Forest Ecology Research Group

Conference presentation – Successional processes in subarctic wetlands influenced by permafrost thaw

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Our MSc student, Mélissa Fafard, is in Switzerland presenting at the Faster, Higher, More? – Alpine and Arctic Flora under Climate Change Conference. Her talk is titled:  Successional processes in subarctic wetlands influenced by permafrost thaw.


Peatlands are often influenced by both autogenic (internal) and allogenic (external) influences. Through autogenic influences there is a natural unidirectional trajectory between wetland types, where a rich fen will transition to a poor fen and, finally to a bog. The aim of this study was to test whether allogenic factors, specifically climate change-induced permafrost thaw, could lead to the reversal of the typical autogenic successional trajectory. The sampling was done in the Northwest Territories, Canada, where lichens, vascular and non-vascular plants were identified in rich fens, poor fens and collapse scar bogs with different levels of hydrological connectivity. Species accumulation curves and richness indices show a marked increase in species richness with connection, although this increase is variable among wetland classes. Rich fens had the highest species richness and showed the most response to increased levels of connections, followed by poor fens and collapse scar bogs. Non-metric multidimensional scaling was used to examine patterns in community composition and structure and confirmed that each wetland type had a distinct community structure. While increased connectivity was typically associated with greater species richness, in collapse scar bogs this equated with the encroachment of fen species into the collapse scars suggestive of a role of allogenic successional processes. To examine this progression, hydrological and remote sensing data will be coupled to test
patterns of allogenic succession.

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