Climate changes in Alpine flora

'Heat and drought can trigger persistent changes in Alpine flora'

UAntwerp researchers study impact of warming and drought in the Alps

Alpen
A single weather extreme has far-reaching consequences. Damage to alpine vegetation in the short term, but also long-lasting legacy effects that can alter the appearance of alpine meadows for years. That is the conclusion of a team of Antwerp and Swiss researchers led by ecologist Hans De Boeck.

The summer of 2018 was exceptionally warm and dry in large parts of Europe. Again. This was not only true in the lowlands, but also in the mountain regions. While tourists rejoiced, glaciers continued their retreat. Also the plants high up in the mountains are affected by the extreme weather.

Together with Swiss colleagues, researchers from the University of Antwerp studied what impact heat waves and drought have on alpine vegetation, both in the short and longer term. To this end, the researchers exposed sections of alpine grassland to a 17-day period of extreme heat by temporarily transporting them from high in the mountains (Furka Pass) to deep in the Rhone valley. “This ‘heat wave’ was then combined with either normal precipitation or drought”, lead researcher Hans De Boeck (UAntwerp) explains. “The immediate effects were clear: while the plants grew normally when they had enough water, a high degree of plant stress was observed when the heat coincided with a drought period.”

Grasses on the rise
The researchers returned the following years to see how fast the alpine grassland could recover from this stress. “It appears that even two years after the extreme, its effects were still obvious. Though growth returned to normal levels, more bare soil was present and the number of flowering plants had decreased, with the vegetation becoming more ‘grassy’. “These grasses survived the extreme weather conditions better, and were able to translate this initial advantage into a lasting increase in dominance. When confronted with a new hot drought, this ‘new’ grassland may prove to be more resistant than the original.”

Whether alpine meadows will indeed become less colourful in the future as flowering plants disappear, depends on a number of other factors, but it is clear that climate extremes can have significant and long-lasting impacts, also high up in the mountains. These results have now been published in the scientific journal Frontiers in Plant Science.