Invasion of the Shrubs
At a whopping metre high, Günther is a giant. An Arctic tundra willow, he’s a shrub lovingly named because in 2014, after years of work on Qikiqtaruk (Herschel Island), he was the tallest plant that University of Edinburgh scientist Isla Myers-Smith had ever seen. He’s also a harbinger of a green invasion: shrubs like birch, willow and alder are creeping their way polewards as the climate warms—and shoving aside weaker tundra-dwellers. How will Günther and co.'s northward march change the Arctic world? Scientists are still leafing through the data—but here’s who they think might be the winners and losers in the battles ahead.
Bigger: Following their noses, willow-eating moose are expanding their range northwards along with the shrubs. (Watch out Günther!)
Louder: Shrub-nesting songbirds like bluethroats may thrive as they find more places to nest and eat (bugs like shrubs too). Birds like the bristle-thighed curlew that rely on more open tundra may not fare so well.
Faster: You might say shrubs are spreading like wildfire. Frequent shrub fires were a fact of life in the Arctic’s distant past, as revealed from up to 14,000-year-old pollen and charcoal layers preserved in lakes.
Slower: Lichen is likely to lose out as shrubs crowd its sun, space, and food. A quick word on lichens: they aren’t mosses or even plants, but a symbiotic partnership between algae or bacteria and fungus, eking out a living from rock minerals, air, water and sunlight. It’s no surprise they grow only a few millimetres every year—slowpokes compared with Günther’s marathon sprint of 20cm in just one summer.
Pickier: Lichen-loving caribou will see their preferred food crowded and shaded out—and no one
knows whether they’ll learn to love the newcomers.
Hungrier: Arctic ground squirrels prefer open habitats where they can spot potential predators. More shrubs may mean more time looking for danger and less time chowing down.