Environmental News Network - Extreme Heat, Dry Summers Main Cause of Tree Death in Colorado’s Subalpine Forests

Details: By University of Colorado at Boulder; 26.Jul

Even in the absence of bark beetle outbreaks and wildfire, trees in Colorado subalpine forests are dying at increasing rates from warmer and drier summer conditions, found recent CU Boulder research.

Cheryl Porter

Even in the absence of bark beetle outbreaks and wildfire, trees in Colorado subalpine forests are dying at increasing rates from warmer and drier summer conditions, found recent CU Boulder research.

The study, published in February in the Journal of Ecology, also found that this trend is increasing. In fact, tree mortality in subalpine Colorado forests not affected by fire or bark beetle outbreaks in the last decade has more than tripled since the 1980s.

“We have bark beetle outbreaks and wildfires that cause very obvious mortality of trees in Colorado. But we’re showing that even in the areas that people go hiking in and where the forest looks healthy, mortality is increasing due to heat and dry conditions alone,” said Robert Andrus, lead author of the study and postdoctoral researcher at Washington State University. “It’s an early warning sign of climate change.”

Dead trees in subalpine Colorado forest on Niwot Ridge, west of Boulder. (Photo Credit: Robert Andrus)

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Extreme Heat, Dry Summers Main Cause of Tree Death in Colorado’s Subalpine Forests