Responsiveness and resilience of high Arctic ecosystems to environmental change

Although polar semi-desert and polar desert ecosystems are extensive in the high Arctic (covering around 1.98 x 106 km2) they have been the subject of relatively few studies of structure, function and temporal dynamics in relation to environmental change. The mosaic of incomplete vegetation cover and much bare ground, which distinguishes polar desert and semi-desert ecosystems from the more 'closed' tundras of the low- and sub-Arctic, may predispose high arctic ecosystems to responsiveness to environmental change by providing opportunities for lateral spread of existing vegetation and immigration of plant species from further south. There are also, however, several factors that are likely to confer resilience (or 'inertia') to change in the high Arctic: these include (i) poor soil nutrient and/or moisture status, which exert a strong control both on clonal and sexual proliferation of plants, (ii) the presence of genetic polymorphisms within existing plant populations which have the potential to 'buffer' high arctic vegetation from the impacts of change, and (iii) severe physical barriers to long-distance dispersal of diaspores. Our aim in this paper is therefore to synthesize existing information to assess the potential responsiveness and resilience of high arctic ecosystems to environmental change. We draw on results from environmental manipulation experiments, eco-physiological and plant demographic studies, and a consideration of palaeoecological and pedogenic processes in the high Arctic.