Influences of frost-heaving on vegetation and nutrient regime of polygon-patterned ground

Abstract

Actively frost-heaved polygon ground in an alpine area of nutrient-poor shrub heaths, had a large number of basophilous vascular plant species and cryptogams. The soils of the polygons had much higher concentrations of extractable plant nutrients and higher pH values than the surrounding stable ground, probably due to mixing of soils, intense weathering of the raw soil and lack of podzolization under conditions of high frost activity. Plant distribution was correlated to the intensity of frost-heaving; basophyte dominance was consistent with high pH and high extractable nutrient levels on the most actively upheaved polygon centres, whereas heath vegetation became increasingly dominant towards polygon borders with weaker activity, and on polygons with weak recent activity. Empetrum-heath species, usually distributed at sites with thin snow cover during winter, seemed better adapted to weak frost-heaving than species characteristic of communities normally developed in places with medium snow cover.