Conservation Assessment of the Tejon Ranch

Executive Summary

January 2004

Tejon Ranch supports a multitude of irreplaceable biological resources, and the melding of these resources in one large, intact landscape makes the Ranch a regionally significant conservation target. Comprehensive land use planning is needed for this keystone property, which is surrounded by growing metropolitan and agricultural areas-the Los Angeles basin, Bakersfield and the San Joaquin Valley, Tehachapi and Cummings valleys in the Tehachapi Mountains, and Antelope Valley of the Mojave Desert. The cumulative effects of conservation and development in this region must be evaluated as part of designing a functional, landscape-scale reserve for Tejon Ranch. Understanding the distribution of conservation values on the Ranch and surrounding areas is critical to inform conservation design for the region. This report evaluates the distribution of conservation values on Tejon Ranch, as an incremental step towards developing a regional reserve design.

We used publicly available data and science-based conservation principles to describe and map selected conservation values for Tejon Ranch. Our assessment demonstrates that, although different areas of the Ranch support different sets of conservation values, virtually all areas of the Ranch support one or more sets of values. To spatially describe the distribution of these values on Tejon Ranch, we identified four landscape units that differentially support the conservation values considered in our analysis:

1. Lowland grasslands and oak savannas of the San Joaquin Valley (108,244 acres)
   • Last remaining connection between grasslands on the east and west sides of the San Joaquin Valley
   • Potential habitat for 5 listed plants, 5 listed animals, and 4 endemic plants considered in this analysis
   • Almost 100,000 acres of grassland and oak savanna communities, which are under-represented regionally in protected open space<
2. Closed-canopy oak woodland, montane hardwood, and montane hardwood-conifer communities on the northwest slope of the Tehachapi Mountains (81,836 acres)
   • Irreplaceable landscape linkage and habitats for foothill and montane species between the Sequoia and Los Padres National Forests
   • 58,000 acres of the highest integrity watershed basins
   • 74,500 acres of the highest diversity of vegetation communities on the Ranch
   • 63,578 acres of roadless areas, including the largest area of roadless habitat >10,000 acres on the Ranch
   • Potential habitat for 3 listed animal species considered in this analysis
3. Oak woodland, chaparral, and pinyon-juniper communities on the southeast slope of the Tehachapi Mountains (26,518 acres)
   • Irreplaceable landscape linkage and habitats for foothill and montane species between the Sequoia and Los Padres National Forests
   • High integrity watershed basins (60% of unit)
   • High diversity of vegetation communities (87% of unit)
   • Over 20,000 acres of roadless areas, including 7,800 acres of roadless habitat >10,000 acres
   • Potential habitat for 2 listed animals and 2 endemic animals considered in this analysis
4. Lowland Joshua tree woodland, grassland, and desert scrub communities of the Mojave Desert (53,613 acres)
   • Landscape linkage and habitats for lowland and desert species
   • Over 25,000 acres of grasslands, which are under-represented regionally in protected open space
   • Over 25,000 acres of roadless habitat (almost half of the unit)
   • Potential habitat for 1 listed animal and 2 endemic animals considered in this analysis

Reserve designs for Tejon Ranch must, at a minimum, capture these values while ensuring the maintenance and management of ecological processes within and between landscape units. Similarly, conservation planning must ensure integration and connection of these landscape units with others in the region, along with a regional plan for long-term management and biological monitoring. Without careful and comprehensive consideration, land use plans for Tejon Ranch could irretrievably alter the biological functions and values of this keystone landscape.