A STAGE-STRUCTURED, STOCHASTIC POPULATION-MODEL FOR THE GIANT-KELP MACROCYSTIS-PYRIFERA

We have developed a population model for the giant kelp Macrocystis pyrifera (L.) C. Agardh in southern California, USA. The model includes five life-history stages and takes into account environmental and demographic stochasticity, as well as density-dependent interactions. The density of each stage is predicted on a monthly basis for up to 20 yr, and extinction probability is determined for adult sporophytes. Survival probabilities and rates of reproduction and growth are based on stage-specific responses to environmental conditions (irradiance and temperature), including the occurrence of El Niño events. The model is validated by comparing simulation results to empirical data from natural kelp populations. Results of the model provide insight into patterns observed in natural populations and have applications in resource management. © 1990 Springer-Verlag.