MIGRATION AND COLONIZATION BY VASCULAR PLANTS IN A NEW POLDER

The migration and subsequent colonization in three habitats of the recently reclaimed Lauwerszeepolder, the Netherlands, is described. Origin of propagules, accessibility and other environmental features determining the success of ecesis, are briefly discussed. Dispersal spectra and life form spectra of the flora of three habitats in the first, second and sixth years are compared.Regarding migration, the data can be summarized as follows:- Eu-hydatochorous dispersal played a dominant role in all habitats deseribed. - Probably the seed populations of many species were present at the time of the enclosure. - After six years anemochorous species dominated on the musselbanks and the desalinated sandflats, not only because of their increase, but also because many hydatochorous species disappeared. - The dispersal spectra of the remarkably different habitats M and Z showed a great resemblance after six years. - On the musselbanks, the largest number of species was found in the second year. - A still larger number of species was found on the desalinated sands after six years.The colonization and the first successional trends can be summarized as follows:- In the first year, therophytes dominated. - A marked shift from therophytes towards hemicryptophytes was found in all habitats. Only a small number of species belonged to other life forms. - The life form spectra of the remarkably different habitats M and Z showed a great resemblance after six years. © 1978 Dr. W. Junk Publishers.