Climate change: newcomers displace alpine vegetation

Alpine vegetation in the Dolomites endangered

Dolomites summit © GLORIA
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The first effects of global warming are already visible on the alpine vegetation: as a new study shows, forest trees, forest border types and types of lower altitudes are already penetrating higher altitudes. Small-sized alpine plants are thereby displaced.

Brigitta Erschbamer, professor of botany at the University of Innsbruck and head of the project, and her team researched the changes in alpine vegetation on four mountain peaks in the Dolomites. The researchers mapped the plant world of all the peaks in the Trentino-Alto Adige region in 2001, then again in 2006. The result: the proportion of new plant species on the highest peaks (2, 757 meters and 2, 893 meters) is ten or nine percent. The newcomer to the lower summits, however, was much lower at three and one percent.

"Originally, we expected a higher number of newcomers, especially at the lowest peak. But it is obvious that there are probably almost all niches occupied, and new species hardly find any growth opportunities, "explains Rekbamer.

Newcomers climb peaks

The newcomers, apart from those on the highest peak, are plants from the montane and subalpine stages. "Plants that have so far been below the current tree line, move upwards and displace the alpine plant species, " says the South Tyrolean botanist. Among the newcomers in the upper alpine stage (2, 757 meters) were mainly larch, dwarf juniper, lady's mantle and Common sedge. At the highest summit, species of the alpine and nivalen stage were added, such as single-head herb, Dolomite devil's claw or dwarf valerian.

Significantly more young trees in higher elevations

At the lowest peak, a significant increase in young trees (for example larch and stone pine) as well as in aggressive, tall grasses and dwarf shrubs such as cranberry could be observed in the relatively short period of five years. display

"If this development continues in the next few years, it is especially on this very species-rich summit - 159 plant species in the top ten altimeters - to expect a strong loss of species, since a shading by the young trees of the ancestral, light-requiring alpine plant species not "At the higher peaks, however, a further increase in species numbers can be expected, since the areas are still very patchy, and the competition between the species still should not play such a big role as at the lowest peak .

Soil type decides with

EntwicklungDevelopment is very dependent on soil formation: on raw soils, the more demanding species from lower elevations are difficult to cultivate, so at higher altitudes above l For a longer period of time alpine species dominate, "says the researcher, emphasizing the importance of a long-term observation:" We do not know whether and for how long the species found in 2006, such as dwarf junipers or larch, will be found 2, 757 meters sea level can hold. Continuous repetition of recordings every five to ten years is therefore very important.

Long-term study should clarify fate of alpine vegetation

In the relatively untouched high mountain regions, floristic changes can be attributed primarily to climate change. At regular intervals, therefore, the vegetation surveys should be repeated at each summit. "Since vegetation is lagging behind climatic changes, five years of observation time are too short to find truly conclusive answers to the questions of the fate of alpine vegetation", stresses Erschbamer. Long-term, however, high-alpine plant species may be in demand and may even become extinct as they are pushed further up.

The background of the global GLORIA project is to investigate the biodiversity of the high mountains and their changes in the long term with the help of a dense observation network. In total there are already 47 GLORIA project areas. The overall management of the worldwide project lies with Professor Georg Grabherr from the Institute of Ecology and Conservation Research at the University of Vienna.

(University of Innsbruck, 20.02.2007 - NPO)