Seasonal Position of Fire Scars

NPS graphic

This image illustrates the potential position of fire scars within an annual growth ring. It shows specific areas of an annual ring used to designate intra-annual fire-scar positions. Through detailed examination of where a scar was formed within a ring the approximate season of past fire occurrence can often be determined. Understanding the tree-ring growth phenology in a particular area further enhances the interpretation of this information.

In the Sierra Nevada scars formed in the earlywood (EE to LE) indicate fire occurrence during early-to-mid summer (uncommon in the southern Sierra Nevada). Scars formed in the latewood (L) indicate fire occurrence during late summer while dormant season scars (D) indicate fires late in a year (latewood and dormant season scars are the most common in this region).

Image source: Figure 2 from Caprio, A.C., Swetnam, T.W. 1995, Historic Fire Regimes Along an Elevational Gradient on the West Slope of the Sierra Nevada, California. pp 173-179 In: Proceedings: Symposium on Fire in Wilderness and Park Management, September 1995. USDA Forest Service, Intermountain Research Station, General Technical Report INT-GTR-320.