Do Rules of Thumb Measure Up? Characteristics of Fire-Scarred Trees and Samples

Dendrochronologists studying fire history must be strategic in their search for fire-scarred tree samples. Because it is desirable to extend the period of analysis in a site by looking for old scars, recent scars, and trees with large numbers of scars, researchers have developed rules of thumb regarding which trees are most likely to meet these goals as well as where fire scars are most likely to be found. To test our assumptions and quantify patterns about tree and sample characteristics, we analyzed a dataset of 2800 samples and 16,036 scars. On average, logs had the oldest scars and live trees had the most recent scars, although both very old and very recent scars were found on snags and stumps. Scars tended to be located on the uphill sides of trees, particularly on steeper slopes. The number of years between pith date and first fire scar ranged from 2 to 473 years, with a median of 52 and a mean of 67. The data confirm that searching for a variety of sample types and looking on the uphill sides of trees are useful methods for efficient sampling and extending a fire history record.