Reexamining Fire Suppression Impacts on Brushland Fire Regimes

Abstract

California shrubland wildfires are increasingly destructive, and it is widely held that the problem has been intensified by fire suppression, leading to larger, more intense wildfires. However, analysis of the California Statewide Fire History Database shows that, since 1910, fire frequency and area burned have not declined, and fire size has not increased. Fire rotation intervals have declined, and fire season has not changed, implying that fire intensity has not increased. Fire frequency and population density were correlated, and it is suggested that fire suppression plays a critical role in offsetting potential impacts of increased ignitions. Large fires were not dependent on old age classes of fuels, and it is thus unlikely that age class manipulation of fuels can prevent large fires. Expansion of the urban-wildland interface is a key factor in wildland fire destruction.

Power Laws, Highly Optimized Tolerance, and Generalized Source Coding

“…Alternatively, landscapes which naturally break forests into regions of fractal dimension lower than 2 would have steeper power laws. For example, brush fires in California occur in unusually rugged terrain, and data [11] plotted similar to Fig. 1 are an equally good match to the PLR prediction with b 1.…”

“…Decreasing the effective dimension in both the WWW and FF PLR formulations leads to steeper power laws, since for small b microscopic resources are more efficient in suppressing large events. Comparisons of the brush fire data [11] and the forest fire data [2], as well as the 1995 web statistics [1] compared to more recent results [9] both lead to an effectively reduced dimensionality, and steeper power laws. All these examples support the statistical trends predicted by HOT, and deviate from those associated with criticality, independent of the specific values of the exponents.…”

Fire‐stimulated reproduction in the resprouting, non‐serotinous conifer Podocarpus drouynianus (Podocarpaceae): the impact of a changing fire regime

“…While much attention has been paid to the vulnerability of fire-killed species to shortened fire intervals (Enright et al 1996;Keeley et al 1999;Westerling et al 2011), resprouting species have been largely treated as uniformly highly resistant to altered fire regimes. However, some proportion of any resprouter population will be killed by fire, with further individuals dying during the subsequent inter-fire period, so that population maintenance still ultimately depends on adequate seedling recruitment.…”

The recent fire history of the Table Mountain National Park and implications for fire management

“…The relaxation of rigid influx controls under the apartheid government in the 1980s, which accelerated economic growth over the past decade, and increasing immigration into urban areas have all contributed to the rapid growth of the human population in the area. Increases in human population have been shown to be correlated with increases in fire frequency in Californian chaparral ecosystems (Keeley et al 1999, Keeley & Fotheringham 2001, and it appears that similar trends may now be occurring in the Table Mountain National Park.…”