Simulation of secondary autogenic succession in the shortgrass prairie ecosystem

Abstract

Ecological succession is the process that dominates the dynamic behavior of ecosystems as they proceed from immaturity to a stage in which the living com munity achieves equilibrium with its physical envi ronment. Secondary succession refers to the tran sients that arise in response to a perturbation of a mature ecosystem. The growth-then-saturation dynamic pattern associated with this process is well known, but not well understood. The research reported in this paper formulates a dynamic model embodying a hypothesis to explain successional modes of behavior as they arise from the internal feedback structure of the ecosystem, and tests it by means of simulation experiments. The general structure of the model is based on Odum's tabular model of ecological succession; ¹⁶ it traces the mutual causalities between energy, living and non- living matter, and the diversity of species as they interact in time and space to produce succession. The equations are derived from grassland observations and research, biological theory, and logical neces sity. Simulation results are shown for secondary succession in a shortgrass prairie ecosystem. The simulated patterns exhibit consistency with the over all successional patterns observed in nature. Pro spective generalizations of the model to account for successional dynamics in grasslands and other eco systems are pointed out.