Our directory of things of interest

University Directory

The bizarre case of Arctic ‘shrubification’

A caribou grazing in Alaska A caribou grazing in Alaska Shutterstock
08 Mar
2018
Scientists discover how shrubs are dominating the Arctic tundra

The landscapes of the Arctic tundra are changing dramatically. Spurred by global warming, low grasses and sedges are being taken over by thick, woody shrubs, some of them growing as tall as a person. Scientists at the University of Minnesota have discovered the key cause of this ‘shrubification’ – June temperatures.

The shrubs grow in rings, similar to trees, though at a tiny scale. A cross section of these growth rings can be measured against historical weather patterns to determine when a plant is growing fastest, and why. By looking at 20,000 individual shrub rings from the North Slopes of Alaska, the University of Minnesota team could see that the rings grew the most during warmer Junes. In fact, other factors didn’t even get a look in.

‘It was a surprising result,’ says Daniel Ackerman, the PhD ecology candidate who led the study. ‘Other variables, including temperatures during the rest of the growing season in July and August, barely had an impact on shrub growth.’ As subsequent June months are predicted to get warmer, ‘we can expect shrubification to continue throughout northern Alaska,’ says Ackerman.

164643 webConcentric growth rings (Image: Ackerman)

The transition to more shrubby landscapes is predicted to make life more difficult for Arctic species. It particularly impacts caribou herds, as shrubs have been observed to replace the lichen and other delicate tundra plants that they feed on. In fact, many scientists believe the greening of the Arctic is a foremost issue in relation to the mammals’ major decline. Meanwhile, some species may make use of a shrubbier ecosystem. ‘It seems like larger shrubs will benefit animals such as moose and ptarmigan, while others, such as caribou, could be harmed,’ says Ackerman.

geo line break v3

Free eBooks - Geographical Newsletter

Get the best of Geographical delivered straight to your inbox by signing up to our weekly newsletter and get a free collection of eBooks!

geo line break v3

Related items

NEVER MISS A STORY - Follow Geographical on Social

Want to stay up to date with breaking Geographical stories? Join the thousands following us on Twitter, Facebook and Instagram and stay informed about the world.

More articles in NATURE...

Wildlife

Not your usual tune: translating spider's silk into sound could…

Oceans

Millions of oysters have been rescued from the struggling shellfish…

Climate

History is littered with examples of fungi helping to digest…

Geophoto

The streets of Philadelphia are home to a small and forgotten…

Geophoto

When photographer Matthew Maran first snapped a fox he had…

Wildlife

Coloradans have voted to reintroduce grey wolves to the state

Energy

Covid-19 provides an opportunity to re-assess the supply chains of…

Geophoto

Andrea DiCenzo is a photojournalist, who has covered conflicts for…

Oceans

Field observations of corals around the world reveal that not…

Climate

The Great Plains of the USA are once again getting…

Climate

Attempts to build a digital twin of the Earth could…

Oceans

Food systems will need to change as the global population…

Wildlife

Zoos do a lot more than welcome excited visitors; closures…

Oceans

 BluHope is back with a day of webinars to promote…

Wildlife

WildEast, a grassroots community initiative, is encouraging volunteers to commit…

Wildlife

With growing global awareness of the risks of hunting and…

Climate

Researchers have identified the extent of microplastic contamination throughout the…

Wildlife

The Thames Estuary has long been home to heavy industry,…