A new study, using a first-of-its-kind approach to analyze satellite imagery from boreal forests over the last three decades, found that fire may be changing the face of the region in a way researchers did not previously anticipate.
Historically, fires in North American boreal forests have led to coniferous trees being supplanted by deciduous trees, which are faster growing, take up more carbon and reflect more light, leading to cooling of the climate and decreased likelihood of fire.
The study, led by Northern Arizona University and published today in Nature Climate Change, found that, surprisingly, while forests do become more deciduous, they don’t stay that way; a few decades later, the same forests gradually start to shift back toward coniferous trees. Researchers also found that the abrupt loss of coniferous forests caused by wildfire was offset by the gradual increase in coniferous forests in areas that had not recently burned, so there was no overall shift toward deciduous cover.
“This was somewhat surprising because several recent studies suggested there were shifts toward deciduous forests at local to regional scales,” said Logan Berner, assistant research professor in SICCS and study co-author. “While our study indicates there have not been whole-sale shifts in forest composition during recent decades, we anticipate that continued climate warming and increased wildfire activity could lead to pronounced changes in forest composition over the coming decades.”
The team conducted the research as part of NASA’s Arctic Boreal Vulnerability Experiment (ABoVE), of which Goetz is the Science Team Lead. As part of their project within ABoVE, they used high-resolution satellite imagery of the boreal forests across Alaska and Canada captured by the Landsat series of satellites to quantify changes in forest composition, both in areas that have burned and those that haven’t. They also quantified the effects of changing forests using satellite measurements of surface reflectivity and calculated the feedback effects on climate.
