Fire Regime Alteration

Fire is not the enemy of many North American forests. It is their architect.

The longleaf pine once covered 90 million acres of the American South. It is one of the most biologically rich ecosystems on the continent — home to the Red-cockaded Woodpecker, the Gopher Tortoise, and hundreds of plant species found nowhere else. It evolved with fire so frequent and so reliable — every two to five years across vast stretches of the coastal plain — that it became dependent on it. Without fire, the oaks and other hardwoods that longleaf normally suppresses move in, shade out the wiregrass understory, and the entire community collapses into something that supports a fraction of the species it once did.

The ponderosa pine forests of the West tell the same story. Before European settlement, low-intensity fire moved through these open, parklike woodlands every few years, clearing the understory and preventing the accumulation of the fuel loads that drive catastrophic crown fires. A century of aggressive fire suppression — made possible and economically rational by the road network that allowed fires to be fought — has transformed these landscapes. The fuels have accumulated for decades. The forests that were once resilient to fire are now primed for the kind of catastrophic, stand-replacing fires that kill even the oldest trees and take centuries, not decades, to recover from.

Roads alter fire in two opposing directions simultaneously: they bring suppression capability, and they bring ignition. Human-caused fires — from campfires, equipment sparks, and vehicle exhaust — correlate directly with road density. In a landscape where suppression has already loaded the fuels, the ignition source that roads provide can trigger the catastrophic events that accumulated fuel makes possible.

The official definition of 7.1 Fire & Fire Management covers "management actions that either suppress or increase fire frequency and/or intensity." Its exposition is careful to note that this category "focuses on the human activities that lead to either not enough fire or too much fire in the ecosystem in question" — and that it includes "damaging natural fires in systems that have lost their natural resilience," recognizing that suppression itself creates the conditions for catastrophic fire.

In the roadless areas covered by this application: 221 species carry documented fire regime threats — including 43 critically imperiled and 65 imperiled species. More than half of all ecosystem threat narratives in the database — 124 of 231 — specifically mention fire regime alteration as a documented pressure.