Ponderosa pine mortality in the Bob Marshall Wilderness after successive fires over 14 years | Ponderosa pine mortality in the Bob Marshall Wilderness after successive fires over fourteen years
2020
Flanary, Sarah J. | Keane, Robert E.
Fire exclusion since the 1930s across western U.S. landscapes has greatly altered fire regimes and fuel conditions. After a lightning-caused fire swept through the center of the Bob Marshall Wilderness Area in 2003, researchers initiated a comprehensive study along the South Fork of the Flathead River. This study assessed the post-fire survival of over 600 iconic, relict ponderosa pine trees. These trees are of great interest as they are ancient (>400 years old), and some have Native American bark-peeling scars and fire scars. This area had not seen fire since 1910, if not earlier, despite having frequent fire (20-30 year fire return interval) prior to European settlement. Some of the trees sampled in 2003 experienced another fire in 2011 (Hammer Creek Fire). In 2017, these trees were remeasured for post-fire mortality by size class for the fifth time since the 2003 Little Salmon Complex fires. We found that mortality rates were quite low (<8%) for the larger trees (>20 inches diameter) despite the heavy pre-suppression fuel buildup and recent insect outbreaks. Ponderosa pine mortality rates remained somewhat low (<24%) throughout the sample period (2003-2017) with the larger trees having the least mortality (<18%) and the smaller trees having approximately 24% mortality. These surviving large relict ponderosa pine trees continue to thrive in the sampled areas despite a second Hammer Creek wildfire in 2011 that burned in the high fuel loading conditions created by the 2003 Little Salmon Fire
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