Multi-Level Ecosystem Response to Climate Change

Abstract

Ecosystem response to drier climates is likely to employ stress-relaxation mechanisms operating at different levels of ecological organization. At the individual level, a plant can change its phenotype, e.g., from a shallow root plant to a deep root plant to reach a moister soil layer. At the population level, plants can self-organize in spatial patterns, a process that involves partial plant mortality and increased water availability to remaining plants. At the community level, shifts from fast-growing species to stress-tolerant species can occur. These mechanisms are naturally coupled, but their interplay has hardly been studied. In this talk, I will present model studies of the interplay between phenotypic changes and vegetation patterning and between vegetation patterning and community re-assembly.  I will show that phenotypic transitions from shallow-roots to deep-roots plants can result in multiscale vegetation patterns and increased resilience to drier climates. I will further show that spatial patterning can result in a homeostatic plant community that keeps its composition and diversity unchanged, despite the development of a drier climate, because of spatial re-patterning. Understanding pathways of ecosystem response, where mechanisms operating at different organization levels act in concert, is essential for assessing the actual resilience of ecosystems at risk and devising management practices to evade tipping points.