Antarctic Science

Biological Sciences

Primary succession of lichen and bryophyte communities following glacial recession on Signy Island, South Orkney Islands, Maritime Antarctic

Sergio E. Favero-Longoa1 c1, M. Roger Worlanda2, Peter Conveya2, Ronald I. Lewis Smitha3, Rosanna Piervittoria1, Mauro Guglielmina4 and Nicoletta Cannonea5

a1 Dipartimento di Scienze della Vita e Biologia dei Sistemi, Università degli Studi di Torino, V. le Mattioli 25, 10125 Torino, Italy

a2 British Antarctic Survey, NERC, High Cross, Madingley Road, Cambridge CB3 0ET, UK

a3 Centre for Antarctic Plant Ecology and Diversity, Moffat, DG10 9LB, UK

a4 Dipartimento di Biologia Strutturale e Funzionale, Università dell'Insubria, V. Dunant 3, 21100 Varese, Italy

a5 Dipartimento di Scienze Chimiche e Ambientali, Università dell'Insubria, V. Valleggio 11, 22100 Como, Italy

Abstract

A directional primary succession with moderate species replacement was quantitatively characterized on Signy Island in zones of a glacial valley corresponding to their age since deglaciation. A continuous increase in diversity and abundance of lichens and bryophytes was observed between terrains deglaciated in the late 20th century, to areas where deglaciation followed the Little Ice Age, and others thought to be ice-free since soon after the Last Glacial Maximum. Classification (UPGMA) and ordination (principal co-ordinate analysis) of vegetation data identified three different stages of development: a) pioneer communities, which rapidly develop in a few decades, b) immature communities developing on three to four century old terrains, and c) a climax stage (Polytrichum strictum-Chorisodontium aciphyllum community) developing on the oldest terrains, but only where local-scale environmental features are more favourable. Multivariate analysis including environmental parameters (canonical correspondence analysis) indicated terrain age as being the dominant controlling factor, with other environmental factors also exhibiting significant conditional effects (duration of snow cover, surface stoniness). These findings not only quantitatively verify reports of the rapid colonization of Maritime Antarctic terrains following recent climate amelioration and associated decrease in glacial extent, but also show how local-scale environmental resistance may slow or even prevent vegetation succession from pioneer to more mature stages in future.

(Received July 22 2011)

(Accepted November 03 2011)

(Online publication March 07 2012)

Correspondence:

c1 sergio.favero@unito.it

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