From AMS Glossary
It has two main divisions: its northern portion is a belt of taiga or boreal woodland; its southern portion is a belt of true forest, mainly conifers but with some hardwoods. On its southern boundary the boreal forest passes into "mixed forest" or "parkland," prairie, or steppe, depending on the rainfall.
Hare, F. K. 1951. Compendium of Meteorology. 953, 957–958.