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Plant Sociology numero 53 (1)

pag. 45-54: Vegetation outlines of a debris-covered glacier descending below the treeline

D. Tampucci1, C. Citterio1, M. Gobbi2, M. Caccianiga1

1Department of Biosciences, University of Milan, Via Celoria 26, I-20133 Milano, Italy.

2Department of Invertebrate Zoology and Hydrobiology, MUSE - Museo delle Scienze, Corso del Lavoro e della Scienza 3, I-38123 Trento, Italy.

doi: 10.7338/pls2016531/03

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abstract

Debris-covered glaciers are glaciers with the ablation zone covered by a debris layer, which are able to persist below the treeline and to support plant life. These landforms are increasing on many mountain regions of the world as consequence of climate change, providing new habitat for plant colonization, but their vegetation features are still little known. Our aim was to describe the vegetation of an alpine debris-covered glacier descending below the treeline (Belvedere: Western Italian Alps) and compare it with those of the adjacent iceless moraine and stable slope. Our hypothesis was that plant community of the supraglacial debris differs from those of the surrounding landforms for the presence of cold-adapted species. Data were collected by phytosociological method performing 45 relevés of 25 m². Plant communities were compared by a cluster analysis based on the presence/absence species matrix; species relative frequencies for each landform were calculated. The cluster analysis clearly separated three plant assemblages, each corresponding with one of the investigated landforms. Unlike the iceless moraine, debris-covered glacier stands out for the presence of cold-adapted species typically widespread in the alpine and nival belts (e.g. Poa laxa and Cerastium pedunculatum), allowing them to survive below their normal altitudinal distribution, where the stable slopes host subalpine woodlands and shrublands.

keywords

alpine flora, alpine vegetation, Belvedere glacier, climate change, moraine, refugia