During a recent hike in a forested area just west of Fairbanks, Glenn Juday explains why so many of the trees are sickly.
“What we’ve seen are changes, major changes, as a result of warm-temperature anomalies,” he said.
Juday is a University of Alaska-Fairbanks forest ecology professor, and he’s studied the effect of the warming climate on Alaska’s boreal forests for some 30 years now. He says the warmer, drier conditions of the past few decades are weakening the trees, especially white spruce, making them more susceptible to insect infestation.
“Insect outbreaks are more severe, bigger – they affect more trees,” he said. “And more of the trees affected are dying.”
Insect populations previously held in check by cold winters are on the increase infesting trees weakened by damage from more frequent heavy snow and winter rains that form ice. More damage is inflicted by summer wildfires. The 2015 Alaska wildfire season was the second-biggest in recorded history.
“The fires are bigger. They’re more frequent. They’re more severe.”
Juday says researchers are reporting similar findings for boreal forests in Canada, Europe and Asia.
He and two co-authors say in a study published in 2011 that the boreal-forest species dying out in Alaska’s eastern Interior are thriving in cooler, wetter places elsewhere around the state – “west of here, higher in elevation, further north.”
He says his study provides strong evidence of how climate change is affecting the Arctic.
“We believe this is one of the first clear examples, anywhere, of a major ecosystem, or biome, of the Earth’s surface that has reached the point of what we call biome shift,” he said. “The entire system has to move to a new place.”
Juday says the vegetation that’s likely to move into Alaska’s Interior resembles that which grows around Edmonton, Alberta – nearly a thousand miles to the south.