ON THE ECOLOGY OF SHORT-LIVED FORBS IN CHALK GRASSLANDS: LIFE-HISTORY CHARACTERISTICS

Authors


Summary

The life-histories of Carlina vulgaris L., Daucus carota L., Euphrasia officinalis L., Gentianella germanica (Willd). Börner, Linum catharticum L., and Scabiosa columbaria L. in a chalk grassland in the Netherlands are described on the basis of frequent observations during a period of three and a half years.

E. officinalis and a small part of the L. catharticum population were found to be annual. G. germanica and the major part of the L. catharticum population were biennial, whereas the other species took several years to reach maturity. All species except the major part of the Scabiosa columbaria population were monocarpic.

Vegetation cover influenced the occurrence of short-lived forbs, but a large variation is found in the data. In D. carota, E. officinalis and Scabiosa columbaria seed production had a marked effect on seedling density in the following year.

Shoot growth in Scabiosa columbaria seedlings varied at various vegetation densities. Furthermore, a marked correlation was found between rosette size and the probability of becoming mature in the subsequent year.

Within one grassland, life-history types within the group of short-lived species are found to vary. On the one hand, there are the small-seeded annuals with high mortality, but rather constant density of mature plants (Euphrasia), and on the other hand there are the more conservative life histories (Carlina, Daucus and Scabiosa), with larger seeds, lower mortality rates, but higher age of first reproduction and considerable variation in the density' of individuals.

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