In the last 30 years the plants native to the Alps have moved to ever higher altitudes and their survival niches have been reduced due to climate change; on the other hand, the alien species know how to resist better. For example, in the last 30 years the Bromus erectus has moved with a speed of about 3 meters per year and an alien species like the Sorghum halepense it moved at a rate of 4 meters a year. This is indicated by the Italian research, led by Lorendo Marini and Costanza Geppert, both of the University of Padua, and published in the journal of the United States Academy of Sciences (Pnas). Conducted in collaboration with Alessio Bertolli and Filippo Prosse, of the Rovereto Civic Museum Foundation, the research is based on the analysis of over 1,400 species, both native and alien, between 1990 and 2019.
The increase in temperatures also has a strong impact on the plants that live in the Alps because the warming pushes the various species to climb in altitude in order to have suitable environments available for survival. But this climb in search of colder temperatures obviously takes rather slow times for the plants, slower than the changes taking place, and therefore we are witnessing the gradual reduction of the liveability niches of many plants. Analyzing these changes over the last 30 years, the Italian researchers have verified that this upward translation does not occur in the same way for all species, the autochthonous plants in fact show a greater difficulty of survival than the alien plants, the species which over the years (due to introduction by man) have found space in the Alps but which were originally from other areas.
In particular, for autochthonous species there is in fact a more pronounced reduction at lower altitudes while alien species have a greater ease of adaptation to hot temperatures. A phenomenon, underline the authors, which should push to extend the conservation policies of the native flora also in low-altitude areas where there is generally less attention to the problem and at the same time a stronger competition from alien species .
“In ecology it is rare to be able to examine data with good spatial and temporal resolution. In this study we were able to analyze the distribution changes of more than one million records of 1,479 alpine species over a period of thirty years,” notes Geppert, from the Department of Agronomy, Animals, Food, Natural Resources and the Environment of the University of Padua. Marini, who coordinated the study, notes that “the rapid loss of specific distribution areas of rare plants has occurred in areas where human activities and environmental pressures are high. This – he continues – suggests that we should also protect some downstream areas and not just the more remote high-altitude areas. What we did was measure the ability of plant species to compete, even with humans. Alien plants in disturbed conditions – for fertilization, removal of the resident vegetation for the construction of a house, a road or a parking lot – they are very quick to grow and exploit the resources present, subtracting them from the other native species.Our study has shown that it is precisely in the most anthropized and disturbed areas that alien plants are particularly adept at competing with other species”.
For Prosser and Bertolli “the open areas risk disappearing because in the steepest and most uncomfortable areas they are being abandoned, while in the flat areas near the roads they are subject to increasingly excessive fertilization and grazing, which lead to a trivialization of the floristic component. The danger it is losing truly unique and precious species for the biodiversity of our Alps”.
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