Recovery Plan for Vernal Pools of Southern California VERNAL POOLS of SOUTHERN CALIFORNIA
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Recovery Plan for Vernal Pools of Southern California VERNAL POOLS OF SOUTHERN CALIFORNIA RECOVERY PLAN September 1998 U.S. Department ofthe Interior Fish and Wildlife Service Region One, Portland, Oregon VERNAL POOLS OF SOUTHERN CALIFORNIA RECOVERY PLAN Prepared by: Ellen Bauder, PhD. Department ofBiology, San Diego State University San Diego, California D. Ann Kreager Biologist U.S. Fish and Wildlife Service Carlsbad Field Office Scott C. McMillan Department of Biology San Diego State University San Diego, California Published by: Region 1 U.S. Fishand Wildlife Service Portland, Oregon Approved: Date: I DISCLAIMER PAGE Recovery plans delineate actions which are believed to be required to recover or protect listed species. Plans are published by the U.S. Fish and Wildlife Service, sometimes prepared with the assistance of recovery teams, contractors, State agencies, and others. Objectives will be attained and any necessary funds made available, subject to budgetary and other constraints affecting the parties involved, as well as the need to address otherpriorities. Recovery plans do not necessarily represent the views nor the official positions or approvals of any individuals or agencies (involved in the plan formulation), other than the U.S. Fish and Wildlife Service. They represent the official position ofthe U.S. Fish and Wildlife Service only after they have been signed by the Regional Director as approved. Approved recovery plans are subject to modification as directed by new findings, changes in species status, and the completion of recovery tasks. Literature citations should read as follows: U.S. Fish and Wildlife Service. 1998. Vernal Pools of Southern California Recovery Plan. U.S. Fish and Wildlife Service, Portland, Oregon. 113+ pp. Additional Copies may be purchased from: Fish and Wildlife Reference Service 5430 Grosvenor Lane. Suite 110 Bethesda, Maryland 20814 301/492-3421 or 1-800-582-3421 The fee for the Plan varies depending on the number of pages of the Plan. i ACKNOWLEDGMENTS The U. S. Fish and Wildlife Service extends its appreciation to the numerous individuals who, over the course ofyears, contributed to the conservation of vernal pooi species and the development of this plan: Meryl Balko, Tony Bomkamp, Dave Bramlett, Coralie Hull Cobb, George Cox, Jim Dice, Tom Ebert, Wayne Ferren, Bonnie Hendricks, Larry Hendrickson, Robert Holland, Ann Howald, Stacey Huddleson, Paula Jacks, Edie Jacobsen, Dawn Lawson, Emilie Luciani, Kim Marsden, Brenda L. McMillan, Tom Oberbauer, Cameron Patterson, Lauren Wei, John Rieger, Carla Scheidlinger, Marie Simovich, Fred Sproul, Michael Stroud, and Paul Zedler. Further acknowledgments are extended to the various agencies and jurisdictions who have contributed to the preservation and management ofthis special resource: United States Army Corps of Engineers, Marine Corps Base Camp Pendleton, Naval Facilities Engineering Command, Southwest Division, San Diego Association ofGovernments, California Department of Fish and Game, California Department ofTransportation, District 11, Counties of San Diego, Orange, and Riverside, and the Metropolitan Water District. Special thanks are extended to Fred M. Roberts, Jr., Julie Vanderwier, Susan Wynn for assistance on the distributional and site-specific information utilized in the development ofthe maps and tables, and the following individuals who provided valuable peer review: Denton Belk, Ellen Cypher, Eric Stein, and Marie Simovich. ii EXECUTIVE SUMMARY OF THE RECOVERY PLAN FOR THE VERNAL POOLS OF SOUTHERN CALIFORNIA Current SDecies Status: This plan addresses six vernal pool species that are listed as endangered and one that is proposed for threatened status: Eryngium aristulatum var. parishii (San Diego button-celery), Orcuttia calfornica (California Orcutt grass), Pogogyne abramsii (San Diego mesa mint), Pogogyne nudiuscula (Otay mesa mint), Riverside fairy shrimp (Streptocephalus woottoni), San Diego fairy shrimp (Branchinecta sandiegonensis), and Navarretiafossalis (spreading navarretia). Pogogyne abramsii was listed as endangered on September 28, 1978. Pogogyne nudiuscula, Orcuttia ca1~fornica, Eryngium aristulatum var. parishii, and the Riverside fairy shrimp were listed as endangered on August 3, 1993. The San Diego fairy shrimp was listed as endangered on February 3, 1997. Navarretia fossalis was proposed for listing as threatened on December 15, 1994. Historically, San Diego, vernal pool habitatprobably covered no more than 6 percent ofthe county, approximately 520 square kilometers (200 square miles). Currently levels estimate a loss of vernal pool habitat in the San Diego County around 95 to 97 percent because ofintensive cultivation and urbanization (Bauder and McMillan 1998). Lack ofhistorical dataprecludes the same depth of analysis for Los Angeles County, Riverside County, Orange County, or San Bernardino Counties, but losses are considered nearly total (USFWS 1993). The current distribution ofpools in northern Baja California, Mexico, probably comes much closer to the historic condition (Bauder and McMillan 1998). Habitat Requirements and Limiting Factors: Following winter rainstorms, vernal pools form in depressions above an impervious soil layer or layers. Water evaporates from these pools during the spring and early summer. Vegetation communities associated with adjacent upland habitats that surround the vernal pools in southern California are valley needlegrass grassland, annual grasslands, coastal sage scrub, maritime succulent scrub, and chaparral. iii Prior to 1945, the primary threats to southern California vernal poois were grazing. water impoundments, and conversion to agriculture. In recent years, urbanization and construction of infrastructure have resulted in losses of habitat estimated to be as high as 97 percent. Urbanization can directly impact pools through elimination of the habitat by soil alteration, vegetation alteration, alterations in hydrological regimes, and water quality. Where pools remain the indirect threats from dumping, trampling, vehicular activity, runoff, and intrusion ofnonnative species can cause profound changes in the pool flora. Recovery Objective: The goal of this plan is conserve and enhance southern California vernal pool ecosystems, with specific emphasis on stabilizing and protecting existing populations of Eryngium aristulatum var. parishii, Pogogyne abramsii, Pogogyne nudiuscula, Orcuttia californica, and San Diego and Riverside fairy shrimp so that these species may be reclassified from endangered to threatened status. The goal of this plan for Navarretiafossalis, currently proposed for listing as threatened, is to ensure the long-term conservation of this species. Recovery Criteria Reclassification to threatened status may be considered for Eryngium aristulatum var. parishii, Pogogyne abramsii, Pogogyne nudiuscula, Orcuttia ca/Wornica; San Diego and Riverside fairy shrimp; and the long-term conservation of Navarretia fossalis, a species proposed as threatened, will be assured when the following criteria are met: 1. The following conditions must be met to maintain the current status of Navarretiafossalis, Eryngium aristulatum var. parishii, Pogogyne abramsii, Pogogyne nudiuscula, Orcuttia caiWornica, and San Diego and Riverside fairy shrimp in order to maintain genetic diversity and population stability of the listed species and other sensitive species: Existing vernal pools currently occupied by Orcuttia cal~fornica, Pogogyne nudiuscula, and Riverside fairy shrimp and their associated iv : watersheds should be secured from further loss and degradation in a configuration that maintains habitat function and species viability; Existing vernal pools and their associated watersheds within the Transverse and Los Angeles Basin-Orange Management Areas should be secured from further loss and degradation in a configuration that maintains habitat function and species viability; Existing vernal pools and their associated watersheds within the San Marcos vernal pool complexes that contain Navarretiafossalis, Eryngium aristulatum var. parishii, or any other vernal pool species, should be secured from further loss and degradation. Habitat functions and species viability for any ofthe remaining vernal pools and their associated watersheds within the San Marcos complexes must be ensured; Existing vernal pools and their associated watersheds within the Ramona complexes that contain Eryngium aristulatum var.parishii, Navarretia fossalis, San Diego fairy shrimp, or any other vernal pool species, should be secured from further loss and degradation in a configuration that maintains habitat functions and species viability; Existing vernal pools and their associated watersheds within the Hemet complexes that contain Navarretiafossalis, and Orcuttia californica, or any other vernal pool species, should be secured from further loss and degradation in a configuration that maintains habitat functions and species viability, Existing vernal pools and their associated watersheds located on Stockpen soils (Otay Mesa) should be secured from further loss and degradation in a configuration that maintains habitat functions and species viability, to provide for the recovery of species restricted to this soil type (i.e., Pogogyne nudiuscula); and Remaining vernal pools and their associated watersheds contained within the complexes identified in Table 4 must be secured in a configuration that v maintains habitat function and species viability (as determined by prescribed research tasks). 2. The existing