Testing distributions on the shore
In Scottish intertidal research, Connell moved beyond describing the heights at which barnacles occurred. Removing, adding and transplanting barnacles and their predators allowed him to test biological explanations of distribution.
Competition and predation could thus be examined through altered field conditions. He continued community-ecology research at the University of California, Santa Barbara.
Permanent plots in reefs and forests
In the early 1960s Connell established long-term studies of Australian coral reefs and tropical rainforests. Permanent plots followed survival, recruitment and interactions rather than only comparing separate sites.
Records also covered disturbances such as fallen trees and cyclones, revealing change within communities that could otherwise appear stable.
References: [1]
Disturbance and competitive outcomes
Connell’s intermediate-disturbance hypothesis connected disturbance with coexistence. On reefs, cyclone waves could reduce dominant corals and permit recolonization by weaker competitors.
The explanation linked physical disturbance to competition. It remains a hypothesis to test in particular settings, rather than a prescription for an identical level of disturbance in every ecosystem.
References: [1]
Seedling survival and parent trees
The Janzen–Connell hypothesis concerns mortality associated with nearby conspecific adults and local conspecific density, potentially preventing a tree species from monopolizing space.
It directs attention to seedling survival near and farther from parents and to agents such as herbivores and pathogens. UCSB later established a field-ecology fellowship bearing Connell’s name.