Mountaintops in Europe have seen a drastic increase in plant species over the past ten years, according to a new study. Researchers said the observed changes are “unequivocally linked to global warming” and could threaten the delicate, high-altitude species, which traditionally occupy these habitats.
The research was published on Wednesday in the journal Nature by a team of 53 scientists from 11 European countries. Led by Sonja Wipf from the Institute for Snow and Avalanche Research in Davos, Switzerland, the study examined over 300 summits in mountain ranges across the European continent, including the Alps, Pyrenees, Carpathians and other ranges.
Data spanning 145 years showed a significant rise in “plant species richness” on nine out of ten peaks – even on mountaintops extending into the Arctic Circle on Norway’s Svalbard archipelago. No peak studied showed a decrease in plant species.
“Across all summits, the increase in plant species richness has accelerated,” according to the study, with acceleration being “particularly pronounced during the past 20-30 years.”
During the decade 2007 to 2016, the number of plant species on the summits studied increased five times more than during the period 1957 to 1966.
Researchers looked into factors that could be responsible for the acceleration, such as changes in precipitation and nitrogen input or increased livestock grazing. They found that none of these factors could explain the increase in new plant species – the only explanation was temperature rise.
Although the scientists speculated about the potential impacts of the acceleration, their research did not explore whether the new species were displacing existing ones or by how much.
“Some of the species which have adapted to the cold and rocky conditions on mountain summits will probably disappear in the long term,” said Manuel Steinbauer, the lead author of the study. “They have nowhere else to go, and they can’t develop rapidly enough to be able to compete with the new arrivals, which are taller and more competitive under warmer climates.”
Steinbauer noted that local conditions affect the new species’ chances at survival. “The species that move upwards, often come from grassland above the tree line. But they can’t survive everywhere on the mountaintop, so it’s not certain that they will be a threat to all the existing species up there,” Steinbauer added. “The local soil conditions and micro-climates also play a role.”
The scientists did not look into how many additional species may begin to inhabit the mountaintops in the future, but said it is likely to be affected by future warming.
“Even though the existing species on mountaintops are not acutely endangered, the strong acceleration in the effects of global warming on plant communities on the peaks does give cause for concern, as we expect far stronger climate change toward 2100,” said Jens-Christian Svenning, an Aarhus University professor who was involved in the research.