Endogenous ecosystem disturbances: implications for regional dynamics
Massé Jodoin, Julien; Guichard, Frédéric
UNIVERSITÉ MCGILL

Ecosystem dynamics can exhibit pronounced disturbance-recovery cycles resulting from environmental variability, population feedbacks, and ecosystem maturation. The disturbance regime of natural systems can influence the strength and the variability of their regional connectivity. Yet, the implications of rare and extreme spatial flows of (in)organic matter and propagules for the regional stability of ecological systems remain unresolved. Using a minimal ecosystem model of an intertidal ecosystem engineer (Mytilus spp.), we find that local feedback from ecosystem maturation can lead to rare and catastrophic fluctuations of population abundance and ecosystem resources. When expanded to a 2-patch metaecosystem, we show this disturbance regime induces a complex response of local ecosystems to matter movement and propagules dispersal. This response is characterized by a resistance to synchronization under very strong coupling, which is associated with coupled temporal modulation of the phase and the amplitude of local fluctuations. When such modulation regimes differ between patches, we observe emergent spatial heterogeneity of population abundance and ecosystem properties. Additionally, matter movement can lead to aperiodic modulation, decoupled phase and amplitude dynamics, or even point equilibrium of local systems in the presence of population-ecosystem feedbacks. Understanding the resulting dynamical regimes is not trivial as their spatial concordance, amplitude, and frequency are strong determinants of the provision and the retention of resources at the regional scale. We suggest coupled phase-amplitude modulation is a revealing signature of complex regional dynamics and could be a potent tool for understanding the implications of endogenous disturbances for ecosystem management.