Clonal Growth in Grassland Perennials: II. Growth Form and Fine-Scale Colonizing Ability

(1) The influence of growth form on the population dynamics of Bellis perennis and Prunella vulgaris was investigated in lawn communities by removal experiments. The rosette density of Bellis perennis was stable with time and little affected by the removal of either grasses or dicotyledonous species. In Prunella vulgaris, the module density changed greatly with time and was influenced by the presence of other dicotyledonous species in the sward. These differences are interpreted as typical of phalanx and guerrilla species. (2) Leaves were shorter-lived in Bellis perennis, where they shade each other more than in Prunella vulgaris. The longevity of leaves of both species is high during winter but low during the growing season. (3) The phalanx species Bellis perennis colonizes small bare patches mainly with seedlings, but the guerrilla species Prunella vulgaris colonizes mainly by clonal growth. Seedlings which attained adulthood were observed in Bellis perennis but not in Prunella vulgaris. (4) The contact-sampling method (Turkington & Harper 1979a, b) was used to analyse withinand between-species neighbour relationships. Its value is discussed and the suggestion is made to replace 'contact' by 'overlap'.