Changes in ponderosa pine forests of the Mt. Logan Wilderness

Ponderosa pine forests in the Mt. Logan Wilderness on the Arizona Strip have become dense with young trees and highly susceptible to catastrophic wildfire due to exclusion of the natural frequent-fire regime and the effects of livestock grazing and logging associated with Euro-American land use practices. As part of a broader regional ecological restoration study, the Mt. Logan Wilderness was sampled for fire scarred trees, vegetation, and fuels between 1995 and 1997. Reconstructed fire histories show that fires recurred about every 5-6 years prior to settlement, with larger fires burning every 9-12 years. Frequent fires ceased after 1869-1879 in the Mt. Logan Wilderness, coincident with the time of Euro-American settlement, beginning a fire-free period that has lasted up to the present except for a few fires in the 1930s. Current forests are dense, ranging from approximately 700 to 3,000 trees/ha, and dominated by small trees.