Summary
Predicts diversity is highest at moderate levels of disturbance.
In depth
Frequent disturbance eliminates sensitive species; rare disturbance lets competitive dominants exclude others; intermediate levels allow coexistence. Support is mixed.
At low disturbance, competitive dominants win; at high disturbance, only tolerant species survive. Tested in tropical forests, intertidal and coral systems with mixed results.
Remember: the hypothesis predicts a hump-shaped curve of diversity.
Joseph Connell proposed it in 1978 from studies of tropical rainforests and coral reefs. At low disturbance, competitive dominants take over; at high disturbance, only fast colonisers survive; and at intermediate levels there is a mosaic of patches at different stages, supporting colonisers and competitors. Evidence includes intertidal boulders turned over by waves, where mid-sized patches have most species.
The hypothesis has been criticised: reviews find that the humped pattern is not universal, and it depends on how disturbance and diversity are defined. It remains influential in management, for example for controlled burns and grazing to maintain diversity in grasslands.
Key idea: disturbance is a natural process, and some is needed to keep diversity high.
Frequently asked questions
What is Intermediate Disturbance Hypothesis?
Predicts diversity is highest at moderate levels of disturbance.
Which area of biology covers Intermediate Disturbance Hypothesis, and how advanced is it?
Intermediate Disturbance Hypothesis is one of the 54 topics in Ecology. It is rated Advanced, so it suits learners who want specialist depth. Related topics in this area include Allee Effect, Ecology, Biomes.
Can you give an example of Intermediate Disturbance Hypothesis?
Coral reefs with moderate storm damage often have highest diversity.
What should I learn before Intermediate Disturbance Hypothesis?
Work through the Beginner topics in Ecology first, such as Ecology, Ecosystem, Biotic and Abiotic Factors, then return to Intermediate Disturbance Hypothesis. Advanced topics assume the Intermediate vocabulary.
What topics are related to Intermediate Disturbance Hypothesis?
The closest topics to Intermediate Disturbance Hypothesis are Allee Effect, Ecology, Biomes, Competitive Exclusion. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Intermediate Disturbance Hypothesis?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Intermediate Disturbance Hypothesis. To practise the whole of Ecology, use the Ecology quiz.
How is Intermediate Disturbance Hypothesis different from Allee Effect?
Intermediate Disturbance Hypothesis: Predicts diversity is highest at moderate levels of disturbance. Allee Effect: At low density, individual fitness declines, so small populations may fail to recover. Read both side by side and note what each one explains.
How should I study Intermediate Disturbance Hypothesis step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Allee Effect and explain the difference aloud. Finally, take the Ecology quiz and come back to this page for any question you miss.