Eco-geographical relations of the Bjørnøya vasular flora, Svalbard

Abstract

A renewed survey of the flora of Bjemeya (74" 31") has yielded a total of 54 native vascular species. Details of their distribution are provided by local maps and vertical frequency tabulations. Soil preferences of species and various plant communities are outlined. The general climate and microthermal conditions of the prevailing vegetation place Bjørnøya as a pronouncedly maritime part of the Svalbard archipelago, supporting mainly hygrophilous and chionophilous plant communitites and species. Only half of the island's vascular species persist at elevations above 200 m a.s.l., corresponding to a heat sum of July and August below approximately 190 Degree-Days. Ice-cored peat mounds coated by Rharomitrium lanuginosum were discovered on plateaux above 400 m elevation. The impact of the Vistula glaciation is discussed in view of Quaternary evidence from the Barents Sea area. Probably only one third of the present vascular flora could endure full-glacial conditions in possible ice-free cliffs on the coast of Bjørnøya.