What is the intermediate disturbance hypothesis in simple terms?

If disturbances like fires or storms are too frequent, only tough species survive; if too rare, strong competitors take over. At moderate levels many species live together, so diversity is highest.

Is the hypothesis still accepted?

It is widely taught as a classic theory, but empirical studies do not consistently find the hump-shaped pattern and there are theoretical criticisms, so whether to abandon it is debated.

Intermediate Disturbance Hypothesis

🔬 Natural Sciences By CampusDown Wiki Editorial Team Last updated October 26, 2026 Views 5

The intermediate disturbance hypothesis is an ecological hypothesis holding that species diversity in a community is highest at intermediate frequencies or intensities of disturbance such as fire, storms, floods or waves, because frequent or severe disturbance leaves only a few tolerant species, while rare or weak disturbance lets strong competitors exclude others. Joseph Connell formalized it in 1978.

Contents

1. Origins and basic logic
2. Experimental tests and theoretical extensions
3. Evidence and the debate over abandonment
4. FAQ
5. References

Origins and basic logic

Hutchinson (1961) argued that if the environment changes before reaching equilibrium, competitive exclusion is never completed and many species can coexist. Grime (1973) proposed a hump-shaped relationship in grasslands, where intermediate stress such as mowing or grazing suppresses dominant species and raises diversity, and Horn (1975) treated forest succession with probabilistic models. Explaining why tropical rainforests and coral reefs are so diverse, Joseph Connell (1978) drew these ideas together as the intermediate disturbance hypothesis. Right after a disturbance only fast-colonizing pioneer species arrive, and after long periods without disturbance strong late-successional competitors dominate through competitive exclusion; at intermediate levels pioneers and late species mix, so diversity peaks.

Experimental tests and theoretical extensions

Sousa (1979) studied boulders of different sizes in the California intertidal zone that waves overturn at different rates. Small, frequently overturned boulders held only pioneer green algae, large boulders that rarely moved were dominated by competitively superior red algae, and intermediate boulders held the most species. Huston (1979) proposed a dynamic equilibrium model in which disturbance frequency and population growth rates jointly determine diversity, and Pickett and White (1985) established disturbance and patch dynamics as central topics in ecology. Petraitis, Latham and Niesenbaum (1989) systematized the mechanisms by which disturbance maintains diversity, and Roxburgh, Shea and Wilson (2004) and Shea, Roxburgh and Rauschert (2004) modeled the conditions under which hump-shaped patterns reflect genuine coexistence mechanisms.

Evidence and the debate over abandonment

Reviewing more than 100 studies, Mackey and Currie (2001) reported that hump-shaped disturbance–diversity relationships appear only in a minority of cases, with monotonic increases, decreases or no relationship also common. Fox (2013) argued that the hypothesis should be abandoned, because the logic that disturbance interrupts competition and thereby promotes coexistence is theoretically flawed and the empirical support is weak. Sheil and Burslem (2013) countered that Connell's original hypothesis concerned the interaction of disturbance and succession and remains useful in tropical forests and elsewhere. The debate has led to the understanding that disturbance affects diversity not through a single pattern but in ways that vary with ecosystem, scale and type of disturbance. The hypothesis is treated as a classic theory of community diversity alongside keystone species and island biogeography.

FAQ

What is the intermediate disturbance hypothesis in simple terms?: If disturbances like fires or storms are too frequent, only tough species survive; if too rare, strong competitors take over. At moderate levels many species live together, so diversity is highest.
Is the hypothesis still accepted?: It is widely taught as a classic theory, but empirical studies do not consistently find the hump-shaped pattern and there are theoretical criticisms, so whether to abandon it is debated.

Sources reviewed: 2026-10-26

References

Connell, J. H. (1978). Diversity in tropical rain forests and coral reefs. Science, 199(4335), 1302–1310.
Grime, J. P. (1973). Competitive exclusion in herbaceous vegetation. Nature, 242(5396), 344–347.
Horn, H. S. (1975). Markovian properties of forest succession. In M. L. Cody & J. M. Diamond (Eds.), Ecology and Evolution of Communities (pp. 196–211). Cambridge, MA: Harvard University Press.
Hutchinson, G. E. (1961). The paradox of the plankton. American Naturalist, 95(882), 137–145.
Sousa, W. P. (1979). Disturbance in marine intertidal boulder fields: The nonequilibrium maintenance of species diversity. Ecology, 60(6), 1225–1239.
Huston, M. (1979). A general hypothesis of species diversity. American Naturalist, 113(1), 81–101.
Pickett, S. T. A., & White, P. S. (Eds.). (1985). The Ecology of Natural Disturbance and Patch Dynamics. Orlando: Academic Press.
Petraitis, P. S., Latham, R. E., & Niesenbaum, R. A. (1989). The maintenance of species diversity by disturbance. Quarterly Review of Biology, 64(4), 393–418.
Roxburgh, S. H., Shea, K., & Wilson, J. B. (2004). The intermediate disturbance hypothesis: Patch dynamics and mechanisms of species coexistence. Ecology, 85(2), 359–371.
Mackey, R. L., & Currie, D. J. (2001). The diversity–disturbance relationship: Is it generally strong and peaked? Ecology, 82(12), 3479–3492.
Shea, K., Roxburgh, S. H., & Rauschert, E. S. J. (2004). Moving from pattern to process: Coexistence mechanisms under intermediate disturbance regimes. Ecology Letters, 7(6), 491–508.
Fox, J. W. (2013). The intermediate disturbance hypothesis should be abandoned. Trends in Ecology & Evolution, 28(2), 86–92.
Sheil, D., & Burslem, D. F. R. P. (2013). Defining and defending Connell's intermediate disturbance hypothesis: A response to Fox. Trends in Ecology & Evolution, 28(10), 571–572.

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Competitive Exclusion PrincipleWhat the competitive exclusion principle is: why two species using the same limiting resource in the same way cannot stably coexist, Gause's experiments, Lotka–Volterra models, niches, the paradox of the plankton and coexistence theory.🔬 Natural Sciences Keystone SpeciesWhat a keystone species is: a species with an effect on ecosystem structure disproportionate to its abundance, its origins in Paine's intertidal experiments, sea otters, trophic cascades, ecosystem engineers and critiques.🔬 Natural Sciences Island BiogeographyWhat the theory of island biogeography is: species richness set by a balance of immigration and extinction, more species on larger and nearer islands, species–area curves, the mangrove experiments and conservation uses.🔬 Natural Sciences MetapopulationWhat a metapopulation is: a population of local populations linked by dispersal, its origins, the Levins model and equilibrium occupancy, Hanski's incidence function model, fragmentation, extinction debt and metacommunities.🔬 Natural Sciences Allee EffectWhat the Allee effect is: why individual fitness or population growth falls at low density, its origins in Allee's work, component vs demographic effects, strong effects and critical density, mechanisms, and uses in conservation, fisheries and invasions.🔬 Natural Sciences

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This article was last updated on October 26, 2026. It is based on widely recognized original works and textbooks; when citing it in a paper, please check the original sources listed in the references.