Population dynamics of a perennial herb (Plantago maritima L.) along a distributional gradient : a demographical study

Abstract: In order to explain density distribution and provide the basis for further research on life history phenomena, the demography of Plantago maritima is described along a distributional gradient from mean water level to the epilitoral. The results seem to suggest that the factors affecting distribution are differences in 1. non age specific mortality due to submergence, 2. flowering frequency and reproductive effort, 3. the fate of flowers and seedling success, 4. the efficiency of seeds producing seedlings and 5. the number of successful establishments. Experiments to identify the causes of flowering differences were performed and it became clear that the competition for light in upper parts is of great importance. In the lower parts the addition of nutrients increases flowering significantly. In addition the effects of selective grazing by cattle on reproduction vary along the gradient. The plants adjust to the environment and show differences in life history phenomena along the distributional gradient.The study is published in five parts.