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First International Gap Analysis Project

Carlos Gonzalez-Rebeles,1 Nick C. parker,1 Vincent Burke,2 Mike Jennings,3 and Gerardo Ceballos4
1 Texas Cooperative Fish and Wildlife Research Unit, Texas Tech University, Lubbock
2 USGS/BRD Environmental and Contaminants Research Center and
University of Missouri, Columbia
Gap Analysis Program, Moscow, Idaho
4 Instituto de Ecologia, UNAM, Mexico


Approximately half of the United States-Mexico border is defined by the Rio Grande (named the Rio Bravo in Mexico and here referred to as the RG/RB). The river is an important ecological component of the ecosystems it transverses, and the Texas-Mexico border region represents an area of great biological diversity. The Texas Gap Analysis Project (TX-GAP) has been making considerable strides toward completing Gap Analysis for the state, but successful completion of the project would have left a partial picture of the habitats encompassing the RG/RB. Coordinators of the USGS Lower Rio Grande Ecosystem Initiative (LRGEI) (U.S./Mexico Field Coordinating Committee 1996) proposed that Gap Analysis should be extended to include areas in Mexico adjacent to the Lower Rio Grande. The LRGEI’s mission is to assist Department of the Interior agencies with transborder inventory, monitoring, and research activities in the Lower Rio Grande basin. During 1996, NBS Director Pulliam provided funding to begin an international Gap Analysis project that extends about 180 km into Mexico. The first meeting between CONABIO (Comision Nacional para el Conocimiento y Uso de la Biodiversidad) and USGS personnel to plan the project took place in early ‘97, and CONABIO subsequently provided matching funds.

The Lower RG/RB region along the United States-Mexico border forms a basin that is about 222,000 sq. km in size (61% in the U.S. and 39% in Mexico) (Woodward and Durall 1996), and the region contains a wide variety of rare plant and animal species (Inglis 1996, Diamond et al. unpublished report). Since recent economic agreements (e.g., North American Free Trade Agreement) have the potential to promote high rates of economic and population growth on a short-term basis, there has been increased interest in this border region among state and federal agencies in both countries. The environmental impact from the anticipated development may be severe and will require careful binational planning. The viability of many species and natural communities of the RG/RB region will ultimately depend on cooperative efforts of both countries.

Cooperators in the RG/RB Gap Analysis Project include CONABIO, the USGS Environmental and Contaminants Research Center, Texas Cooperative Fish and Wildlife Research Unit, and the U.S. GAP. Additional support and participation is being sought from diverse sectors of both countries (e.g., federal and state governmental agencies, universities, research institutions and nongovernmental organizations) as the project develops. The project is the first international Gap Analysis project supported by the U.S. GAP and is one of the first joint activities undertaken since BRD and CONABIO signed (on January 19, 1995) a Memorandum of Understanding for cooperative participation in the assessment and conservation of biodiversity between both countries.

Project Description and Challenges

RG/RB-GAP will use standard GAP methods (i.e. GAP 1997). Current analyses performed for TX-GAP will be extended to Mexican lands adjacent to the Lower Rio Grande (Gonzalez-Rebeles et al. in press). A map of land cover is being produced from satellite imagery and ancillary information. Vertebrate distributions are being predicted and mapped based on knowledge of their habitat associations and the spatial representation of those preferred habitats. Land stewardship, categorized by level of management relative to conservation potential, are also being mapped. This information will be combined as digital layers and analyzed in a GIS to evaluate how the different communities, the sites of maximum species overlap (richness), or individual species distributions are represented in existing managed areas, and to identify potential "gaps" in conservation. In addition, both TX-GAP and RG/RB-GAP biological and geographic data sets will be combined for the integrated analysis and planning of land use and management of this important border region.

The study area proposed involves a region covered by fourteen Landsat satellite scene areas that span the river plus six adjacent scene areas wholly in Mexico, covering northern portions of the states of Chihuahua, Coahuila, Nuevo Leon, and Tamaulipas in Mexico (Fig. 1).

Figure 1. International GAP meeting participants (First row: D. Buckler, R. Sims, M. Jennings, G. Ceballos and R. Estrada. Second row: V. Burke, C. Gonzalez-Rebeles and N. Parker.

Figure 2. Study Area for International GAP (as covered by Landsat TM imagery).

Implementing RG/RB-GAP is challenging and exciting. For example, planning and organizing a program of cooperative participation and data-sharing among the states of both countries will not be easy. As in the U.S., different agencies and institutions within the Mexican states differ in their policies and procedures. In addition, as encountered by GAP in the U.S., the availability of biological information in Mexico and its level of detail and quality varies considerably among states. Fortunately, in recent years biodiversity data have been collected, organized, and further developed by CONABIO in coordination with major museums and universities. However, it will still be a challenge to integrate data sets among states within and between the countries into standard formats appropriate for an international gap analysis.

Linking geographic data sets will be particularly problematic. Maps from each country differ in scale and format. A regional analysis across both sides of the RG/RB will require the development of standardized versions of several map themes to complement those few maps having common characteristics. For example, the most frequently used vegetation classification schemes are fairly general (e.g., Miranda and Hernandez-X 1963, Rzedowski 1988), and vegetation studies are localized and large scale. New descriptions of vegetation formations and alliances are needed.

An advantage for RG/RB-GAP is that it was developed as a regional project from the outset. This is forcing an up-front development of strategies for standardization and merging data sets. Similar to other regional GAP projects in the U.S., this project is creating new opportunities for research and providing options for solving many of the problems facing the region. The project will also provide a better understanding about the applicability of the gap analysis approach when extended across the international boundaries.


RG/RB-GAP in combination with TX-GAP will generate valuable geographical and biological data sets and analyses to support conservation and land use planning of the Lower RG/RB ecosystems. Both projects will provide opportunities for data sharing and standardization of procedures for the assessment and monitoring of this important international region and the shared ecological and economical interests. The adaptation and refinement of techniques and procedures will help CONABIO evaluate approaches needed to apply gap analysis to the rest of Mexico. In general, the associated research and experiences derived from this project will set a benchmark for coordination of gap analysis across North America.


We thank Reynaldo Patino, Eric Holt, and Jeff Johnson for reviewing this manuscript. This is publication no. T-10-112 of the College of Agricultural Sciences and Natural Resources, Texas Tech University.

Literature Cited

Diamond, D.D., L.A. Linam, J.M. Poole, P. Melhop, and M. Trevino. 1992. Rare species and communities in the Texas-Mexico borderlands. In: Proceedings: 5th U.S./Mexico Border States Conference on Recreation, Parks, and Wildlife; Sept. 17-19, 1992, Las Cruces, New Mexico. pp 35-41.

Gap Analysis Program. 1997. A handbook for Gap Analysis. USGS/BRD Gap Analysis Program, Moscow, ID. http://www.gap.uidaho.edu/gap/.

Gonzalez-Rebeles, C., N.C. Parker, R.W. Sims, Y. Lan, and M. Cano. 1997. Spectrum software for Gap Analysis Projects in Texas and Mexico. GAP Analysis Bulletin No. 6.

Inglis, J.M. 1996. A history of vegetation on the Rio Grande Plain. Texas Parks and Wildlife Department, Bulletin No. 45. 122 pp.

Miranda, F., and E. Hernandez-X. 1963. Los tipos de vegetacion de Mexico y su clasificacion. Boletin de la Sociedad Botanica de Mexico 28. Pp. 29-179.

Rzedowski, J. 1988. Vegetacion de Mexico. Editorial Limusa, Mexico, D. F. 432 pp.

Scott, J.M., F. Davis, B. Csuti, R. Noss, B. Butterfield, S. Caicco, C. Groves, T.C. Edwards, Jr., J. Ulliman, H. Anderson, F. D’Erchia, and R.G. Wright. 1993. Gap Analysis: a geographic approach to protection of biological diversity. Wildlife Monographs 123:1-41.

U.S./Mexico Field Coordinating Committee. 1996. Lower Rio Grande Issue Team Activities for FY97. National Biological Service Document. Midwest Science Center, Columbia, MO. 65 pp.

Weakley, A.S., K.D. Patterson, S. Landaal, M. Gallyoun, and others (compilers). 1996. International classification of ecological communities: Terrestrial vegetation of the Southeastern United States. Working Draft of April 1996. The Nature Conservancy, Southeast Regional Office, Southern Conservation Science Dept., Community Ecology Group, Chapel Hill, NC. 374 pp.

Woodward, D., and R. Durall. 1996. United States-Mexico border area, as delineated by a shared water resources perspective. U. S. Department of the Interior, Field Coordinating Committee, Fact Sheet 1. 4 pp.

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