Center for Conservation Biology

California deserts are faced with unprecedented anthropogenic change. Impact factors range from expanding urban centers and military bases, to potential significant habitat loss from solar and thermal power expansions (including ground water exploitation and depletion beyond recovery, land stripping for power generation units, and fragmentation from power and associated transportation corridors), and climate change. Together these factors threaten remaining suitable habitat for endangered and for other endemic desert species. Our goal here is to outline the scope of environmental changes that are underway, and to outline research needs necessary to provide long-term sustainability of federally- and state-listed species and their habitats, ensuring that energy developments are also fully compliant with the letter and intent of state and federal resource protection statutes. We identified several topic areas that are of concern to land managers and project developers in the California deserts. These represent topic areas badly in need of research using state-of-the-art techniques coupled with known expertise, tailored to the desert areas to be impacted by the proposed developments.

The goal of this research contract was to provide Caltrans with niche models for the assessment of the conservation potential of lands within the delineated Criteria Areas of the Western Riverside County Multiple Species Habitat Conservation Plan (WRC MSHCP). Caltrans could then use these results to prioritize lands for further evaluation and potential acquisition in order to meet their Implementing Agreement commitments under the WRC MSHCP.

In 2002, the Center for Conservation Biology (CCB) of the University of California at Riverside initiated a multi-year collaboration with the Coachella Valley Association of Governments to develop a monitoring framework for the Coachella Valley Multiple Species Habitat Conservation Plan (CV MSHCP) (see Allen et al 2005). This final report reflects the findings for the 2005-2006 project period (September 1, 2005 – December 31, 2006), undertaken by the CCB’s Desert Studies Initiative, to initiate an analysis of the impacts of the exotic weed, Saharan mustard (Brassica tournefortii) with regard to the conservation goals of the CV MSHCP. 2005 marked the most severe outbreak of Saharan mustard in more than a decade. Concern over the impacts of this weed not only with regard to the CV MSHCP, but in the entire southwestern desert region was the impetus for initiating this research. In particular, the questions addressed were the following, and are answered in the next section:

• What variables best predict the occurrence and density of this weed species?

• Does anthropogenic nitrogen deposition influence its distribution and density?

• Is the extent of the weed infestations expanding, or is it an oscillation in response to the pattern and amount of precipitation?

• What are the impacts of the exotic plants on the aeolian sand community? Are the impacts different in the different habitat divisions of the aeolian community?

• Does weed density impact CV fringe-toed lizard or flat-tailed horned lizard populations? Are impacts similar for these two species?

• Does weed density impact CV milkvetch populations? Does it impact plant distribution and/or reproduction?

The County of Riverside and the City of Murrieta requested that the Regional Conservation Authority (RCA) consider a Criteria Refinement for Core 2 in Western Riverside County’s Multiple Species Habitat Conservation Plan (WRC MSHCP). The purpose of this action is to determine if Core 2 can be sustained as a reserve and if WRC MSHCP funds could be more efficiently used in other core areas. The RCA requested a review of the biological research from the Center for Conservation Biology (CCB) that could be brought into their decision-making process. The CCB convened a distinguished group of scientists to review the implications of a Core 2 Criteria Refinement to biological resources. The group evaluated three general topics at a two-day workshop in order to provide this assessment.

This report presents the first three years of research pertaining to the design, development and implementation of the monitoring program of the Coachella Valley Multiple Species Habitat Conservation Plan.

The Western Riverside County Multiple Species Habitat Conservation Plan has been presented to the public as a complete draft having been reviewed and modified as a result of comments from resource agencies, the Scientific Review Panel (SRP), local stakeholder groups, cities, and numerous other individuals at key intervals in the planning process. The goal is to develop a land-use plan that preserves open space for individual species of concern, protects existing natural communities that sustain the biodiversity of the planning region, and creates constraints for planned growth and development of the region that respect the rights of property owners. It seeks to use the “Best Available Science” as an approach to the planning process. This document is a review of the "science" in the final draft of the Western Riverside County Multiple Species Habitat Conservation Plan, by the Science Review Panel assembled by the Center for Conservation Biology at the University of California, Riverside.

The recovery plan for the California red-legged frog was reviewed. There are two main elements for our region in southern California. The first is the designation of critical habitat for recovery of this species. We suggest that the criteria for designation of critical habitat should be explicitly defined and listed. The map boundaries should then result from those criteria. This would reduce the maps to those specific areas with habitat in which recovery efforts could be made. Requiring large regions to await evaluation on an individual project basis undermines the support for the ESA and creates controversy where likely none should exist. The second element is restoration of the populations. While we support this effort, we are concerned with the use of extensive substrate disturbance in the survey for exotic pest species and the restrictive use of a single “genotype” used in recovery. Instead of seining to remove pests, we recommend careful evaluation of the literature with targeted research toward the different pests. We further suggest that having both Baja and LA populations is probably more appropriate and provides a better chance for having a survivable population.