1. Introduction to Fire Ecology
The Natural Variability Concept

2. Fire Regime Characteristics
Frequency: the number of fires in a given time. This can be expressed in a number of ways:
Probability: decimal fraction of events/yr
Return Interval: the inverse of probability; years between events
Fire rotation or fire cycle: time needed to disturb an area equal in size to the study area

3. Fire Regime Characteristics
Extent: area disturbed in a given event or during a given time period
Magnitude: described by either:
Severity: biological effects of the fire (e.g. % trees killed) or
Intensity: physical force or energy released by the fire
Seasonality: season when the fire occurs

4. Fire Regime Characteristics
Variability can be critical!
The fire regime characteristics include the MEAN frequency, severity, size and season
However, the VARIABILITY in frequency, severity, size and season can also play a key role in shaping ecosystem structure and function