Both models, below, were used to quantify fire effects on the 1994 Glacier Park burns. As a continuum, NBR difference was the best predictor of burn severity. However, it can be partitioned into severity levels or classes, on statistical grounds, if desired. Number and range of classes is flexible depending on the application. Here we identify five levels, including unburned, with statistical characteristics shown, below.
Selected imagery compares indices and seasons as continuous measures of burn severity.
At bottom right, differenced NBR is partitioned into the 5 severity levels, plus meadow burns. An additional advantage of this method is demonstrated by the ease and reliability of delineating burn perimeters. As needed, severity classes can be mapped to simplify interpretations. Cross-burn comparisons with standardized measures is a major benefit of this method. Here, Adair Fires burned more area, but generally less severely than the Starvation Fire.