U.S. Fish Wildlife Service
America's National Wildlife Refuge System
MANAGING INVASIVE PLANTS: Concepts, Principles, and Practices
Fire Regime Condition Classes
Condition Class 1: Fire regimes are within their historical range, with a low risk of losing key ecosystem components during a fire.
Condition Class 2: Fire regimes have been moderately altered from their historical range, with a moderate risk of losing key ecosystem components during a fire. Fire frequencies are one or more fire return intervals away from historical frequencies.
Condition Class 3: Fire regimes have been significantly altered from their historical range, which a high risk of losing key ecosystem components. Fire frequencies are multiple return intervals away from historical frequencies. Vegetation attributes have been significantly altered from their historical range.
Map credit: USDA Fire Sciences Laboratory, Rocky Mountain Research Station.