Abstract
Endemic and disjunct populations of vascular plants and cryptogams occurring in the Chic-Choc Mountains on the Gaspé Peninsula in eastern Québec, Canada, have been attracting botanists for over a century. Although controversial, these ancient mountains have been hypothesized to have been nunataks during the Wisconsin glaciation in part because they contain vascular plants that are not known to colonize nearby mountains with similar environments that were not thought to be nunataks. To determine whether there are lichen species that have the same pattern as the vascular plants, we examined the North American distribution of all the approximately 600 lichens known from the Chic-Chocs. Fifteen Arctic-alpine species were found to reach the edge of their southeastern North American range in the Chic-Chocs. Six of these species are not known to occur again for over 1000 km to the north. These results provide an additional layer of biogeographic knowledge about the unusual flora of the Chic-Chocs and lend some support to the hypothesis that the Chic-Chocs might have been nunataks during the last glacial period. Any Arctic-alpine species occurring in the Chic-Chocs are good candidates for monitoring the effects of climate change, but the 15 lichen species that reach their southeastern limit in this range might be the most vulnerable.
Highlights
Lichen communities are broadly shaped by bioclimatic regions such as Arctic-alpine, boreal, temperate, and tropical (Thomson 1984, 1997; Gowan and Brodo 1988; Brodo et al 2001)
To determine whether there are lichen species that have the same pattern as the vascular plants we examined the North American distribution of all the ca. 600 lichens known from the Chic-Chocs
Fifteen Arctic-alpine lichen species appear to reach their southern limit in eastern North America in the Chic-Chocs (Table 1; Figure 2)
Summary
Lichen communities are broadly shaped by bioclimatic regions such as Arctic-alpine, boreal, temperate, and tropical (Thomson 1984, 1997; Gowan and Brodo 1988; Brodo et al 2001). The temperature in the Arctic has had a mean increase of ~0.1 °C annually over the last 30 years, nearly twice that of lower latitudes (Dormann and Woodin 2002; Anisimov et al 2007; IPCC 2007; Kaufman et al 2009). Vegetative responses to this changing climate include an advancing tree-line and an increase in shrub density (Myers-Smith et al 2011; Elmendorf 2012; IPCC 2013). Arctic lichens may not have new areas to migrate to or enough time to adapt to the rapidly warming conditions, but the open high-Arctic and Arctic-alpine regions are expected to be refugia (Cornelissen et al 2001)
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