Phenotypic plasticity: A missing element in the theory of vegetation pattern formation

Climate change and the development of drier climates threaten ecosystems’ health and the services they provide to humans. Understanding the response of ecosystems to drier climates may provide clues on how to improve their resilience. Two robust mechanisms that improve ecosystem resilience are phenotypic changes in individual plants and partial mortality of plant populations to form vegetation patterns. In nature, these mechanisms are likely to act in concert, but their interplay has escaped consideration. We demonstrate the need for a theory that integrates these plant- and population-level mechanisms by addressing the fascinating fairy-circle phenomenon in Namibia. We show that such an integration resolves two outstanding puzzles in the current theory: observations of multi-scale patterns and the absence of theoretically predicted large-scale stripe and spot patterns along the rainfall gradient. Importantly, we find that multi-level responses to stress unveil a wide variety of more effective stress relaxation pathways, compared to single-level responses, implying a previously underestimated resilience of dryland ecosystems.