Vegetation - Mecca Hills and Orocopia Mountains [ds2692]

The University of California, Riverside Center for Conservation Biology (CCB) created a fine scale vegetation map of the Mecca Hills and Orocopia Mountains Conservation Area in the Coachella Valley of Riverside County, California covers approximately 112,775 acres. This map and report were prepared for the Coachella Valley Multiple Species Habitat Conservation Plan (MSHCP) under contract with the Coachella Valley Conservation Commission (CVCC). The Mecca Hills and Orocopia Mountains final vegetation map, ecological descriptions, classification, and report, were completed in 2015. Initial mapping began with photo-interpretation and field work in 2013 and 2014, with additional work continuing until 2015. One hundred eighty-six reconnaissance vegetation assessment plots were conducted within the study area. Photo-interpretation of 2013 imagery was completed in October 2015 and match the most recent vegetation classification presented in the Manual of California Vegetation Second Edition (Sawyer et al. 2009). Thus, the current version of the map best represents the status of vegetation in 2013.

The vegetation classification follows Federal Geographic Data Committee (FGDC) and National Vegetation Classification Standards (NVCS; Federal Geographic Data Committee 2008). The classification is based on previous survey and classification work done by California Department of Fish and Wildlife's Vegetation Classification and Mapping Program (VegCaMP) and Aerial Information Systems (AIS) for the Desert Renewable Energy Conservation Plan, and by the National Park Service for Joshua Tree National Park. This unit was mapped using the California Department of Fish and Wildlife (CDFW) and California Natural Plant Society Combined (CNPS) Vegetation Classification and Mapping Program protocol (CNPS 2011, 2014). The primary purpose was to develop a dynamic and accurate vegetation map for the Coachella Valley Mecca Hills and Orocopia Mountains Conservation Area, so that it may be applied to future conservation efforts, and assist with management of the 27 species and 27 natural communities listed within the plan . The map was produced by applying heads up digitizing techniques using a base of true color and color infrared 2013 six-inch imagery from the National Agricultural Imagery Program (NAIP) and local flights provided by the Coachella Valley Conservation Commission. Map polygons were assessed for vegetation type, percent cover, presence of exotics, anthropogenic disturbance, and roadedness.

This, the current version of the vegetation classification for the Mecca Hills and Orocopia Mountains Conservation Area of the Coachella Valley MSHCP includes 1,149 polygons with 24 Alliances and 65 Associations. Alliances were assigned for all polygons, and the additional Association attribute was assigned where field plot data (Vegetation Assessment plot) was available within the polygon boundaries. This unit has two map classes that have less than 2% absolute vegetation cover, including Disturbed/Built-Up, a generic Non-Vegetated Habitat type. The largest amount of land cover is of the Non-Vegetated Habitat type, encompassing 69,600 acres (28,200 ha). Of the alliances within the vegetated areas, the largest amount of vegetation area is classified under the Larrea tridentate-Encelia farinosa Shrubland Alliance. This Alliance covers a total of 12,730 acres (5152 ha), representing 11.3% of the total area within the map. For most alliances occurring in expansive areas, a minimum mapping unit of 2.47 acres (1 ha) was observed. To better focus on conservation of particular habitats, there are several alliances where the minimum mapping unit (MMU) is less than an acre; including Prosopis glandulosa Woodland Alliance, Xylorhiza cognata Provisional Alliance (MMU 0.3 acres and MMU 0 .5 acres, respectively), and Washingtonia filifera Shrubland Alliance (MMU 0 .34 acres), as well as wetlands and certain wash types which displayed complexity that would necessitate delineation. This report and accompanying data are to be released at the end of 2015. Periodically, a review of the original polygons and fieldwork will be performed to update the map and determine change across the landscape.

The Mecca Hills and Orocopia Mountains Vegetation Map Report is available for download here: http://nrm.dfg.ca.gov/FileHandler.ashx?DocumentID=138028 .

CDFW appreciates learning how our datasets are being used so that we can leverage support for classifying and mapping new areas and let users know of any updates. Please contact Diana Hickson by email Diana.Hickson@wildlife.ca.gove or by phone at (916) 327-5956.