In a recent study, University of Montana researchers explored the ways forest succession and climate variability interacted and influenced fires in Alaska’s boreal forests over the past four centuries – from 1550 to 2015.
“We reconstructed fire activity over the last 450 years using lake-sediment records,” said Tyler Hoecker, the study’s lead author.
As part of his master’s thesis work in the Systems Ecology program in the W.A. Franke College of Forestry and Conservation, Hoecker collected lake-sediment cores near the Nowitna National Wildlife Refuge in central Alaska, a fire-prone area that also has many lakes.
“Charcoal produced by fires is blown into lakes and settles to the bottom, forming a stable record of the fire history in the layers of sediment, much like fire scars on tree rings,” Hoecker said. “By carefully measuring changes in charcoal through time, we deduced changes in fire activity. We paired fire history records from seven lakes with records of tree ages and a record of climate. Then, we compared these records, looking for patterns in how the processes interacted.”
Hoecker and co-author Phil Higuera, an associate professor of fire ecology in UM’s Department of Ecosystem and Conservation Sciences, found that years of extensive fire activity usually occurred several decades after trees established, suggesting that the development of mature forest across the study landscape was necessary to support widespread burning. They also saw that there was more fire activity in years when temperatures were higher, especially over the past 100 years.
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