Floristisch onderzoek naar Van Soests plantengeografische districten van Nederland
Gorteria Dutch Botanical Archives , Volume 9 - Issue 5 p. 142- 154
In 1932 VAN SOEST finished his series of papers, started in 1924, about the subdivision of the Netherlands into phytogeographical districts. From that moment on generations of Dutch floristic and other botanical fieldworkers were confronted with the picture of this subdivision, reproduced in every new edition of the Netherlands floras. As a historical survey of the evolution of Van Soest’s ideas about the phytogeographical districts of the Netherlands has never been composed, these anniversary papers seem to be in the view of the present author a good opportunity to do so. Unescapably this survey leads to some critical remarks, that, curiously enough have never been heard in the period of more than 45 years of existance of this subdivison. The author proposes the recognition of an independant freshwater-tidal-district. Recent floristic researches, especially those in the borderarea of two districts, have given a lot of information about the character of this borderland, which evidently can not be characterised as uniform. The border between the Dune and the Hafdistrict has always been found to be rather sharp; other borders, e.g. those between the Fluviatile and the Flamish, the Haf or the Kempens district are usually rather vague. The border between the Dune and the Waddendistrict is also less sharp. Attempts are made to characterize the various districts by a minimum total number of species, and a minimal floristic value of certain sociological-ecological groups as distinguished by VAN DER MAAREL (1971). Finally the author warns against hasty radical changes in the so well-known subdivision into phytogeographical districts of the Netherlands, as published by Van Soest more than 45 years ago.
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