Arctic plants react to climate change in unexpected ways

“The Arctic is surprisingly diverse. Tundra ecosystems can pack tens of plant species into a one-square-metre plot,” said lead author Dr. Mariana García Criado from the University of Edinburgh. “Our study indicates that biodiversity can follow diverging trajectories in the rapidly warming Arctic.”

In the tundra, there’s no clear winner

Scientists studying plants in one of the most extreme environments on Earth say the Arctic is indeed changing under the impact of global warming – but not in a uniform way. Many locations saw new species flourish, while others lost biodiversity. Some changes include large increases in shrubs and grasses across the Arctic and declines in flowering plants – which struggle to grow under the shade created by taller plants. The study sheds light on how climate change is reshaping one of the world’s most fragile ecosystems.

Shrub expansion was associated with greater species losses and decreasing species richness at sites across the tundra biome. Credit: Petr Macek, BC CAS

Warmer temperatures are bringing in more species, but not everywhere. Shrubs are reshaping the Arctic ecosystem, but not universally. In other words, while the plant mix is shifting, the overall composition remains in flux. There are no clear winners or losers. The main drivers of these changes in plant diversity are warming temperatures and increased competition between plants. The results show how vegetation changes are an early warning signal that whole ecosystems might be about to change, with knock-on effects for animals, humans and the planet’s natural carbon storage systems. 

“Often when we think about climate change impacts on the planet we think about biodiversity loss, but in the temperature-limited tundra, climate change is multi-faceted. We’re seeing biodiversity shifts reshaping ecosystems in ways we don’t yet fully understand, making it even more urgent to track what’s happening and prepare for the consequences,” added Professor Isla Myers-Smith, a climate change ecologist at the Universities of Edinburgh and British Columbia.

The research, published in Nature, spanned 2,174 plots across 45 sites from the Canadian High Arctic to Alaska and Scandinavia. Scientists compiled more than 42,000 field records from 490 plant samples. They tracked over 2,000 plant communities between 1981 and 2022. A team of 54 researchers from 50 institutions collaborated on the project, part of the International Tundra Experiment (ITEX).

Key findings:

• More warmth, more plants: Plant diversity tended to be greater in warmer areas and the southern Arctic. For every 2 C increase in temperature, an additional species was typically found. However, long-term trends didn’t show a consistent increase or decrease, suggesting the relationship between warming and biodiversity is more complex than expected.
• Shrubs are reshaping tundra communities. In areas where shrubs increased, plant diversity often declined, particularly when tall shrubs crowded out smaller plants. However, other types of plants also play a role. Tundra communities dominated by flowering plants tended to support a greater variety of new species, highlighting the varied impacts different plants have on these environments.
• Most sites saw plant turnover and a changing mix of species. Warmer areas and places with stronger warming trends had more species come and go. However, the study did not find evidence that Arctic plant communities are becoming more similar to each other over time.

Publication:

García Criado, M., Myers-Smith, I.H., Bjorkman, A.D., Elmendorf S.C., ..., Macek P. (2025) Plant diversity dynamics over space and time in a warming Arctic. Nature. https://doi.org/10.1038/s41586-025-08946-8