Taller tundra plants are taking over the warming Arctic

27 Sep 2018

One of the tundra sites examined by researchers. Image: Dr Anne Bjorkman

Plants in the Arctic are growing taller because of climate change, according to a recent study.

The Arctic tundra has traditionally been the domain of low-growing grasses and dwarf shrubs. The harsh conditions mean the plants generally cling close to the ground and grow to only a few centimetres high.

The landscape is changing though, with new, taller plant species slowly invading, as well as native species growing larger.

An international group of almost 130 biologists published a study in the journal Nature, encompassing nearly 120 tundra sites. The sites were generally located in Arctic regions of Alaska, Canada, Iceland, Siberia and Scandinavia.

Co-author Dr Anne Bjorkman, who now works at the Senckenberg Biodiversity and Climate Research Centre, conducted the study at the iDiv research centre in Germany, the University of Edinburgh and Aarhus University.

Climate change sees taller tundra plants

She said that the increase in plant height was “not just in a few sites, but nearly everywhere”. Researchers say that climate warming is the culprit behind the creeping height increases.

As well as the increase in stature plants native to the tundra are exhibiting, taller species of different plants are spreading across the southern parts of the Arctic. Vernal sweetgrass, a plant commonly found in lowland Europe, is now growing at sites in Sweden and Iceland.

The researchers assessed the interrelationships of temperature, soil moisture, and key traits of the form and function of plants. They also looked at plant height and leaf area, leaf nitrogen content, woodiness, evergreenness, and other characteristics.

A sensitive ecosystem

Bjorkman said: “Rapid climate warming in the Arctic and alpine regions is driving changes in the structure and composition of plant communities, with important consequences for how this vast and sensitive ecosystem functions.

“Arctic regions have long been a focus for climate change research, as the permafrost lying under the northern latitudes contains 30 to 50pc of the world’s soil carbon.

“Taller plants trap more snow, which insulates the underlying soil and prevents it from freezing as quickly in winter.” She added that a boost in taller plants could accelerate the thawing process of the frozen carbon bank, leading to an increase in the release of greenhouse gases.

Soil moisture plays a part

Dr Isla Myers-Smith of Edinburgh University’s School of Geosciences co-led the study. She said that quantifying the link between the environment and plant traits is vital to understanding the consequences of climate change.

According to Myers-Smith, the research shows that soil moisture plays a much larger part in altering plant traits than previously thought. The team also found no evidence that the increase in taller species is currently leading to a decline in shorter species.

“This is the first time that a biome-scale study has been carried out to get to the root of the critical role that plants play in this rapidly warming part of the planet,” Myers-Smith said. The scientists said that water availability should be considered just as much as temperature when monitoring plant habitats in the tundra areas.

Ellen Tannam was a journalist with Silicon Republic, covering all manner of business and tech subjects