Further Observations on the Survival and Flowering of Some Perennial Herbs, I

The behaviour of individual plants of certain species has been studied on permanent quadrats laid out during the period 1942-1944 in forest and haymeadow in central Sweden. The results observed during the first four to six have been published in a preliminary paper (TAMM 1948). Of several interesting conclusions the most important concerned the rate of replacement of the species, both from seedlings and by branching. The rate of replacement, particularly from seedlings, has hitherto not received due attention. Earlier investigations, and particularly those conducted in Finland, have shown that in many plant communities only a very small percentage of the seedlings ever attain the floral stage (LINKOLA 1935; PERTTULA 1941). The true rate of reproduction is unknown, however, even in the meadow community which Linkola studied so closely. In Sweden, MALMSTR6M (1949) has pointed out the great difference in the rate and type of reproduction in forest communities for the mobile and equilibrium stages, but no figures are available for the rate of replacement in these various stages. In the preliminary paper figures were presented for the death rate and the rate of reproduction by vegetative propagation of certain species. It appears as if the conditions for the seedlings were even more adverse on the plots studies here than in the case of the types of vegetation studied by the Finnish investigators. The rate of renewal from seedlings was found to be almost nil in many cases, and the individual plants of the species studied must have been rather old. The figures presented were preliminary on account of the short period of observation and the difficulty of deciding the extent to which the communities under study were stable or developing towards a climax. Another observation of ecological interest concerned the rate of of certain species in different years. Annual differences in the number of individuals on the same plot were found not only for orchids (Orchis mascula and sambucina) but also for Primula veris and Sanicula europaea. It was concluded that flowering years occur for perennial herbs as well as for orchard