Arctic peatlands

Abstract

Arctic peatlands are mire ecosystems distributed across the vast northern edges of the Eurasian and North American continents and the islands and coastal areas of the Arctic and far northern Atlantic and Pacific Oceans. Arctic peatlands are mostly represented by "frozen" mires with much of their organic deposits remaining frozen throughout the year, whose water regime and other characteristics are strongly dependent on permafrost. Primary production in arctic peatlands is low, but the tendency for peat to accumulate is enhanced by the low decomposition rates. The peat layer in arctic peatlands is not thick, and only in rare cases does the peat exceed 4-6 m in depth. Three main permafrost processes are responsible for the variability of arctic frozen peatlands: thermokarst, frost heaving, and cracking. Arctic peatland diversity and distribution across the landscape depends on the climate conditions, permafrost presence, and hydrology-connected landscape dynamics, and adheres to a characteristic pattern which is beneficial to consider in inventory, mapping, or planning of wetland management. The ecosystem diversity of arctic peatlands is presented by paludified shallow peatlands; "frozen" peatland types such as polygon mires, peat plateaus, and palsa mires; and "nonfrozen" peatland types like patterned string fens, raised bogs, riparian mires, coastal tundra, and some types of coastal marsh. Arctic ecosystems are characterized by low species diversity, and typical species are highly specialized and intimately linked to their habitats. The short growing season limits annual production and the ecological niche capacity of these species. Arctic peatlands are highly integrated ecosystems which are extremely fragile to both natural and human-induced perturbations. With climate change, the arctic region will continue to warm more rapidly than the global mean. Peat, as a thermo-isolating material, plays a crucial role in minimizing permafrost thaw. However, climate change-induced peatland degradation introduces positive feedback with permafrost thaw. Accompanying rapid in situ peat decomposition is an increase in greenhouse gas (GHG) emissions, specifically methane from saturated peat water and that which was formerly bound in frozen permafrost. Development in such areas often ignores the special hydrological and ecological characteristics that are central to the productivity of these areas. Increased development of the oil and gas industry and its supporting transport infrastructure significantly fragments the landscape and disrupts its hydrology. Even traditional land uses such as reindeer herding are being industrialized. The resulting changes in peatland status will in turn restrict use of the land by the indigenous people who have traditionally depended on peatlands for food including herded reindeer, game, and fish. Thus, there is an urgent need to promote sustainable practices.