The boreal zone and its biotic subdivision

Abstract

A preliminary map of the latitudinal, transcontinental subzones of the Eurasian and North American circumboreal vegetation zone is presented. The recognized subzones are called herniboreal, southern boreal, middle boreal and northern boreal. Along the humidity ‑ aridity gradient the zone may be divided into several sectors (not mapped). The highly humid sectors may be characterized by treeless heaths, and birch and/or alder woods or ‘krummholz’ thickets, while moderately humid sectors are pri­marily dominated by coniferous forests. In the arid sectors there are areas of aspen and larch woods and even boreal steppe vegetation.