KEY FINDING 19. The dynamics of natural disturbance regimes, such as fire and native insect outbreaks, are changing and this is reshaping the landscape. The direction and degree of change vary.
Natural disturbances are discrete, sometimes cyclical, events that cause significant change in ecosystem structure or composition. Size, frequency, severity, seasonality, and duration of the disturbance event determine the impact on biodiversity. Large disturbance regimes are important as they have shaped ecosystems. Although other disturbance agents are important, this key finding focuses on fire and native insect outbreaks which are widespread and particularly important ecological drivers in forests and grasslands. Fire and insect outbreaks affect each other and are influenced by weather, climate, vegetation dynamics, and human management.