Alpine plants at risk of extinction as glaciers disappear

A view of Going-to-the-Sun Mountain through melting snow and ice at the origin of Reynolds Creek near Logan Pass in Glacier National Park, Montana. (Joe Giersch/USGS)

(CN) — Retreating glaciers expose new terrain for plants to grow, but this alters the inhabitability and diversity of so-called “downstream ecosystems” — so much so that alpine plants often used in liqueurs and medicines face extinction.

Nearly one in four alpine flower species in the Alps face extinction as glaciers melt, according to a study published in the journal Frontiers in Ecology and Evolution.

“Our results indicate that plant diversity will ultimately decrease once the glaciers disappear — and up to 22% of the species we analyzed may locally disappear or even go extinct once the glaciers are gone,” says lead author Dr. Gianalberto Losapio, a biologist at Stanford University. “We show that ‘not all species are equal before global warming’ and that there are some species benefiting from global warming while others… suffer.”

For alpine flowers, time is of the essence. Global warming is causing rapid glacial melt, with some scientists predicting that alpine glaciers could shrink by as much as 90% in 2021.

Global warming shifts the function of local ecology from facilitation to competition, with “pioneer” species that quickly colonize the new ground giving way to other species.

Using geological records, Losapio and his collaborators reconstructed the positions of four glaciers in the Italian Alps, allowing them to approximate the age of downstream communities. The scientists then combined this data with their own contemporary survey of 117 plant species and analyses of local environmental conditions to create computational models that calculate how plant distribution had changed over the past five thousand years.

The computational models Losapio and his colleagues created also forecasted the effects of future glacier retreat.

Glacier buttercup, Ranunculus glacialis, in front of the Rutor glacier, Italy. (Photo courtesy G. Losapio and co-authors)

Their findings indicated shifts in plant community interactions, with competitive species prevailing over time while some cooperative species, such as Artemisia genipi, declining within a century despite being among the first plants to colonize newly exposed terrain.

According to the study, glacial retreat will affect half of all local species in the Italian Alps, with 29% flourishing in the aftermath, including alpine sedge, while 22% of alpine flower species will be imperiled, including the glacier buttercup.

“At the local scale, soil carbon enrichment and reduction of (topographic) disturbance positively contribute to distribution patterns in 66% of the species, indicating a strong signal of environmental filtering,” the study finds.

To address uncertainty in the calculated dates of older plant communities, researchers used alternative methods to achieve similar estimates. Also, the scientists point out that their findings do not account for the role of evolution, which means that some species likely adapted to changing conditions in the past. But given the unprecedented rate of current glacier retreat, there is little time for such adaptations now.

This study contributes to the United Nations’ efforts to understand the mechanisms of biodiversity loss and promote conservation and sustainable management of threatened species and ecosystems. Losapio said he hopes the study helps conservationists and park managers to mitigate and anticipate the consequences of glacial melt on the Earth’s ecosystems.

“Plants are the primary producers at the basis of the food web that sustains our lives and economies, and biodiversity is key to healthy ecosystems — biodiversity also represents an inestimable cultural value that needs to be properly supported,” Losapio said.