Temperatures at Europe’s highest points are rising, a regional reflection of a globally widespread warming phenomenon. As a result, the plant communities that live on mountain summits are also hosting increasingly many species associated with warmer climates.
It would be expected that warming would transform the vegetation communities of European alpine regions in almost the same way and at the same pace, with an increased abundance of heat-adapted or thermophilic species. But a group of scientists says that changes are not the same in all places.
“Our data clearly show that the vegetation on European mountain summits is changing and that heat-associated species are becoming more common,” explains Johannes Hausharter, from the University of Vienna (Austria).
However, the first author of the article reporting this discovery says that “the rate of these changes does not seem to depend solely on the rise in temperatures.”
The team considers that this study demonstrates not only the complexity of the transformations taking place in European alpine vegetation, but also that the effects of climate change, even in ecosystems as sensitive as the mountain summits of Europe, are subtler than one might think.
By analysing data from more than 700 sites across 53 mountain summits, over a 21-year period, the researchers argue that the link between rising temperatures and changes in vegetation continues to be limited to a local level. In other words, Alpine plant communities do not respond uniformly to the temperature rise in Europe, a response that depends heavily on local conditions.
“The response of Alpine vegetation to climate change depends not only on how many degrees the temperature rises, but also on the prior presence, or not, of other species associated with warmer climates,” details Stefan Dullinger, the lead co-author of the study.
In areas whose surrounding environment already had more species associated with warm climates, the proportion of these plants in the monitored areas increased more significantly over the study period than in zones where the surrounding environment had a lower abundance of these species.
Although they say that local climate impacts on plant communities vary from mountain summit to mountain summit, the scientists acknowledge that climate change is the main cause of the changes they observed over two decades of monitoring.
“Greater warming tends to mean more heat-associated species, but each summit reacts slightly differently,” notes Hausharter.
