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An Ecological Analysis of Conservation Priorities in the Sonoran Desert Ecoregion April 2000 Sand Tanks-Sauceda Mountains Complex: Conservation Site 32 in Arizona (Photo: R. Marshall) Sonoran Institute With Support from the Legacy Program, Agency, and Institutional Partners Preferred Citation: Marshall, R.M., S. Anderson, M. Batcher, P. Comer, S. Cornelius, R. Cox, A. Gondor, D. Gori, J. Humke, R. Paredes Aguilar, I.E. Parra, S. Schwartz. 2000. An Ecological Analysis of Conservation Priorities in the Sonoran Desert Ecoregion. Prepared by The Nature Conservancy Arizona Chapter, Sonoran Institute, and Instituto del Medio Ambiente y el Desarrollo Sustentable del Estado de Sonora with support from Department of Defense Legacy Program, Agency and Institutional partners. 146 pp. EXECUTIVE SUMMARY A bi-national team was convened in 1998 to compile and analyze biological and ecological data for the 55-million acre (22 million ha) Sonoran Desert Ecoregion, which comprises parts of Arizona, California, Sonora, and Baja, California. The objective of this project was to use a science-based approach to identify a network of Conservation Sites throughout the Ecoregion that, with proper management, would ensure the long-term persistence of the Ecoregion's biodiversity, including rare and common species, native vegetation communities, and the ecological processes needed to maintain these elements of biodiversity. The technical team convened to compile and analyze data included staff from The Nature Conservancy, Sonoran Institute, Instituto del Medio Ambiente y el Desarrollo Sustentable del estado de Sonora, and Arizona Game and Fish Department with assistance from more than 100 experts from public agencies, academic institutions, conservation organizations, Tribes, and private resource professionals. To generate awareness of the project and attract participation by natural resource entities throughout the Ecoregion we initiated an outreach program that included development of a project website and presentations at more than 20 local, regional, and national meetings, symposia, conferences, etc. We selected a representative sample of the Ecoregion's species and natural vegetation communities to serve as Conservation Targets, the basic unit of analysis for this exercise. We selected a total of 353 species from six taxonomic groups (amphibians/reptiles, birds, fish invertebrates, mammals, plants). Emphasis was placed on selecting species endemic to the Ecoregion. We also used 78 natural vegetation communities to represent a broader level of biological organization across the Ecoregion. The approach of using both fine-scale data on species and coarse-scale data on vegetation communities was presumed to be a robust way to represent the broadest array of biodiversity. We used a variety of data sets, including species' population data housed in Natural Heritage Programs, spatially-referenced data on vegetation, land use, hydrography, topography, land management, etc. To fill data gaps and obtain contemporary data we convened a two-day experts workshop at the University of Arizona where 106 experts participated from 51 agencies, universities, Tribes, private resource professionals, and conservation groups. All data were subjected to a set of Conservation Criteria that established numeric goals for each Conservation Target. Contemporary data provided by experts were used as the nuclei for identifying the network of Conservation Sites. Sites throughout the Ecoregion were evaluated for the number and types of Conservation Targets considered viable within their boundaries. We also constructed a biophysical model using spatial data for climate, vegetation, elevation, slope, and aspect to derive an independent index of the diversity of the Sonoran Desert Ecoregion. In total, 100 large landscapes and 79 small, localized areas were identified across the Ecoregion as a network of Conservation Sites where conservation opportunities should be pursued. The network includes 23,108,106 acres (9,355,508 ha) of lands in Mexico and the U.S. Landscape-scale Conservation Sites capture entire ecosystems, such as a complex of i mountain ranges and valleys, where ecological processes remain largely intact. The 79 localized Sites capture some of the Ecoregion's rarest plants and animals and were, generally, isolated from areas identified for the larger landscape Sites. When compared to the biophysical model, the identified network of landscape-scale Conservation Sites captured 89% of the Ecoregion's biophysical variation. Areas that were not adequately representedmostly in the Plains of Sonora and Arizona Uplands portions of the State of Sonorainclude some of the least well-known areas in the Ecoregion. A "GAP" management analysis of the Ecoregion revealed that, at present, less the 20% of the network of Conservation Sites is managed to promote the long-term persistence of Conservation Targets. Of the 18 Conservation Sites identified to conserve the Ecoregion's riverine, riparian, and aquatic systems, only 9% are managed to promote the long-term persistence of biodiversity. Several recommendations were identified for improving the conservation status of the network of Conservation Sites. The results of this project can serve regional and local conservation efforts by: (1) identifying the most important areas Ecoregion- wide for conservation of biological diversity; (2) providing a baseline characterization from which to evaluate the status of Conservation Targets and trends in major stressors across the Ecoregion, and; (3) providing an ecoregional context for designing and evaluating projects, drafting conservation proposals, and anticipating and framing budget needs. Given that Conservation Sites overlap lands managed by public, private, and communal entities, a variety of approaches may be needed to accomplish the overall goal of biodiversity conservation. For lands already designated for conservation purposes, implementing conservation programs that abate or minimize major stressors to Conservation Targets will enable true adaptive management. Several agencies and organizations throughout the Ecoregion are already having success with this approach. For lands in which conservation is one of multiple management goals, integrating Ecoregional data and a goals- based approach into comprehensive land management planning will help insure that the Ecoregion's biodiversity is adequately characterized, evaluated, accounted for, and conserved through development of appropriate management programs. For lands in which the goal does not include conservation, opportunities should be identified to increase attention to conservation of biodiversity by developing collaborative programs among public and private entities (e.g., U.S. Fish and Wildlife Service's Partners for Wildlife Program, UMA or environmental management area designations in Sonora, conservation easements, etc.). ii ACKNOWLEDGMENTS This ecological characterization of the Sonoran Desert Ecoregion would not have been possible without the support of numerous people working on biodiversity conservation issues in Northwest Mexico and the Southwestern U.S., including staff from federal, state, and local agencies, Native American Tribes, academic institutions, conservation organizations, and private corporations (see list below). We wish to express special appreciation to Peter Boice, Director of Conservation in the Office of the Assistant Deputy Under Secretary of Defense, Thomas McCall, Jr., Deputy Assistant Secretary of the Air Force, Ms. Sheri Goodman, Deputy Undersecretary for Defense (Environmental Security) and Principal member of DOD-DOI-USDA Integrated Military Land Use Coordinating Committee, James Ohmans, Chief of Conservation Programs Headquarters U.S. Marine Corps, Colonel Fred Pease, Chief of Range and Airspace Division Air Force, J. Douglas Ripley, Natural Resource Manager for the Air Force, and Colonel Thomas Lillie, Military Liaison to the Department of Interior for their support of this project. Funding and technical support was provided by the Department of Defense Legacy Program and from agency and institutional partners. Input from those with taxonomic and natural resource management expertise within the Sonoran Desert Ecoregion was critical for providing contemporary information on the distribution, abundance, and viability of species and natural communities, and on current threats and management opportunities. The following experts graciously assisted in this process by participating in the May 1998 two-day Experts Workshop held in Tucson, Arizona, and/or by providing additional information after the May workshop: John Anderson, Roy C. Averill–Murray, Rich Bailowitz, Robert X. Barry, Bob Basney, R. Mitchel Beauchamp, Gary Bell, Robert Berry, Steve Boyd, Mark Briggs, Angie Brooks, Pat Brown, Stephen Buchmann, Anthony Burgess, William Calder, Faustino Camarena, Jose Campoy, Alejandro Castellanos, Carlos Castillo, Mario Cirett, Pat Comer, Troy Corman, Steve Cornelius, Jim Cornett, Robin Cox, Richard Crowe, Kevin Dahl, Virginia Dalton, Jose Delgadillo, Russell Duncan, Roberto Enriquez, Angie Evenden, Exequiel Ezcurra, Mima Falk, Richard Felger, Jefford Francisco, Alejandro Gerardo, Rich Glinski, Matt Goode, Larry Gorenflo, Dave Gori, Annita Harlan, Andy Holdsworth, Ken Kingsley, Michael L'Annunziata, Hector Licon, Patricia Lock-Dawson, Rigoberto López, Eduardo Lopez Saavedra, Augustin Flores Macias, Miguel Macias, Barbara Massey, Gene Maughn, Roberto de la Maza, Mitch McClaran, Steven P. McLaughlin, Eric