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Forest responses to increasing aridity and warmth in the southwestern United States

A. Park Williams, Craig D. Allen, Constance I. Millar, Thomas W. Swetnam, Joel Michaelsen, Christopher J. Still, Steven W. Leavitt
Summary - what did the authors do and why?

The authors related tree-ring growth responses to the variability in precipitation, temperature, and relative humidity in southwestern forests and woodlands and projected trends in these relationships based on future climate change scenarios. They further analyzed trends in disturbance regimes, specifically wildfire and bark beetle outbreaks.

Publication findings:

From 1984 to 2006, fire and bark beetle outbreaks have caused approximately 14-18% of the mortality in forested areas of the Southwest, and the area burned has increased substantially with a greater proportion burning at high severity since 1984. Recent elevated temperatures are thought to have led to both the increase in bark beetle outbreak and high severity fire.

Climate and Fire Linkages

How do temperature, relative humidity and vapor pressure deficit relate to annual area burned and fire size?

From 1984 to 2006, fire and bark beetle outbreaks have caused approximately 14-18% of the mortality in forested areas of the Southwest, and the area burned has increased substantially with a greater proportion burning at high severity since 1984. Recent elevated temperatures are thought to have led to both the increase in bark beetle outbreak and high severity fire.