Paradigm Integration between Equilibrium and Non-equilibrium Concepts for Evaluating Vegetation Dynamics in Rangeland Ecosystems

摘要

There are two major paradigms involved in applied ecological research on rangeland ecosystems: the equilibrium paradigm and non-equilibrium paradigm. The former idea posits that communities will respond in a sequential and predictable manner to the environment and disturbances such as grazing. The latter idea has minimized ecosystem regulation and stability and placed greater emphasis on external factors such as climatic variability and episodic events, implying that ecosystems are less predictable than indicated by the equilibrium concept. Previous literature has suggested that both equilibrium and non-equilibrium paradigms must be incorporated into rangeland management perspectives if the solid science of rangeland ecology is to continue to underpin them. However, the current state-of-the-art in rangeland management appears to be progressing at the extremes of the equilibrium-non-equilibrium continuum. Consequently, there is uncertainty as to whether the current knowledge is the key to successful environmental management of rangeland ecosystems. Here, I have synthesized the extensive debates on rangeland ecology from a rangeland management perspective, and merged the two major paradigms by placing the idea of ecological thresholds at the core of the study framework. The clear implication is that both equilibrium and non-equilibrium paradigms must be incorporated into vegetation management in rangeland ecosystems. Effective vegetation management based on both paradigms can prevent adverse changes in states before ecological thresholds are reached, while maintaining or enhancing the ecological resilience of rangeland ecosystems.