Condition of Live Fire-Scarred Ponderosa Pine Twenty-one Years after Removing Partial Cross-Sections

Abstract

Concern over the effects of removing fire-scarred partial cross-sections may limit sampling of live ponderosa pine to reconstruct fire history. We report mortality rates for ponderosa pine trees 20 to 21 years after removing fire-scarred partial cross-sections to reconstruct fire history. In 2015, following surveys every five years since 2000, we revisited 138 trees that were alive when we sectioned them in 1994/95 and 386 similarly sized, un-sectioned neighbor trees of the same species that were also alive in 1994/95. Between 1994/95 and 2015, a significantly greater proportion of sectioned than neighbor trees died, yielding average annual mortality rates of 3.3% versus 2.2%. However, many of the trees that died were likely killed by prescribed fires in 2002 and 2003 (64 sectioned plus neighbor trees). When we excluded these trees to assess the effect of fire-scar sampling rather than the effect of modern fires, the difference in proportion of dead trees was no longer significant and yielded average annual mortality rates of 2.1% versus 1.4% for sectioned and neighbor trees. We continue to suggest that sampling live, fire-scarred ponderosa pine trees remains a generally non-lethal method of obtaining information about historical fires that can supplement the information obtained from dead fire-scarred trees. © 2017 by The Tree-Ring Society.