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 University of Colorado Boulder research.
“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 in the School of the Environment at Washington State University. “It’s an early warning sign of climate change.”
“It was really surprising to see how strong the relationship is between climate and tree mortality, to see that there was a very obvious effect of recent warmer and drier conditions on our subalpine forests,” said Andrus, who conducted this research while completing his graduate degree in physical geography at CU Boulder. “The rate of increasing mortality is alarming.”