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Alpine plants: persistent and endangered

Becoming increasingly rare: plants perfectly adapted to high alpine conditions. (c) G. Losapio and coauthors

Spiked rue, glacier buttercup, saxifrage: the habitat of such alpine plants is shrinking with the glaciers, as a recent study shows. In addition to climate change, mountain plants are also suffering from nitrogen deposition.

What will happen to the flora at high alpine altitudes when the last glaciers melt? This question was investigated in four glacier regions of the Italian Alps, the results of which were published in the journal Frontiers in Ecology and Evolution at the end of January 2021. According to the study, the disappearance of the glaciers would cause the extinction of up to 22 percent of the 117 plant species studied. Where retreating glaciers expose soil, pioneer plants initially settle, which actually leads to more species diversity in the short term, as study coordinator Gianalberto Losapio of Stanford University/USA explains. “It becomes problematic when the glaciers retreat further and further, because the plants can’t keep up this chase indefinitely.” Losapio’s team also observed an increasing competitive situation: “As soon as the glacier disappears, more aggressive species displace the pioneer plants.” That and the lost habitats at the base of the glaciers are likely causing this biodiversity loss. Plants such as spiked rue, glacier buttercup and some saxifrage species are particularly at risk. The study involved the University of Insubria, the University of Milan and the Museum of Science in Trento.

Nitrogen as an additional problem

Why high alpine plant species react to climate change with a time delay was also investigated by ecologist Sabine Rumpf in 2019 for a study by the University of Vienna and the Swiss Federal Institute for Forest, Snow and Landscape Research WSL. One of the reasons is that alpine plants are long-lived and remain in place when environmental conditions are no longer suitable. “We call this extinction debt. We know that the local plant will die sooner or later, but it’s still there,” said Rumpf, who is now conducting research at the University of Lausanne/CH. The disappearance of local occurrences does not mean these species will die out completely, she said, but without glaciers, “the habitat where these species can occur is just very much reduced.” In addition to the long-term effects of climate change, the researcher warns of direct effects such as nitrogen inputs from factories, intensive agriculture and automobile traffic. “What we do miles away in the lowlands has big impacts in the mountains, because that’s where the nitrogen comes back down through the atmosphere.” Mountain plants typically do very poorly with nitrogen, as Rumpf explains. “That means we’re selecting for plants from the lower elevations that will gain more territory over the alpine plants.”

 

Sources and further information:

www.wienerzeitung.at/nachrichten/wissen/klima/2091250-Wie-die-Blumen-der-Alpen-mit-den-Gletschern-verschwinden.html (en), www.frontiersin.org/articles/10.3389/fevo.2020.616562/full (en), www.nature.com/articles/s41467-019-12343-x (en), www.touringclub.it/notizie-di-viaggio/intervista-a-gianalberto-losapio-con-il-ritiro-dei-ghiacciai-un-quarto-delle/immagine/7/the-consequences-of-glacier-retreat-are-uneven-between-plant-species (it), www.greenreport.it/news/aree-protette-e-biodiversita/quasi-un-quarto-delle-piante-alpine-e-a-rischio-estinzione-per-la-scomparsa-dei-ghiacciai/#prettyPhoto (it)