Disturbance Dynamics and Ecological Response: The Contribution of Long-Term Ecological Research

T he important role of disturbances in shaping land- scapes and influencing ecosystems is now well recognized in ecology. Fires, storms, floods, pest outbreaks, species invasions, and resource extraction, to name but a few types of disturbance, affect many ecosystems over a range of spatial and temporal scales. Disturbance is defined as "any relatively discrete event in time that disrupts ecosystem, community, or population structure and changes resource pools, substrate availability, or the physical environment" (White and Pickett 1985); it may be natural or anthropogenic in origin. This general but flexible definition requires that the spatial and temporal scales of the system and disturbance be specified. Disturbances span a broad range of sizes and frequencies and can be characterized by their extent, spatial distribution, frequency or return interval, predictability, and magnitude, including both intensity and severity