Population dynamics of Plantago maritima along a distributional gradient on a Baltic seashore meadow

Abstract

Demographical studies of Plantago maritima along a 60 m long gradient, from waterfront to terrestrial meadow, revealed a correspondence in population dynamics. The gradient can be seen as a transition from dominance of density-independent mortality factors, mainly flooding, to a dominance of density-dependent mortality, mainly due to competition for light. In lower parts the variation in density of plants varies greatly between years, the flowering and seeding are good as well as the establishment of seedlings, i.e. there is a high turnover rate. In upper parts the flowering, seeding and establishment are poorer but the life expectancy is longer which results in a low turnover rate. The establishment of seedlings is mainly controlled by the access to light, in lower parts now and then dominated by the effects of flooding. Population characteristics change along the gradient so that reproductive effort, in terms of produced seeds per rosette, and allocation of biomass into reproductive organs is higher in lower parts but the reverse in upper, specimens in lower parts also start to grow and flower earlier.