Landschaftsökologische Gliederung des westlichen James Bay-Tieflandes (Nord-Ontario) im Bereich der polaren Waldgrenze

Abstract

This paper deals with the ecological landscape pattern in the southwestern James Bay Wetlands (Northern Ontario) and the problem of the climatological position of the Forest-Tundra-Transition-Zone north of the Boreal Forest. Since up to 52° N all isolated locations with mineral soils are occupied by closed forests of black or white spruce, aspen or jackpine, this part of the wetlands must climatologically be considered an extension of the Boreal Forest Climatic Region. The regional pattern of different wetland landscapes is explained with the enclosed map (Supplement V), based on the interpretation of LANDSAT images and a great number of ground checks. The central part of the wetlands is the Moose-River Basin. It is surrounded by bedrock uplands with boreal forests in the south and west and by interfluvial till plateaus in the northwest and southeast. Satellite images characterize the latter by numerous small pools and lakes. The subsoil consists of basal till deposits. The peat depth increases with the distance from the coast from 1.0 m to 3.0 m. In the lower plateau areas fens occupy approximately 72 % of the unit, in the upper plateau areas large treed and shrub-rich bogs are the dominant types (approx. 65% coverage). The subsoil of the Moose Basin consists of marine sediments. The dominant physiographic units are the levees along the abandoned and present drainage channels of the main rivers, the young tamarack fens, the tamarack + black spruce fens with shrub undergrowth (muskegs sensu stricto), the muskegs with extended treed bogs, and the bog + fen-border to the interfluvial plateaus.