Fire Mosaics in Southern California and Northern Baja California

Abstract

In spite of suppression efforts, severe wildfires burn large areas of southern California grassland, coastal sage scrub, and chaparral. Such large burns may not have been characteristic prior to the initiation of fire suppression more than 70 years ago. To compare controlled with uncontrolled areas, wildfires of southern California and adjacent northern Baja California were evaluated for the period 1972 to 1980 from Landsat imagery. Fire size and location, vegetation, year, and season were recorded. It was found that suppression has divergent effects on different plant communities depending on successional processes, growth rates, fuel accumulation, decomposition rates, and length of flammability cycles. These variables establish feedback between the course of active fires, fire history, spatial configuration of flammable vegetation, and fire size. Suppression has minimal impact in coastal sage scrub and grassland. Fire control in chaparral reduces the number of fires, not burned hectarage; fires consequently increase in size, spread rate, and intensity and become uncontrollable in severe weather conditions. The Baja California chaparral fire regime may serve as a model for prescribed burning in southern California.

Characterizing wildfire regimes in the United States

“…The term ''wildfire,'' as used in this paper, is taken to mean any burned area, irrespective of size or ignition source. Recent studies of wildfire regimes suggest frequency-area probability distributions that are power-law (8)(9)(10)(11)(12)(13) or otherwise ''heavy-tailed'' (14)(15)(16)(17)(18)(19) over many orders of wildfire area. The power-law takes the formḟ…”

“…With implications for hazard management, climate studies, and ecosystem research, there is, therefore, significant interest in appropriate analysis of historical wildfire databases. Insightful studies using wildfire database statistics exist (5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24) but are often hampered by the low spatial and͞or temporal resolution of their data sets. Here, we use a high-resolution database of wildfires for the conterminous United States (U.S.), combined with techniques drawn from recent advances in statistical physics and complexity theory, to examine U.S. wildfire statistics in a spatially and temporally explicit manner.…”

Relevance of percolation theory to power‐law behavior of dynamic processes including transport in disordered media

“…In the studies of fires in the southern California and northern Baja California montane ecotones by Minnich and coauthors [118][119][120][121], several points emerge, which are frequently mentioned in the remainder of this section. Before the era of suppression (starting in the early 20th century), fires often burned so slowly that they would take months to consume a similar amount of fuel (10,000 to 20,000…”

Forgetting fire: Traditional fire knowledge in two chestnut forest ecosystems of the Iberian Peninsula and its implications for European fire management policy

“…State fire exclusion policies seem to have, indeed, played an important role in determining the evolution of anthropogenic fire regimes not only in Spain but also throughout the world (Minnich, 1983;Kull, 2002;Seijo, 2005;Laris and Wardell, 2006;Stephens, 2008;Fernandes et al, 2014). Political scientists have hypothesized, for instance, that the same international governance rural development or environmental policies may have contrasting impacts depending on the relative "strength" or "weakness" of the implementing national state organizations (Migdal, 1988;Scott, 1999;Guha, 2000;Goldman, 2005;Seijo and Gray, 2012).…”

“…By selecting these sites we have endeavoured to ensure that the biophysical variables underlying any 7 differences in fire regimes could be held (as far as possible in a natural non-laboratory setting) constant so as to better highlight the ecological effects of different fire management recently. This is a proven methodological approach that has yielded interesting findings on changing fire regimes in other MTEs (Minnich, 1983).…”