Russia's boreal forest the largest continuous expanse of forest in the world, found in the country's cold northern regions is undergoing an accelerating large-scale shift in vegetation types as a result of globally and regionally warming climate. That in turn is creating an even warmer climate in the region, according to a new study published in the journal Global Change Biology and highlighted in the April issue of Nature Climate Change.
The Great Russian forest, which includes much of Siberia, is the size of the contiguous United States. It has experienced significant documented warming over the last several decades. As a result, tree species that are more tolerant of warmer weather are advancing northward at an increasing rate as species that are less tolerant to a warmer climate are declining in number.
"We've identified that the boreal forest, particularly in Siberia, is converting from predominantly needle-shedding larch trees to evergreen conifers in response to warming climate," said the study's lead author, Jacquelyn Shuman, a post-doctoral research associate in environmental sciences in U.Va.'s Graduate School of Arts & Sciences. "This will promote additional warming and vegetation change, particularly in areas with low species diversity."
Larch trees drop their needles in the fall, allowing the vast snow-covered ground surface of winter to reflect sunlight and heat back into space. This helps keep the climate in the region very cold. But evergreen conifers, such as spruce and fur, retain their needles year round. These trees absorb sunlight, which causes ground-level heat retention. This creates ideal conditions for the proliferation of evergreens, to the detriment of the leaf-dropping larches. The result is a northward progression of evergreens and a farther-northward retreat by the larch forests.
"What we're seeing is a system kicking into overdrive," said co-author Hank Shugart, a U.Va. professor
|Contact: Fariss Samarrai|
University of Virginia