The occurrence and development of peat mounds on King George Island (Maritime Antarctic)

Abstract

On King George Island, South Shetlands Islands, a type of peat formation has been discovered which has not previously been reported from the Antarctic. These formations are in shape of mounds up to 7x 15 m in area, with a peat layer of about I m thick. About twenty five cm below the surface there is a layer of permanently frozen peat. The mounds are covered by living mosses (<em>Polytrichum alpinum</em> and <em>Drepanocladus uncinatus</em>), Antarctic hair grass (<em>Deschampsia antarctica</em>) and lichens. Erosion fissures occurring on the surface are evidence of contemporary drying and cessation of the mound's growth. The initial phase of the development of the mounds began with a community dominated by <em>Calliergidium austro-stramineum</em> and <em>Deschampsia antarctica</em>, and their further development has been due to peat accumulation formed almost entirely by <em>Calliergidium</em>. The location of the mounds is near a penguin rookery, which clearly conditioned the minerotrophic character of these formations, as compared with the "moss peat banks" formed by <em>Chorisodontium aciphyllum</em> and <em>Polytrichum al-pestre</em>. Moreover, the peat mounds differ from the latter in several ways, e.g. rate of growth and floristic composition. Radiocarbon dating of peat from the base of one mound gave an age of 4090±60 years B.P. This suggests that the age of the tundra on King George Island is about 5000-4000 years.