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Table 2 FRAGSTATS spatial pattern metrics chosen to quantify attributes of fire severity, with their abbreviations and descriptions (McGarigal et al. 2002).

From: Changes in Fire Severity across Gradients of Climate, Fire Size, and Topography: A Landscape Ecological Perspective

Spatial pattern metric Description
PLAND Percent of the Landscape: proportional abundance of high-severity patches in the burned landscape; severity composition.
AREA_AM Area-weighted mean patch size: the proportional area of each high-severity patch, based on total area of all high-severity patches.
AI Aggregation Index: the number of adjacencies between high-severity cells, divided by the maximum possible number of adjacencies (0 % to 100 %). Equals 0 when there are no like adjacencies and 100 when all cells form a single, compact patch.
CLUMPY Clumpiness Index: the proportion of adjacencies of high-severity cells, scaled to reflect its deviation from that expected under a spatially random distribution, facilitating comparison of high-severity cell aggregation among landscapes (range −1 to 1).
DIVISION Division Index: based on the cumulative patch area distribution, DIVISION is the probability that two randomly chosen cells are not situated in the same high-severity patch (0 to 1). The value approaches 1 as the proportion of the landscape comprised of high severity decreases and as high-severity patches decrease in size.
CAI_AM Core Area Index (Area-weighted Mean): percentage of the high-severity patch that is greater than 100 m from an edge of lower severity, summed for all high-severity patches. The index is scaled relative to proportional abundance of high-severity patches to enable comparison among landscapes.