Disturbance, productivity, and species diversity: empiricism vs. logic in ecological theory.

The "intermediate disturbance hypothesis" and the "intermediate productivity hypothesis" have been widely recognized concepts for explaining patterns of species diversity for the past 40 years. While these hypotheses have generated numerous reviews and metaanalyses, as well as persistent criticism, two prominent papers have recently concluded that both of these hypotheses should be abandoned because of theoretical weaknesses and failure to predict observed diversity patterns. I review these criticisms in the context of the continuing tension between logic and empiricism in the development of ecological theory, and conclude that most of the criticisms are misguided because they fail to recognize the inherent connections between these two hypotheses, and consequently fail to test them appropriately. The logic of every hypothesis is based on the underlying assumptions. In the case of these two hypotheses, the assumptions on which the criticisms of their logic depend are falsified by the strong empirical support for the linked predictions of the hypotheses. This conclusion calls for a réévaluation of the basic assumptions upon which most of ecological competition and diversity theory is based. [ABSTRACT FROM AUTHOR]