Russia’s boreal forest is the largest continuous expanse of forest in the world. It is located in the northern reaches of the country, includes much of Siberia, and is approximately the size of the contiguous United States.
And according to new research, the Great Russian forest is undergoing a continually accelerating large-scale shift in vegetation types as a direct result of the warming climate.
In turn, the shift in the vegetation is creating its own warming climate, amplifying the overall change in the region’s weather.
“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 University of Virginia’s Graduate School of Arts & Sciences. “This will promote additional warming and vegetation change, particularly in areas with low species diversity.”
The evergreen conifers are more tolerable of warmer climates, and as warmer temperatures seep northward, so too do the evergreens, which push out the larch trees.
This might not sound like a problem on the face of things – it’s simply a shift in what sort of tree exists – but looking deeper into the change shows potentially catastrophic changes are afoot in the region.
Larch trees drop their needles in the fall, which allows the snow to fall on top of the needles and then reflect winter sunlight and heat back into space.
Conversely, evergreen conifers such as spruce and fir don’t drop their needles at all. Instead, they absorb sunlight which causes ground-level heat retention, which in turn creates wonderful conditions for the increase of evergreen conifers, pushing and diminishing the larch farther-northward and creating less ground to reflect heat and sunlight back into space.
This “positive feedback” cycle of warming is a common problem amongst many of the northern reaches of our planet.
“What we’re seeing is a system kicking into overdrive,” said co-author Hank Shugart, a University of Virginia professor of environmental sciences. “Warming creates more warming.”
“Such changes in that vast region have the potential to affect areas outside of the region,” Shuman noted.
The Russian boreal forest sits over a massive storehouse of carbon dioxide which is locked up in the permafrost. As the trees change from deciduous to evergreen, the warming of the ground surface could cause decomposition of the soil which in turn would release massive amounts of carbon dioxide back into the atmosphere.
How much?
Data suggest that it could be as much as 15 percent of the carbon dioxide already in the atmosphere.
“This is not the scenario one would want to see,” Shugart said. “It potentially would increase warming on a global scale.”
Previous research has also shown that the Arctic is due for similar changes to its ecosystems.
Source: University of Virginia
