Do partial cross sections from live trees for fire history analysis result in higher mortality 2 years after sampling?

Abstract

Although partial cross sections from live trees have been utilized in the development of fire history studies, few efforts have been made to examine the effects of this method on the individual trees that were sampled. We examined 115 red pine ( Pinus resinosa Ait.), eastern white pine ( Pinus strobus L.), and jack pine ( Pinus banksiana Lamb.) trees from which partial cross sections had been removed 2 years earlier, and 209 similarly sized neighboring red pine and eastern white pine trees. Two years following the removal of partial cross sections, 22 sampled trees (19%) had died. When compared with neighboring trees, removing a partial cross section did not appear to increase the mortality rate for a given tree ( t-test; P = 0.150). However, when we compared the characteristics of the trees with partial cross sections removed, we did observe some trends; i.e., those trees that died were primarily killed by wind-induced breakage at the level of the partial cross section. Almost all stems where partial cross sections were collected from a catface edge or had >30% of the total area removed were more susceptible to stem breakage and experienced an increased likelihood of mortality. While these results suggest that the collection of partial cross sections from live trees may be an effective method for fire-history sampling, the negative impacts of the sampling on individual trees may be reduced by ensuring that samples are collected from the center, rather than the catface edge, and <25% of the total stem area is removed.