A comparison between the recent regional pollen rain and the sub-recent vegetation in four major vegetation types in minnesota (U.S.A.)

In four regions in Minnesota, covered by different types of vegetation, the regional pollen frequencies of a number of tree types and the composition of the regional forest type have been determined. It is concluded that: 1. (1) The forest types are recognizable from the pollen percentages. 2. (2) The ratio pollen percentage/vegetation percentage, the degree of representation of a pollen type, is different from one region to another. 3. (3) In regions with the same sort of topography the ratios vary within certain limits to such an extent that application of correction factors for a few pollen groups remains possible. 4. (4) The ratios are lowest when a tree species is frequent in the regional forest and highest when it is not very abundant