Russian boreal forests undergoing vegetation change

Fariss Samarrai in University of Virginia Today: 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.

…"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."

…The researchers used a climate model to assess what would happen if evergreens continued to expand their range farther north and larch species declined. The "positive feedback" cycle of warming promoting warming showed an increase of absorbed surface warming. The model takes into account detailed information about tree growth rates, and the results agree with actual field studies documenting changes in cone production and movement of evergreen treelines northward.

…The Russian boreal forest sits over a tremendous repository of carbon-rich soil frozen in the permafrost. As the forest changes in species distribution from larch to evergreens, warming of the ground surface would cause decomposition of the soil, releasing huge quantities of carbon dioxide into the atmosphere – possibly as much as 15 percent of the carbon dioxide currently in the atmosphere. "This is not the scenario one would want to see," Shugart said. "It potentially would increase warming on a global scale."…

Jack London Lake near Kolyma in Siberia, shot by Bartoshd, Bartosh Dmytro, Ukraine, Kiev, http://fotostudio.com.ua, Wikimedia Commons, under the Creative Commons Attribution 3.0 Unported license