Spatial effects in an individual-based model of producer-herbivore interaction

In this paper, we describe an individual-based model of the interaction between a producer and herbivore species. The interaction occurs in a 2-dimensional matrix of individual cells. The producer organism grows in the cells and the herbiviores move between the cells, towards areas of high concentration of producer. Herbivores may die of starvation or they may reproduce asexually. The model is not built to represent a specific existing system but is a parsimonious generalized model of producer-herbivore interaction designed to test spatial effects. Although the model algorithm is kept simple--the herbivores have no learning or social behavior and have a minimal foraging strategy--the model displays some characteristics of real systems such as metapopulation behavior. We find significant effects on the herbivore and producer populations of the maximum move distance per step of the herbivores, the shape of the two-dimensional matrix, the quality of a corridor between patches habitable by the herbivores, and edge effects with fuzzy edges. The behavior of the model is comparable with empirical observations found in the literature, and we suggest that this simple model may be used to investigate the mechanism of these real effects.