Post-Pleistocene Forest Migration as Indicated by Sediments from Three Deep Inland Lakes

Potzger, J; Wilson, Ira

Regardless of the defects and shortcomings of pollen analysis as an ecological method, the authors feel that it represents a much more accurate way of reconstructing successions of past vegetations than mere speculation about such phenomena in a given region. The chief sources of sediments used for analysis are peats from our numerous bogs north of the Illinoian glaciation limits. More recently pollen workers have also collected and examined sediments from existing lakes. While these may not disclose anything new on early succession of vegetation, they certainly present a complete spectrum up to the most recent times. Houdek (1935) pointed out that lake sediments could yield valuable records on vegetational developments in a given region, and described an instrument to make borings in such sediments. Last year Deevey (1939) presented data on pollen records from sediments of several lakes and ponds in Connecticut. All of the lakes investigated to date were shallow, and the manner of collecting samples from sediments leaves some doubt as to whether or not a complete profile was obtained, for the type of borers used limited collecting to sediments comparatively free of sand. This would at times eliminate many feet of sediments, especially in locations where sandy soils constitute the land along the shore. The present work shows that as many as twenty-three feet of sediments could, thus, be eliminated from the spectrum. Complete profiles are, however, highly essential if we hope to obtain a reasonably complete picture of the vegetational changes in a given region.

Post-Pleistocene Forest Migration as Indicated by Sediments from Three Deep Inland Lakes

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