Climate change is having a more profound effect on alpine vegetation than at first anticipated, according to a study carried out by an international group of researchers and published this week in the journal Nature Climate Change.
The research, the first ever pan-European study of changing mountain vegetation, was led by scientists from the Austrian Academy of Sciences and the University of Vienna, and also included scientists from the Centre for Ecology & Hydrology (CEH).
In total, biologists from 13 different countries in Europe analysed 867 vegetation samples from 60 different summits sited in all major European mountain systems, including four summits in the Cairngorms in Scotland. Samples were taken first in 2001 and then again just seven years later in 2008.
The researchers found strong indications that, at a continental scale, cold-loving plants traditionally found in alpine regions are being pushed out of many habitats by warm-loving plants.
“We expected to find a greater number of warm-loving plants at higher altitudes, but we did not expect to find such a significant change in such a short space of time,” said Michael Gottfried from the Global Observation Research Initiative in Alpine Environments (GLORIA) programme which coordinated the study.
“Many cold-loving species are literally running out of mountain. In some of the lower mountains in Europe, we could see alpine meadows disappearing and dwarf shrubs taking over within the next few decades,” he warned.
The study, which is the largest and most comprehensive of its kind in the world, confirmed that there is a direct link between growing summer temperature and the shift in alpine plant composition. “While regional studies have previously made this link, this is the first time it has been shown on a continental scale,” said Gottfried. This phenomenon, which the GLORIA researchers have called thermophilization, has now been measured and quantified for the first time and is expressed by the researchers as a thermophilization indicator.
All 32 of the study’s authors used exactly the same sampling procedures and returned to the same sampling sites, thus enabling a pan-continental comparison to be made for the first time. “We hope that our thermophilization indicator could be used by other research groups around the world and enable a global comparison,” said Harald Pauli, GLORIA’s network coordinator.
The research also showed that the effect is independent of altitude (it is happening at the tree line as well as on high mountain peaks) and latitude (the effect is seen in northern countries such as Scotland as well as southern mountain ranges such those on Crete).
Our work shows that climate change affects even the outer edges of the biosphere,” said Georg Grabherr, chair of the GLORIA programme. “The thermophilisation of alpine life zones can never be controlled directly. Adaptation strategies are not an option and we must concentrate on mitigating climate change in order to preserve our biogenetic treasure.”
The four summits sampled in Scotland are all part of the Environmental Change Network’s long-term monitoring site, ECN Cairngorm, which is coordinated by CEH on behalf of a consortium that includes Scottish Natural Heritage, the Natural Environment Research Council and the James Hutton Institute.
The Cairngorm catchment is in a pivotal position as its valuable long-term data is not only relevant to this alpine mountain study, but is also used as a research site for Arctic studies.