A Study of Two Forest Stands in Minnesota with an Interpretation of the Prairie‐Forest Margin

Abstract

The deciduous forest extends northwestward in the northern half of Minnesota as a narrowing band between the coniferous forests on the east and the prairies on the west. This is well illustrated by Upham's original map of the vegetation of Minnesota and the various reproductions of it (Upham 1884, Rosendahl and Butters 1928, Daubenmire 1936, Buell and \Wilbur 1948). As is characteristic of such major vegetational transitions, the contacts of the deciduous belt with adjacent formations are usually not sharp. There is evidence that they are not at present in a state of equilibrium. As Griggs (1946) infers, such contacts probably seldom are. East of the hardwood belt there is a broad transition zone between it and the coniferous forests where, in the pattern of distribution of the vegetation, the conifers form the continuous phase and the maple-basswood community the discontinuous l)llase. Continuing eastward in northern Minnesota there are increasingly greater distances between the stands of the hardwood forest. West of the hardwood belt the continuous phase gradually shifts from deciduous forest to prairie. Isolated stands of trees or clumps of shrubs occur along the easternmost margin of the prairie. The transition to prairie is sharper than that to