Climate change and the prospects for more frequent and intense climate extremes, such as prolonged droughts, threaten many services that plant communities provide to humans. The concern is for the occurrence of community-structure changes, where less-functional species displace key ones, and species diversity is reduced. Underlying this concern is the high complexity of ecosystems, reflected in part by their hierarchy of organization levels, from the organism level to the population and community levels, and up to the ecosystem level. This complexity hampers attempts to disentangle ecosystem responses to climate extremes that involve mechanisms operating at different organization levels.In this research, we focused on the response of plant communities to prolonged droughts that couples population-level and community-level mechanisms. The population-level mechanism involves intraspecific competition that results in partial plant mortality and self-organization of plants into spatial patterns (see figure). The community-level mechanism involves interspecific interactions that result in composition shifts from species investing in growth to species investing in tolerating water stress. Using a mathematical model that captures the two mechanisms, three surprising insights have resulted: (1) spatial self-organization acts to reverse community-structure changes induced by water stress, (2) it buffers the impact of further stress, and (3) it generates multi-stability of alternative ecosystem states leading to niche differentiation and thereby offers new directions of ecosystem management that integrate the need for provisioning ecosystem services with the need to conserve community structure.
These insights highlight the need to consider essential aspects of ecosystem complexity – specifically spatial self-organization – when addressing possible responses of ecosystems to climate extremes. Ecosystem complexity provides diverse pathways of ecosystem response that mitigate environmental stresses and offers new opportunities for managing ecosystems at risk by choice of preferred pathways.
This research has been conducted in the Blaustein Institutes for Desert Research by Prof. Ehud Meron, his postdoctoral fellows Dr. Bidesh Bera and Dr. Jamie Bennett, and his former Ph.D. student, Dr. Omer Tzuk. The research has been supported by the Israel Science Foundation and has appeared this month in eLife:
Bidesh K. Bera, Omer Tzuk, Jamie J. R. Bennett, and Ehud Meron, "Linking spatial self-organization to community structure and biodiversity," eLife 10, e73819 (2021).