The value of stress and limitation in an imperfect world: A reply to Körner

A recent perspective paper offered by Körner essentially argued that 'limitation' and 'stress' are functionally useless terms for ecology except perhaps within limited contexts such as plant physiology or agriculture. We strongly disagree, and to this end argue that, although stress is not as precise as other concepts in ecology and is probably more difficult to apply to communities than to individuals, if ecologists want to communicate in a meaningful and interesting way about the distribution and abundance of species, we have to use multi-purpose terminology that allows us to scale from reductionistic, strictly quantifiable levels of analysis to more general conceptual levels. Here, we revisit the main arguments presented against these concepts and use three lines of counter-argument to support our conclusion that limitation and stress are necessary concepts for organizing and integrating general ecological inquiry. We discuss (1) the role of interactions between individuals in changing the limitation experienced by a species, (2) the importance of delineating whether stress is being applied to individuals or to the community, and (3) the evolutionary argument that fitness is never perfect since even adapted species are likely limited to some degree by the environment.