This dataset is essential to identifying high priority areas most in need of burn treatment to optimize the use of limited funding.

Fire return interval is the average period between fires in a given area. In Sequoia and Kings Canyon National Parks, fire return interval is estimated using vegetation type. The estimation is based primarily on reconstructed fire history chronologies derived from tree-ring samples obtained from fire-scarred trees in the vicinity of the parks, or from the literature if the information for a vegetation type did not exist from within or near the park. To provide a conservative estimate, the maximum average return interval for each vegetation class is used.

Fire return interval departure quantifies the difference between the expected and actual fire frequency in each vegetation type. It is calculated using the equation:

(Time Since Last Fire - Fire Return Interval) / Fire Return Interval

The time since last fire is derived from historic fire records or based on the last widespread fire date recorded by fire history reconstructions. The longer a time interval exceeds the historic return interval without a fire, the higher the priority rating for returning fire to this area. The priority ratings are classified according to how many return intervals have been missed. (The departure index ranges from -1 to 20 with 20 being the most extreme deviation from historic fire regimes.)

1: Extreme (5 or more intervals missed) 2: High (2-5 intervals missed) 3: Moderate (0-2 intervals missed) 4: Low/None (Less than 0 intervals missed) 99: Rock/Water (Nonburnable)