Spatial domain of tree-ring fire histories. A cross-scale comparison of the largest regional fire year in the Southwest during the past 400 years: 1748. The synchrony of the 1748 fire year among fire-scarred trees at the smallest spatial scale (a forest stand) is shown in the bottom panel. Patterns of synchrony, which are a measure of the relative areal extent of fire, are then illustrated at higher levels of aggregation (larger scales, coarser grain size) up through the watershed, mountain range, and finally the regional level (uppermost panel).

Credit: Chris Baisan and Tom Swetnam. Source: Swetnam, T. W., and C. H. Baisan. 1996. Historical fire regime patterns in the southwestern United States since AD 1700. In C. D. Allen, editor, Fire effects in southwestern forests, Proceedings of the Second La Mesa Fire Symposium, March 29-31, 1994, Los Alamos, New Mexico. U.S.Department of Agriculture, U.S. Forest Service General Technical Report RM-GTR-286. 216 pp.