Disturbances occur in all ecosystems, but there is no general theoretical framework that encompasses the various aspects of disturbance and their individual and interacting effects on biological communities. The frequency, intensity, duration, extent, and timing of disturbance can each influence the ability of species to coexist and the ability of new species to invade existing communities. Interactions among these aspects of disturbance further complicate their impacts, creating a need for a robust theoretical framework that can be applied to many ecosystems and to individuals, populations, and communities. An ecological niche-based theory of disturbance will be developed using analytical and simulation models, linking species traits to disturbance regimes and population dynamics. If successful, the project will create a common framework for a diverse literature on disturbance, significantly advancing our understanding of disturbance as a driver of biological diversity. The utility of the resulting models will be tested by applying them to three case studies: invasion and management of non-native thistles, fire and grazing disturbance interactions in Australia, and coexistence of species in deep-sea hydrothermal vent systems. Broader impacts of this project are present because human activities are changing disturbance regimes in virtually all ecosystems, with unknown consequences for species coexistence and diversity, and because disturbance has played a key role in the spread of many invasive species. A comprehensive theory of disturbance will inform scientists and natural resource managers when and where changes in disturbance are likely to pose threats to diversity or change the susceptibility of an ecosystem to invasive species.