The vegetation of the Canadian Prairie Provinces 1. An overview
The Canadian Prairie Provinces form the transition from the North American Great Plains to the Boreal forests. Of the total extent of 2,000,000 km2 about 600,000 km2 is in the inhabited area; the remainder is very thinly populated. Cultivated crops and hayland occupy 350,000 km2, and native vegetation in the inhabited part occupies about 235,000 km2, and native vegetation in the inhabited part occupies about 235,000 km2. Most of the native vegetation is prairie. The climate of the Prairie Provinces is continental; about 60 % of the precipitation falls during the growing season. Variations in precipitation and temperature have been used to map climatic zones, which can be correlated with vegetation types. Soils are mostly derived from glacial deposits, but large areas of sand dunes and saline soils can be found. Soil types described in the area are associated with the various vegetation types. Three major vegetation types can be distinguished: the grasslands, shrub-communities, and coniferous forests. Previous classifications or descriptions of these vegetation types are reviewed, and its affinities to Eurasian communities discussed. The possibility of uniting most vegetation types into Class-groups is shown with the example of the prairies. The inter-relationships of the vegetation-types, and possible succession series are discussed. It is pointed out that the elimination of the bison and man-made fires, have resulted in the encroachment of woody vegetation on grassland in several parts of the Prairie Provinces.