Natural disturbance regime

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Ecology Theory (main)

May 5, 2009, 7:08 pm
October 20, 2011, 9:43 pm

Natural disturbance regime is a concept that describes the pattern of disturbances that shape an ecosystem over a long time scale. A natural disturbance regime is distinguished from a single disturbance event because it describes a spatial disturbance pattern, a frequency and intensity of disturbances, and a resulting ecological pattern over space and time. The specific natural disturbance regime is closely associated with the natural community in which it occurs.


Understanding ecological disturbance is necessary to understand the natural disturbance regime concept. According to Pickett and White, 1985, “a disturbance is any relatively discreet event in time that disrupts ecosystem, community or population structure and changes resources, substrate availability, or the physical environment.” Disturbances are events beyond individual growth and death of organisms in a community. Some examples of disturbances include: fire, wind, floods, disease epidemics, insect outbreaks, landslides, and avalanches. Humans can also cause disturbance (e.g., logging a forest), but these type of events are typically not considered part of a natural disturbance regime.

Causes of disturbance can be thought of as occurring along a continuum from endogenous (within the community) to exogenous (outside the community). Often disturbances are thought of as being exogenous, but the distinction is hard to make both because of the difficulty in separating direct and indirect effects, and because of the synergism between ecosystem condition and the probability of a disturbance. For example, in a forest endogenous insect pest activity can increase the chance of a high intensity wildfire that either originates within the ecosystem or spreads from outside.

Disturbances often create open space and make resources more available to biota in the ecosystem. They sometimes “restart” the process of succession by removing the current community and, in the case of a forest, opening up the space to more sunlight (Solar radiation). This allows shade-intolerant early-successional species to colonize the area. While disturbances are usually initially destructive of living organisms and/or organic material, they are important components of many ecosystems and can facilitate growth and renewal.

Natural Disturbance Regime concept

Natural disturbance regimes are characterized by the pattern and dynamics of disturbance events that mold the structure and species composition of an ecosystem. The natural disturbance regime concept includes disturbance distribution, frequency, rotation period, predictability, area disturbed, and magnitude intensity (or severity). Distribution is how the disturbances are spatially organized across a landscape. Frequency is the mean number of events per time period. Magnitude intensity is the physical force of the event. There is interplay between the conditions of an area and the natural disturbance regime and how they are influenced by each other over time. For example, a patchy canopy may be more susceptible to wind-throw disturbance than a completely closed canopy.

Disturbances do not always affect the entire landscape at the same time. Often, smaller patches experience disturbances at different times and intensities, creating a landscape-scale disturbance pattern. Concepts describing this pattern include: “patch dynamics” and “shifting mosaic steady-state.”

Use as a management concept

Understanding the natural disturbance regime of an ecosystem can help scientists and practitioners better understand and manage the factors that affect ecosystem structure and function. For example, silvicultural practices often try to simulate the natural disturbance regime of a particular [[forest] type]. Mimicking the historic natural disturbance regime such as fire and natural patterns of productivity in a landscape that has been altered by humans can help restore or conserve biodiversity, habitat for targeted species, productivity. This approach can also improve public opinion of management decisions. Examples of using a natural disturbance regime as a management tool for restoring ecosystems include controlled burns where fire suppression had previously been encouraged, small patch cuts where larger wind throws were part of forest development, and pasture rotation where grazing had previously been an important natural disturbance. In most cases in order to establish management plans it is useful to know what the “historic range of variability” of the ecosystem has been.


Use of the concept of a natural disturbance regime to inform management is complicated by human disturbance, large time scales that characterize the regime, sporadic return intervals, and changing management criteria over long time spans. Determining what “natural” means is also difficult. Does the natural disturbance regime include human influences on the landscape? Will human caused disturbance contribute to intensifying a natural disturbance regime over large time scales? Are management tools used by indigenous peoples part of a natural disturbance regime? Are management tools that mimic the understood natural disturbance regime considered part of the natural disturbance regime? If the reoccurrence of an earthquake is sporadic, can it be considered a disturbance regime – or is it an isolated disturbance? These are all questions that could benefit from further discussion and research, and hopefully enrich the natural disturbance regime concept.

Examples of disturbance

Further reading

  • Frelich, L. E. 2003. Forest Dynamics and Disturbance Regimes: studies from temperate evergreen forests. University Press, Cambridge.
  • Pickett, S.T.A., and P.S. White. 1985. The Ecology of Natural Disturbance and Patch Dynamics. Academic Press, Inc. Orlando, Florida.
  • Turner, M.G., R.H. Gardner, and R.V. O’Neil. 2001. In Theory and Practice: Pattern and Process. Springer-Verlag, New York.

Author notes

This article created as part of the Student Science Communication Project. Graduate student authors: Emily Stone and Lydia Menendez, Reviewer: Deane Wang. Class: Conservation Techniques and Approaches. See: EoE in the Classroom


Stone, E., & Menendez, L. (2011). Natural disturbance regime. Retrieved from