After investigating alternative explanations and finding them unsatisfactory, Professor Ehud Meron and his team believe that the combination of spatial patterns and phenotypic variation provides the answer.

Fairy circles, characterized by nearly hexagonal circular, bare earth spaces between grasslands, were first discovered in Namibia and later in various parts of the world. These interesting formations have fascinated and surprised scientists for a long time.

Hypotheses regarding their origin include a range of theories, from the concept of spatial self-organization due to the interaction between water availability and vegetation dynamics to the possibility of influencing these patterns through the basal distribution of termite nests. Professor Ehud Meron of Ben-Gurion University of the Negev studied the fairy circles of Namibia as a case study to understand how ecosystems respond to water scarcity.

He believes that all theories today miss the connection between two reliable mechanisms essential for understanding ecosystem response: phenotypic plasticity at the individual plant level and spatial self-organization in vegetation patterns at the plant population level. Phenotypic plasticity is the ability of a plant to change its characteristics in response to the influence of the external environment.

New model and findings

Professor Meron, his postdoctoral fellows Jamie Bennett, Bidesh Bera and Michel Ferré, and colleagues Prof. Hezi Yizhaq and Stephan Getzin propose a new model that captures both the spatial pattern of water-vegetation feedback and phenotypic changes involving deep root growth to reach a wetter soil layer.

By comparing model predictions with empirical observations, they show that the link between these two mechanisms is the key to solving two important puzzles that classical theory of vegetation formation cannot explain: the formation of multi-scale fairy circles in which the matrix between fairy circles resides. It consists of small patches of vegetation along the rainfall gradient and the absence of lines and dot patterns other than discontinuity patterns, as predicted by classical theory.

Furthermore, they found that the combination of phenotypic changes at the plant level and spatial patterning at the population level can lead to many additional pathways for ecosystem response to water stress, resulting in different multi-scale patterns, all of which are significantly more resilient to water stress than other patterns. contains a phenotype.

Their findings were recently published Proceedings of the National Academy of Sciences (PNAS).

“Identifying these alternative pathways is crucial to moving fragile ecosystems from pathways of destruction to pathways of resilience,” explains Professor Meron, who recently won an ERC Synergy grant to study resilience pathways in drylands and other biomes. “This study highlights the importance of considering more elements of ecosystem complexity when addressing the question of how to prevent dysfunctional ecosystem states from emerging as a warmer, drier climate develops,” Professor Meron concludes.