How climate change leaves Arctic caribou out in the cold
Competitors move in when shrubs start to grow in habitat: researchers
University of Alberta biologist Isla Myers-smith and her colleague were taking down their research camp in the Ruby Mountain Range when a snowstorm with winds of near hurricane force blew down their tent and sent their electric generator tumbling down a hillside.
For nearly three days, Myers-smith and Helen Wheeler hunkered down, eating what little food they had and watching nervously as the batteries of their satellite phone got weaker and weaker.
Hungry and uncomfortable, they couldn’t even sleep because their battered tent was constantly flapping in the wind.
Realizing from experience that such snowstorms can last for weeks in the Yukon, Myers-smith began wondering what their fate would be after spending several months in the wilderness.
“I was never so relieved when the weather cleared up long enough for the helicopter to come in and get us,” says Myers-smith. “It was nice to get out of there before winter set in.”
This was Myers-smith’s first year on a long-term study that University of Alberta scientist David Hik is conducting on the rapidly changing landscape of the alpine and tundra environment in the Yukon.
Up until then, most everyone knew that snow cover, cold temperatures and high winds come early and often to the Yukon, which is why much of the Arctic and sub-arctic world is covered with lichens, mosses and other small plants that tend to grow low or horizontally along the frozen ground.
It’s also why these alpine and tundra environments traditionally favour caribou over deer and Arctic hares, Arctic fox, pikas, ground squirrels and marmots over other smaller mammals that can’t handle the extreme cold.
But the latest work by Myers-smith, Hik and 30 other researchers from 10 countries in the world suggests that sizable chunks of this alpine/ tundra world are being taken over by shrub cover that is increasingly crowding out those plants that many Arctic animals depend on.
“Climate warming may well be a reason why this is happening,” said Myers-smith, who is the lead author of a paper published recently in the scientific journal Environmental
Research Letters. “But snow cover, nutrient availability and interactions with other plant species may also be important.”
An increase in shrub growth may not sound serious when compared to the advance of trees such as spruce, which some scientists believe are moving higher up in the alpine country and closer to the Arctic coast as the climate warms.
But shrubs such as alder, willow, dwarf birch and creeping juniper grow a lot faster than trees and they shade out sunshine that lichens, mosses and other alpine and tundra plants need to thrive during a growing season that is often measured in weeks rather than months.
“Shrubs also trap snow, which insulates soils in the winter, and shades soils in the summer,” says Myers-smith.
“Research has shown that soil in shrub-free zones can be almost a cold as the air above it. But that same soil that lies beneath shrubs in winter can be up to 30 degrees warmer than the air temperature. This insulating and cooling can alter soil temperatures, nutrient cycling and permafrost thaw.”
“Shrubs also seem to do best in a landscape that is increasingly becoming more disturbed,” she says. “The darkening of the surface associated with shrubs growing above snow could also accelerate snowmelt and cause regional warming.”
Forest fire experts and climatologists such as Mike Flannigan of the University of Alberta are increasingly turning their attention to this world where there are no trees. The proliferation of woody shrubs could conceivably increase the potential for future tundra fires such as the one that burned 600 square kilometres of tundra in Alaska in 2007, putting as much carbon into the atmosphere as the entire tundra world can store in a year. Woody shrubs can produce a lot more fuel for wildfires than most tundra plants.
The research that Myers-smith and her colleagues are doing can be painstakingly slow, often conducted over several years in a world that is not always welcoming to humans. Mosquitoes and wild weather make the fieldwork work extremely trying and occasionally dangerous.
While snow and wind storms are common, there are also grizzly bears, polar bears and even thunderstorms to worry about.
Several years ago, Myers-smith was working with colleagues in Alaska when a violent thunderstorm moved in. They knew they were in serious trouble when their hair stood on end from the static electricity produced by the lightning.
“It got to the point where I could feel this intense pressure behind my eyes,” says Myers-smith. “Then I started hearing what I thought was the sound of a cricket. ‘What kind of cricket lives up here in Alaska I thought?’ ”
Myers-smith took off her sunglasses and saw sparks from static electricity bouncing from one arm of the glasses to the other.
For some young Arctic scientists, fieldwork in remote areas can be overwhelming. More than one grad student from a Canadian university has had to be flown out from a remote camp, or given time off to deal with the stress that comes with the job.
Being the daughter of two university scientists may be the reason why Myers-smith is more melancholy than relieved when the field season ends. Her mother is a professor emeritus at the University of British Columbia and her father, who died in 2005, was an ornithologist with a good deal of field experience in the Far North. He worked in the Yukon with Hik, Myers-smith’s PHD supervisor.
“I made my first trip north to the Yukon with my dad when I was just nine years old,” she recalls. “That’s when I first fell in love with this part of the world.”
As much as the climate change debate has fizzled in recent years, Myers-smith is absolutely certain that investment in the kind of research she does will pay dividends.
“Climate change research in the North will help us to understand how our world is changing,” she says.
“It will also help us understand where the change is happening most rapidly. Ecologists can help us to identify when we can intervene to better manage a wildlife species or restore a disturbed area, and how ecosystems will change in the future so that we can adapt to the new conditions.
“Sometimes a small study at one location can identify an unconsidered factor that will go on to have big repercussions for our understanding of how ecosystems work.
“You can’t always predict when or where the exciting findings will happen, so we need to keep supporting the basic research and we also need to get together and share our data from different sites and different species to start build a more complete picture of the ecosystems we are studying.”