Joe Connell’s ideas and research have profoundly affected our perception of the roles of biotic interactions and abiotic factors in shaping the structure and dynamics of natural communities. His early investigations of rocky seashore communities in Scotland and Washington State were a seminal demonstration of how the interactions of interspecific competition, predation, and abiotic stress can determine the distributions of species along environmental gradients. Moreover, these studies demonstrated the power of field experimentation as a method for testing ecological hypotheses, and established field experiments as a mainstay technique of our discipline.
In the early 1960s, Connell shifted his focus from temperate rocky seashores to studies of mechanisms maintaining diversity in Australia’s Great Barrier Reef corals and Queensland rainforests, initiating some of the longest continuous studies of natural communities ever conducted (> 30 yrs). This also marked the beginning of his empirical studies of systems where physical disturbance played a large role in community dynamics. This work stimulated important conceptual contributions concerning mechanisms of succession following disturbance, the influence of disturbance on species diversity, and criteria for judging community stability. Connell and Slatyer (1977) formalized three alternative models that might drive species replacements following disturbance, and predicted how different characteristics of disturbance affect the rate and trajectory of successional response. This critical examination of the patterns and mechanisms of succession naturally led to the question of how different regimes of disturbance influence local species diversity. In his classic 1978 paper, Connell categorized and compared six alternative models for the maintenance of diversity. He concluded that the high species diversity of many tropical coral reefs and rainforests is largely attributable to regular disturbances that keep the assemblages in a non-equilibrium state, making competitive exclusion unlikely (Intermediate Disturbance Hypothesis). Subsequent analyses of the 38-yr sampling record of coral assemblages on Heron Island, Australia (Connell et al. 2004) provided strong support for this model, while also highlighting the interacting effects of habitat structure and local disturbance regime in generating spatial variation in diversity across the reef landscape.
Joe Connell’s incomparable long-term studies of community dynamics, his clear exposition of conceptual models of community response to variation in the biotic and abiotic environment, and his insistence on rigorous testing of alternative explanations for patterns in nature have inspired three generations of community ecologists. We salute him and gratefully thank him for sharing his ideas, principles, and great sense of humor.