Ecological Implications of Fire Suppression
By Mark Hudson
Photo courtesy of Getty Images/Yelantsevv
The ecological consequences of containing fire vary enormously from place to place. Different forest types and tree species have evolved in different fire regimes, and the removal of fire will accordingly have different results. I do not intend to review here the literature on fire ecology in the West, but the interested reader has no shortage of excellent resources to consult. The relevant issue for this book is that ecologists across the board agree that the drive to remove fire from the forests is akin ecologically to removing sunlight or rain. Burning is a key ecological process that both shapes and is shaped by the structure and character of the forest. Fire’s frequency, distribution, and intensity will affect the distribution and health of forest types and tree species, and some tree species are highly dependent on fire – either at frequent or infrequent return intervals – for their reproduction. Ponderosa pine (Pinus ponderosa), for example, relies on frequent, low-intensity burns to wipe out less fire-resistant competitors. Coastal Douglas fir (Pseudotsuga menziesii var. menziisii), on the other hand, counts on high-intensity, infrequent fires to help it out-compete more shade-tolerant species.
Vegetative structure and distribution have major effects on the size, distribution, and viability of wildlife populations as well. Contrary to the message conveyed by the teary-eyed critters depicted on Smokey Bear posters and the terrifying imagery of Walt Disney’s Bambi, forest fires kill and harm relatively few animals, since most can either flee or find shelter with considerable ease. Once the fires have passed, new habitat is created in dead and downed trees, and new growth provides food for small mammals, deer, and elk – which, in turn, provide prey for various predators. In short, the plant and animal communities we see today have evolved in tandem with the shifting pattern of fire and forests that emerged after the last Ice Age, about 11,000 years ago. The removal of that process has predictably had major but differentiated consequences.
Cover courtesy of University Press of Colorado
To gain a firmer grasp of what ninety years of suppression has meant for the flammability and health of western forests, fire scientists have attempted to classify the extent of departure from historical fire regimes (pre–European settlement) using the concept of the Fire Regime Condition Class (FRCC). This is a three-tier classification system (FRCC 1 through 3) in which FRCC 1 represents the least difference between current and historical conditions and FRCC 3 rep- resents the most difference. On lands labeled FRCC 1 – particularly those with historically long fire-return intervals (such as on the western side of the Cascade Mountains in Oregon and Washington) – the history of suppression has made little difference. On FRCC 3 lands – often those with historical fire regimes that have a frequent fire-return interval (0–35 years) – the difference is significant (as, for example, is the case in central and southern Oregon) and may also have been altered by logging, grazing, or the introduction of exotic species. FRCC 3 lands are defined as those at high risk of losing key ecosystem components. The USFS has classified 26 percent of National Forest lands as FRCC 3 and 41 per- cent as FRCC 2. In short, the Forest Service has declared that 132 million acres (of a total of 197 million acres) are at moderate or high risk from wildland fire.
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