An Integrated Model of Demography, Patch Dynamics and Seed Dispersal in a Woodland Herb, Primula vulgaris

Abstract

Primula vulgaris is a woodland herb often associated with canopy gaps. The canopy regeneration cycle results in a permanently changing environment which confers a dynamic character to the overall system of P. vulgaris populations inhabiting a forest. In order to describe the dynamics of this spatially structured population, we built a matrix model that incorporates both the spatio-temporal variation in its population dynamics and the dynamics of the forest habitat given by the opening and closure of canopy gaps. To build the model, we combined empirical data on 1) the demography of populations in various forest patches and 2) canopy closure rate. We then used the model to test the effect of disturbance rate and long-distance (i.e., off-patch) seed dispersal on overall population dynamics. Simulation results suggest that overall population growth rate of P. vulgaris would be enhanced by high gap opening rates, as this would increase the relative frequency of clearings, where population growth rate is maximal. Our analysis also predicts a negative effect of long- distance seed dispersal on overall population dynamics, since seeds dispersing out of occupied patches would have a high probability of landing in closed canopy patches. These results are an example of the costs of long-distance seed dispersal on overall population dynamics. Finally, the potential role of long-distance seed dispersal in the colonization of newly opened gaps is discussed.