[2] Connell's first research paper examined the effects of interspecific competition and predation on populations of a barnacle species on the rocky shores of Scotland.
[2] Together, with a subsequent barnacle study on the influence of competition and desiccation,[4] these two influential papers have laid the foundation for future research and the findings continue to have relevance to current ecology.
[8] Among his important works were the Connell–Slatyer model of ecological succession (facilitation, tolerance and inhibition) and the Janzen-Connell hypothesis that explains plant-species diversity in tropical forests.
[17] Much of his studies focused on determining community structure based on physical factors, actions and interaction of species that are involved in competition, predation, and recruitment.
[18] Connell’s paper on “Diversity in tropical rain forests and coral reefs” made it clear that disturbance has crucial impacts on ecological communities.
He explored that trees in the tropical rain forest and coral reefs are in non-equilibrium state, and if they are not disturbed, then they will progress towards low-diversity equilibrium community.