With temperatures on the rise, the prickly pear cactus is wreaking havoc in the Swiss Alps, pushing out native flora in the region.
Environmentalists in Switzerland’s Valais region are concerned about the rapid spread of an invasive plant species in the area: the prickly pear cactus. The cacti have dominated nearly one-third of the available land in the area, wreaking havoc on native species and posing a worrisome ecological problem.
With global temperatures on the rise, snowfall in the Alps, which would have made conditions inhospitable for the plants, is now sparse — and the cacti are reaping the benefits.
The plants are native to hot, arid environments in the Americas, so the Swiss Alps should be the opposite of their ideal climate. Typically, the prickly pear cactus thrives in temperatures over 100 degrees Fahrenheit (38 degrees Celsius), but it can survive in temperatures as low as five degrees Fahrenheit (-15 degrees Celsius).
The cacti, originally brought to Europe by merchants and explorers from the Americas more than 200 years ago, were unable to withstand the frigid climate of the Swiss Alps for centuries. With temperatures on the rise, however, the invasive species is starting to take root.
According to a study by Nature Climate Change, the Swiss Alps have experienced a 5.6 percent reduction in snowfall per decade in the last 50 years. Meanwhile, the duration of the snowpack on the ground has shortened by 36 days.
In nearby areas, the effect of rising temperatures is apparent and economically frustrating. Ski resorts have been struggling to keep business. Many places are turning to indoor ski structures or using fake snow machines to stay open.
While ski resort owners struggle with the effects of rising temperatures, the cacti flourish.
According to The Guardian, the municipality of Fully, a town in the Rhone Valley near the border of Switzerland and France, stated in a recent press release: “A lover of dry and hot climates, this invasive and non-native plant is not welcome in the perimeter of prairies and dry pastures of national importance.”
In Valais alone, the cacti currently make up a minimum of 25 percent of the low vegetation cover. Yann Triponez, a biologist who works in Valais’ nature protection service, stated that the cacti are spreading and are believed to be able to “occupy one-third of the available surface” in the region.
Environmentalists worry that the cacti may cause major ecological issues beyond the area, as well. The plants have already proliferated other nearby areas, including parts of Italy.
When asked why the cacti pose such a strong ecological threat, Triponez responded, “When you have these cacti, nothing else grows. Each pad covers the soil and prevents other plants from growing through.”
Peter Oliver Baumgartner, a retired geology professor at the University of Lausanne in Switzerland, added that nine species of the cacti are present in Switzerland. Out of those nine, four are particularly invasive and resistant to lower temperatures.
“These [four] species bear -10 Celsius or -15 Celsius without any problem,” Baumgartner told The Guardian.
These four species of cacti have spread well in the neutral and acidic soils in the Rhone Valley, and researchers and officials are concerned not only about the effect they will have on protected plant species, but also about how difficult it may be to eradicate them.
The municipality of Fully announced its cactus uprooting campaign in late 2022 alongside an awareness initiative for residents and tourists. Officials expect the campaign to be long and arduous, as the cacti are notoriously difficult to remove.
Researchers note that the cacti breed quickly, are resilient to drought and trampling, and recover quickly after being uprooted. The cacti even grow back in the same spot they were removed from, causing researchers to doubt whether eradication is even possible.
Years of unsuccessful uprooting campaigns in the area have only strengthened researchers’ beliefs. In 2022, after uprooting groups of cacti and piling them up in a forest in Fully, authorities were astounded when the cacti did not rot or compost as they expected — but instead began thriving.
“We can restrict them,” Baumgartner said. “But I don’t think we can get rid of them.”