Comparison of Leaf Moisture Content and Ignition Characteristics among Native Species and Exotic Conifers in Northwestern Patagonia, Argentina

Abstract

The forest–steppe ecotone in Argentine Patagonia has been planted with non-native Pinus ponderosa, Pseudotsuga menziesii, Pinus radiata, and P. contorta. As in many other planted areas of the Southern Hemisphere, there is great concern about increasing landscape flammability. We determined, under lab conditions, live fuel moisture content (LFMC) and leaf ignition of these conifers, a naturalized poplar, and 13 native species. The mean LFMC was inversely related to leaf ignition of these species. The conifer LFMC was lower than that of most natives, making the conifers the most ignitable species. Pinus ponderosa and Pseudotsuga menziesii showed the spring dip phenomenon (i.e., low LFMC in early spring). Leaf ignition and LFMC may help elucidate some flammability components at species levels. At landscape scales, however, they have to be evaluated along with other landscape traits such as structure and stand composition. Understanding this landscape context will require full-scale experimental fires. Nevertheless, our results provide useful information for fire danger assessment, and also for setting policies aimed at planning and applying appropriate silvicultural techniques for fire prevention and control, and hence reducing fire danger at stand or landscape levels.