"Fire weather" occurs from May through November, with extreme fire conditions occurring when very dry, warm Santa Ana winds blow over dry vegetation. The area's topography exacerbates the problem, because the northeast-southwest trending canyons can pull marine air inland each day as land surfaces warm, creating up-canyon winds. At night, when temperatures cool, the breezes are pulled back down-canyon and seaward. Compared to inland portions of California, the fire hazard is generally lower in the summer at Camp Pendleton because winds there generally originate from the ocean and are moisture laden.
Both urban development and natural communities occurring within the study area have fire management issues and concerns. The threat to life and property caused by fire is clearly understood by all homeowners. What is less understood is that periodic and varied fire events are necessary for the long-term survival of native plants and habitat communities and, in turn, the area's high biodiversity. While these positions appear at odds, they share some common land management needs.
Current fire needs among natural communities vary. Some require high intensity and/or frequent fire events for successful re-generation, while other areas of sensitive populations may require protection from intense fire events. Although response to fire is variable, all of the plant communities within the area of concern have some natural adaptation to fire. Figure 40 shows the vegetation of the study area grouped by burn compatibilities, and figure 41 shows the dependence upon fire, expressed in the long-term return interval.
The practice of fire suppression, combined with a highly fragmented landscape of developed and undeveloped areas, has dramatically altered the historic fire regime of the region. The resulting natural vegetation patches are subject to elevated fuel loads and are highly susceptible to catastrophic fire events. These events pose the greatest threat to homeowners. In addition to elevating fuel loads, extended periods of fire supression may trigger a change from one habitat type to another. As a result, active fire supression can cause a long-term threat to homeowners, through risk of catastrophic fire, as well as to the natural environment, through succession to a new habitat community.
Figure 42 shows the fire risk area of 1990+. Areas most at risk are small isolated patches of vegetation and residential areas in or adjacent to vegetated areas with a high proclivity to burn. These juxtapositions are common in rural residential development. Figure 43 shows the fire risk areas of Plans Build-Out. As seen in the bar chart in figure 44, there will be a substantial increase in fire risk to people and property, and to the natural environment in fire-prone rural residential areas.
This situation will require increased fire management planning throughout the study region. Fire is an inherently stochastic process. That is, there is variability in both the recurrence of fires and intensity of the burning process. While it is possible to describe a given vegetation type's need for fire as an average fire return interval, variability in the timing of each fire is also an important aspect for this natural process. It is, therefore, necessary to mimic this variability in preemptive controlled burnings. The use of such prescribed and managed fires to assist in the protection of life and property and to maintain habitat has the potential for meeting multiple goals within a single landscape management program.
MCB Camp Pendleton has an active fire managment plan, and its scheduled burning, when coordinated with training activities, assures the maintenance of fire-dependent habitat while simultaneously protecting property. However, fire does not recognize property boundaries. Increased risk caused by development near the base will require the communities and public land agencies surrounding Camp Pendleton to coordinate fire managment planning. Addressing the role of fire in this landscape remains a key to the future of biodiversity.