A Sensitivity Analysis of the Population Dynamics of Erythronium japonicum, a Liliaceous Perennial

Abstract

Abstract An individual‐based model for the population dynamics of a representative Japanese woodland herb, Erythronium japonicum, was constructed based on census data for eight years. The effects of intra‐specific competition were incorporated into the model. Several statistics on population dynamics, including intrinsic growth rate (r) carrying capacity (K), and steady‐state frequency distribution, were calculated by the model. Two kinds of sensitivities for intrinsic growth rate and carrying capacity were also obtained to examine the response of the population to the changes in several life history parameters. The changes in the relative growth rate (RGR) provided a higher sensitivity for intrinsic growth rate than the changes in mortality and in number of seedlings established. Incontrast, the changes in mortality gave a higher sensitivity for carrying capacity than for other vital rates. The sensitivity for sizeclass structure was also obtained: the size structure drastically changed in response to the changes in mortality in spite of the fact that changes in mortality showed a relatively low sensitivity to both intrinsic growth rate and carrying capacity. Several statistics on population dynamics obtained from a projection matrix model of E. japonicurn were compared to those from the individual‐based model. The population growth rate in the former model was smaller than that in the latter. The steady‐state frequency distribution in the former model was composed of more seedlings and fewer mature individuals than that in the latter model.