Usnea antarctica, an important Antarctic lichen, is vulnerable to aspects of regional environmental change
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Studies of cryptogam responses to climate change in the polar regions are scarce because these slow-growing organisms require long-term monitoring studies. Here, we analyse the response of a lichen and moss community to 10 years of passive environmental manipulation using open-top chambers (OTCs) in the maritime Antarctic region. Cover of the dominant lichen Usnea antarctica declined by 71 % in the OTCs. However, less dominant lichen species showed no significant responses except for an increase in Ochrolechia frigida, which typically covered dying lichen and moss vegetation. There were no detectable responses in the moss or associated micro-arthropod communities to the influence of the OTCs. Based on calculated respiration rates, we hypothesise that the decline of U. antarctica was most likely caused by increased net winter respiration rates (11 %), driven by the higher temperatures and lower light levels experienced inside the OTCs as a result of greater snow accumulation. During summer, U. antarctica appears unable to compensate for this increased carbon loss, leading to a negative carbon balance on an annual basis, and the lichen therefore appears to be vulnerable to such climate change simulations. These findings indicate that U. antarctica dominated fell-fields may change dramatically if current environmental change trends continue in the maritime Antarctic, especially if associated with increases in winter snow depth or duration.
KeywordsCO2 Gas fluxes Micro-arthropods Snow Usnea antarctica Winter
We are very grateful for the logistical support provided by the British Antarctic Survey. We thank Mark van de Wouw and Simon Hernimon for their help in establishing this experiment in the field. Special thanks to Roger Worland for managing the micro-climate logging system for many years in our absence. This study was initiated through financial support by the Netherlands Polar Programme (NPP-NWO 851.20.016), and SB was supported by an Antarctic Science Bursary for the 2013/2014 field season. PC is supported by NERC funding to the BAS core ‘Biodiversity, Evolution and Adaptation programme’. This work also forms an output of the SCAR programme ‘State of the Antarctic Ecosystem’.
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