Microhabitat Preferences of Dactylina arctica and D. beringica on Pingos in Northern Alaska

Walker, Marilyn

The distributions of Dactylina arctica (Richards.) Nyl. and D. beringica Bird & Thoms. were examined on pingos (ice-cored mounds) on the Alaskan Arctic Coastal Plain to determine the degree of habitat overlap between the two species. Dactylina arctica was present on all of 41 sampled pingos and occurred in a variety of microsites, although it was most common in shallow snowbanks and on north-facing slopes. Dactylina beringica occurred on 26 of 41 pingos and was limited to snowbank areas. Dactylina arctica and D. beringica have a significant negative association and occurred in the same plot only eight times. The local and microhabitat distributions of these species reflect their respective global distributions. Dactylina arctica is a ubiquitous, circumpolar species that is present in the High and Low Arctic, whereas D. beringica is an amphi-Beringian species occurring primarily in the Low Arctic. On pingos, D. arctica is more frequent and widespread than D. beringica and is also found in more extreme sites, with environments similar to those found in the High Arctic. The differential habitat preferences of these species demonstrated by these data is sufficiently great to warrant their recognition as separate species and not merely chemical morphs.

Microhabitat Preferences of Dactylina arctica and D. beringica on Pingos in Northern Alaska

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