Soils of Alaska: LRRs W1, W2, X1, X2, and Y

Abstract

Alaska covers 1,508,120 km², about 25 % of the contiguous USA. Alaska is organized into three Land Resource Regions (LRRs): Southern and Aleutian Alaska (W1, W2), Interior and Western Alaska (X1, X2), and Northern Alaska (Y). The soil moisture regimes range from subhumid and humid in northern, interior, and western Alaska to humid and perhumid in southern Alaska. The soil temperature regime ranges from cryic in southern Alaska to pergelic in northern Alaska. Northern Alaska has continuous permafrost, and thus, the soils are dominantly Gelisols formed under tundra with gelic Inceptisols and Entisols in areas shallow to bedrock and along streams. Very small areas of gelic Mollisols are found on well-drained uplands with calcareous parent materials. Interior and Western Alaska are in the zone of discontinuous permafrost . Gelisols dominate northerly slopes under black spruce forest and peatlands. Inceptisols dominate southerly slopes and well-drained uplands under white spruce and deciduous forests. Histels or Histic Gelisols dominate poorly drained lowlands and depressions. In southern and western Alaska, moderately leached Spodosols form in volcanic ash and glacial deposits under conifer forests, and Andisols form under herbaceous and grassy vegetation. Histosols form in extensive peatlands in southern Alaska. There are limited areas in Interior and Southern Alaska under cultivation for grains, hay, and vegetables. Urban use of land is limited because of small population in the state. Most lands are in native forest and rangelands supporting wildlife habitat.