Meetings of the Botanical Society
Acta botanica neerlandica , Volume 17 - Issue 2 p. 160- 162
The palynological investigations, performed at the geological laboratory of the Catholic University of Nijmegen, chiefly confine themselves to the eastern middle Netherlands (the southeastern half of the province of Gelderland, northeastern Brabant and the northern part of Limburg). In this part of the country extensive peat regions do not occur. The peaty sediments present are found in abandoned (fossil) river beds, in small lakes, and in local depressions. The advantage of this is that the fossil pollen associations give a fairly accurate idea of the contemporary regional airborne pollen. The organic sedimentation in the region studied began locally in some abandoned river branches during the Bolling Interstadial. Betula was the most frequent tree. In addition to Betula nana, the first large birches will then have occurred (van der Hammen 1951.) In the vicinity of Nijmegen, the Pinus pollen was so numerous at that time, that it is doubtful if it arrived by long distance transport exclusively. Pollen of thermophile trees does not occur. The tree and non-tree pollen are in equilibrium (park landscape). In the Older Dryas time Betula dominates strongly within the tree pollen. It is possible, that the large birches disappeared and only Betula nana could maintain itself. The non-tree pollen dominates the tree pollen (park'tundra?). In view of the frequency of the pollen of Plantago, Helianthemum, Hippophaë and Artemisia, the vegetation must have had a steppe-like accent; so the climate had a continental character. The same conditions presented themselves in regions situated both more northerly and more southerly in the Netherlands.
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