Plant Characteristics Over a Century of Primary Sucession on Islands: Lake Hjalmaren

Publisher Website
Google Scholar
Abstract
Between 1882 and 1886 the water level of Lake Hjalmaren, Sweden was lowered °130 cm. As a consequence, a large number of new islands arose. From 30 such islands we have complete lists of vascular plant species with notes on their abundance from 1886, 1892, 1903—1904, 1927—1928, and 1984—1985. The 112 most important species were grouped as pioneers, early—, mid—, or late—successional, depending on when in the sere they were most abundant or frequent. Several species (referred to as stayers) remained common once they had entered the succession. For the 112 species we collected literature data on height, life form, fecundity, mating system, pollination, seed size, dispersal, and relation to nitrogen and light, and the successional groups were compared with regard to these attributes. The characteristics of the pioneers were distinct from other groups. Eight of the 13 pioneers were annuals (therophytes), all of which were predominantly autogamous, indicating a strong coupling between these life history traits. After the pioneer stage there was no continuous change in these attributes. The seeds in pioneers were not smaller than in early— or midsuccessional species, and seed size did not differ between annuals and perennials. Water dispersal was very important, and therefore dispersal success put no constraint on seed size. Species with the heaviest seeds arrived late; notably they were bird dispersed. Only among wind—dispersed trees and shrubs was there a gradual increase in seed mass over succession. The Ellenberg light indicator value showed a slight decrease over time, as did a variable measuring preference for open habitats. We propose that physiology may be more important than life history for species replacements after the pioneer stage.

This publication has 0 references indexed in Scilit: