Bioclimatical and Biogeographical digest of the Antarctic

Abstract

A first approach to Bioclimatology and Biogeography of the Antartic is carried out establishing the diagnostic parameters and indices of thermotypes, chionotypes (ombrotypes) and continentality existing in the study area following the Rivas-Martínez et al. (2011) proposal. It is also defined a new bioclimatic variant called Semipolar antarctic bioclimatic variant (sepoa). It has the optimal in the euhyperoceanic humid-ultrahyperhumid isles and archipielagoes of the subantarctic isles territories (Circumantarctic Subkingdom, Subantarctic Insular Region), located no far from the influence of the Antarctic Convergence, also afected by the West Wind Drift and the Circumpolar Cold Current, within 46º and 56º South latitude. To belong to the semipolar antarctic bioclimatic variant, every coastal island locality (<100m) must be in accord with the following six bioclimatic values: T 4.5º-7.5º (mean of annual temperature), Tp 380-860 (positive annual temperature), Tps 180-280 (positive summer temperature), Timax 5º-10º (mean temperature in warmest month), Ic 3.5-8.0 (continentality index), and Io 10-40 (ombrothermic index). Consequently with the bioclimatic values the potential natural vegetation and physiognomical communities (structure), at lower altitudes (<200 m), correspond with a treeless tundral communities; low thickets (<2 m), close grass-heaths, dwarf-heaths, wet or peat meadows, megaforbs, etc., in accord with the geomorphology and habitats. Biogeography up to the province level for Antarctica and adjacent territories is also proposed...