The impact of competition and litter accumulation on germination success in a model of annual plants

A new model of one type of annual plant dynamics is proposed and discussed. The model is based on individual agents Monte Carlo simulations. We take into account, the plant requirements for external resources (sunshine, moisture etc.), competition among plants and the influence of accumulated dead biomass on the plant germination and seed production. We show that the density of plants could have oscillatory character, with periods depending on the rate of biomass reduction. Investigations on the temporal changes in the spatial distribution of plants show some clustering and moreover persistence of patterns during the oscillations. The average number of seeds produced by a plant in a year versus density of plants has a power-law type character. The obtained results are compared with field data and findings in other theoretical models. Agreement with experimental data is found, at least on a qualitative level. We have been also able to add new arguments in the long debate about the existence or not of oscillations in plant dynamics.