For more information, contact Clarence Everly (tel.: 760-256-7033, e-mail: everlyc@mojavedata.gov) or Kathryn Thomas (tel.: 520-556-7466, ext. 235; e-mail: kathryn_a_thomas@usgs.gov).

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