Tiny organisms are making big moves in Alaska’s boreal and Arctic ecosystems, encouraged by climate change.
Underground fungi and bacteria are becoming more active as permafrost thaws in northern regions, breaking down dead plants and other organic matter that was previously frozen in the soil. Scientists call this new activity a “microbial awakening.”
A new study led by U.S. Forest Service research biologist Phil Manlick found that the microbial awakening is actually changing the structure of the Arctic and boreal food webs, that is, it’s changing the interconnected relationships between organisms and what they eat.
“What it means is that a food web that was in the past, supported by primary production in plants, is now supported by decomposition,” Manlick said.
Manlick and his team studied samples from small mammals collected at the Bonanza Creek Experimental Forest near Fairbanks over the last 30 years of warming. During that period, they determined that fungi were becoming a bigger part of the animals’ diets.
Manlick calls this a “browning” of the food web. In the past, most of the energy supporting small mammals like shrews and voles came from eating plants. Now, he said, for some species, most of that energy is derived from fungi.
“We can say, with very strong certainty, that fungi are becoming a really, really important player in terms of energy,” Manlick said. “If you look at a shrew in 1990, they were probably getting 40 to 50% of their energy from fungi. And now it’s like 90 to 100%.”
Manlick said there’s still a lot that scientists don’t understand about the ripple effects this new abundance of energy will have on northern ecosystems, which are rapidly transforming as a result of human-caused climate change.
Amanda Koltz, a University of Texas ecologist who co-authored the study, said it’s already understood that increased microbial activity as a result of permafrost thaw has global implications.
Decomposition in the soil releases carbon dioxide and methane into the atmosphere, which adds to the carbon emissions humans are already pumping out, speeding up global warming.
The world’s permafrost is estimated to hold twice as much carbon as is currently in the atmosphere.
“Even though these northern ecosystems — at least for folks down south — seem very far away and irrelevant, it’s not actually true, because what happens in the Arctic and in the boreal is really globally relevant,” Koltz said.
The Arctic is already warming four times faster than the rest of the planet due to climate change.
Manlick and his team have more research planned to study how the microbial awakening is impacting higher levels of the food web this summer.
Kavitha George is Alaska Public Media’s climate change reporter. Reach her at kgeorge@alaskapublic.org. Read more about Kavitha here.
