The study region is an 80 kilometer x 134 kilometer rectangle that encompasses the five major river drainage basins directly influencing Camp Pendleton: San Juan, San Mateo, San Onofre, Santa Margarita, and San Luis Rey. The research strategy is based on the hypothesis that the major stressors causing biodiversity change are related to urbanization. As population increases and development spreads, habitat is lost due to grading, paving, ornamental landscaping, and other human activities. There are also indirect, secondary, and cumulative effects on vegetation by development through hydrologic and fire influences. These affect habitat and, ultimately, biodiversity.
A computer-based Geographic Information System was developed to describe the region. Analytical models use the digital data to evaluate the complex dynamic processes at work in the very large study area and the possible impacts on biodiversity resulting from changes in land use.
Future change is studied at four scales: several restoration projects, a subdivision, a third order watershed, and the region as a whole. Regional change is simulated via six alternative projections of development to the year 2010 and to subsequent "build-out." The first scenario is based upon the current local and regional plans as summarized by the Southern California Association of Governments, the San Diego Association of Govenments, and those of Camp Pendleton. Five alternative scenarios provide a method to explore and compare the impacts of different land use and development policies relating to biodiversity. Alternative #1 illustrates what may be considered the dominant spread pattern of low-density growth. Alternative #2 also follows the spread pattern, but introduces a conservation strategy in the year 2010. Alternative #3 proposes private conservation of biodiversity by encouraging large-lot ownership adjacent to and encompassing important habitat areas. Alternative #4, focuses on multi-centers of development and new communities. Lastly, Alternative #5 concentrates growth in a single new city. All alternatives accommodate the population forecast for the region.
A set of process models is used to assess each alternative. The soils models evaluate the agricultural productivity of the area's soils. The hydrology models predict the 25-year storm hydrographs for each of the rivers and their subwatersheds, flooding heights and water discharge, and resultant soil moisture. The fire models assess both the need for fire in maintaining vegetation habitat, and the risks of fire and fire suppression. The visual model assesses scenic preferences for the regionŐs landscape. Biodiversity is assessed in three ways: a landscape ecological pattern model; ten selected single species potential habitat models; and a species richness model.
The evaluations of the alternatives may be used by stakeholders, including MCB Camp Pendleton, to assess the desirability of the policies which generated them or to devise and compare additional development scenarios and conservation strategies.
While the research team is not making specific recommendations as part of this program, we do hope to increase understanding of the risks and benefits of a range of alternatives for the Camp Pendleton region and to provide tools and techniques which may be helpful in managing the processes of urbanization and landscape change for its several political units and its many stakeholders.