What does the intermediate disturbance hypothesis predict about species richness?

The intermediate disturbance hypothesis suggests that the highest levels of species richness occur in environments where disturbances—such as physical events that clear habitat space—happen at intermediate levels of intensity and frequency.1

The hypothesis posits that when disturbances are rare, infrequent, or small in scale, resource availability is reduced, leading to a decline in the variety of species that can coexist. Conversely, when disturbances are too frequent or large-scale, they prevent the community from developing and evolving naturally, which also limits species diversity. Therefore, the hypothesis predicts that a moderate disturbance regime creates the optimal conditions for maximizing the number of species within a given area.1

It is important to note that some ecologists view this hypothesis as problematic, arguing that it can be difficult to define what constitutes a disturbance or to determine the appropriate scale for study. Furthermore, some researchers suggest that focusing solely on species richness may overlook other critical measures of ecological health, such as the relative abundance of species or the functional status of those affected by the disturbance.1