Are we bidding farewell to unique tundra in the Arctic?
15 October 2019
As temperatures continue to rise in the Arctic, it is likely that the area’s unique and diverse tundra will change, becoming home to a more uniform type of vegetation dominated by shrubs. As Lærke Søndergaard Stewart explains, such a change could cause additional disruption to the local and global climate
Most land in the Arctic is covered by tundra—composed of small, low-growing forbs (herbaceous flowering plants), grasses, mosses, lichens and occasional dwarf shrubs—that developed due to the permafrost and very short growth season.
The beauty of this landscape is unquestionable. The Arctic bluegrass shimmers like northern lights in yellowgreen, turquoise and blue-lilac colours. The northern catchfly points cheerfully with its bloated striped sepals, while the arctic bell-heather’s fine white bells collect the morning dew. The yellow marsh saxifrage shines in competition with the midnight sun, and the red-tipped lousewort stretches its flaming flowers toward the great open sky.
Somehow, these small, seemingly fragile flowers have adapted to survive in a climate where the annual average temperature is below zero, the soil is permanently frozen, and there is total darkness for up to six months of the year.
These plants, against all reason, underpin a whole ecosystem in the far North. White Arctic hares, playing Arctic foxes, buzzing insects, grazing muskoxen, small snow buntings and majestic snowy owls are just some of the species that depend on Arctic vegetation.
Threatening the survival of the Arctic's unique Tundra
This whole ecosystem is in danger as temperature rises. The rapidly changing climate does not affect only temperatures: the amounts of snow and rain are also changing, and the permafrost is becoming less stable. In turn, these conditions are causing the water content of the soil to change. Temperature, soil moisture and the amount of snow are all vital for the survival of tundra plants because each and everyone has adapted to grow under certain temperatures and snow and water levels. When these change, species that are adapted to the Arctic climate may not survive. Meanwhile, other species may expand their ranges northward.
So the question is: what will happen to the unique Arctic tundra as the climate changes? How will changing temperatures, snow and soil moisture affect the composition of the vegetation?
Searching for answers in one of the world's greatest national parks
Hoping to find answers to these questions, I made the long journey north several years in a row to one of the most deserted land areas on Earth: northeastern Greenland.
Here, the tundra extends across the world’s largest national park. Deep in the middle lies a small research station where international scientists are developing a much better understanding of all the components of an Arctic ecosystem and how they interact.
I spent several summers here collecting data on plant distribution, measuring the soil’s water content and temperature, and using data collected at the research station on snow distribution. Once home, I analysed all of these data and transformed them into statistical models.
Moving slowly from diversity to uniformity
The results show that changing climatic conditions will mean this area of northeast Greenland is no longer optimal for many of the unique species that currently live there. On the other hand, there will be optimal conditions for a few species of dwarf shrubs that can spread and outcompete the smaller herbs and grasses.
If the climate continues to change, it is likely that the unique and diverse Arctic tundra landscape will change to a more uniform landscape dominated by shrubs. Such a change will have a great impact on the local ecosystem and all of the species that live in the area. If this change is representative of other parts of the Arctic, it will lead to additional climate changes.
The structure of the plant communities influences the water balance, how the snow is distributed in the landscape, the permafrost, the amount of solar radiation that is reflected into the atmosphere, and how much is absorbed by the soil. All these factors together affect the climate.
A warmer Arctic—where the current diverse vegetation is taken over by dwarf shrubs—will not only lead to a world that is poorer in many unique species. It will also potentially reinforce climate change itself.
LÆRKE SØNDERGAARD STEWART recently finished her PhD in Arctic vegetation ecology at Aarhus University and teaches at the University of Southeastern Norway.