Origin of the southernmost Arctic tundra of continental North America

The Arctic tundra extends beyond the treeline north of 58°N in eastern North America and north of 66°N in western North America and Eurasia. A marked exception to this distribution is the azonal tundra situated as far south as 54°30′–45′N, in the Pointe-Louis-XIV area (JABA), along the fast-rising coasts of James Bay–Hudson Bay. The unusual position of JABA calls into question the influence of climate as the main causal factor for its existence....