THE SURVIVAL OF PINUS PONDEROSA SAPLINGS TO INCREASING LEVELS OF FIRE BEHAVIOR AND IMPACTS ON POST-FIRE GROWTH

Improved predictions of tree species mortality and growth metrics following fires are important to assess fire impacts on forest succession, and ultimately forest growth and yield. In recent studies, North American conifers do not exhibit a binary response to fire where the tree either lives or dies; rather, there is a ‘toxicological dose-response’ relationship between fire behavior and the resultant mortality or recovery of the trees. Prior studies have not been conclusive due to potential pseudo-replication in the experimental design and time-limited observations. We explored whether dose-response relationships are observed in ponderosa pine (Pinus ponderosa) saplings exposed to surface fires of increasing fire behavior (as quantified by Fire Radiative Energy – FRE). We confirmed equivalent dose-response relationships to the prior studies. We further found that post-fire growth and mortality in ponderosa pine saplings corresponded to the amount of FRE applied and that, as with lodgepole pine (Pinus contorta), a low FRE dose could be applied that did not yield mortality in any of the replicates (r=10). These results suggest that land management agencies could use planned burns to protect similar fire-adapted tree species while eliminating unwanted species. Incorporation of these results into earth-system models and growth and yield models could help reduce uncertainties associated with the impacts of fire on timber growth, forest resilience, carbon dynamics, and ecosystem economics.masters, M.S., Natural Resources -- University of Idaho - College of Graduate Studies, 2019-0