The neglected role of limiting factors in large-scale abundance patterns

The Law of the Minimum states that species’ abundance at a location is limited by one single factor. If true, abundance-environment plots should take polygonal shapes constrained by an upper boundary representing the maximum abundance that the species can reach across the environmental gradient. Here, we examine the generality of polygonal plots in the literature and in observational data, and assess how often they are analyzed under the theory of ecological limitation. We also present a proof-of-concept of a method to identify polygon-shaped plots. We found polygonal plots in 76% of reviewed studies and in 73% of the 300 analyzed tree and bird species. We demonstrate that polygonal shapes with upper boundaries are prevalent in abundance-environment plots; yet they are rarely interpreted considering the Law of the Minimum. A wider acknowledgement of limiting relationships would improve our ecological understanding and estimation with further benefits to theoretical and applied ecology.