Some comments about resilience: From cyclicity to trajectory, a shift in living and nonliving system theory

Abstract

What is a resilient system? From an (eco)geomorphic point of view, the answer is complex owing to the polysemy of the term resilience and its wide range of uses from one discipline to another. In all cases, this concept provides a way of thinking of rivers' future in terms of persistence, sometimes cyclically, sometimes with respect to evolutionary trajectories, and with or without humans as internal parameters. The popularity of resilience in ecology and amongst the social-ecological systems community, following the pioneer works of Holling (1973), has influenced the way we consider the concept in geomorphology and creates misunderstanding and debates. In this contribution, we retrace the evolution of the term over time, introduce the different types of resilience, resilience to pulse, ramp or press disturbances, and show its implicit presence in (fluvial) system theory. Both schools of thought highlight trajectory patterns of systems with positive visions of Earth's future. We then explore some challenging issues in ecogeomorphology related to resilience when considering system responses to discrete events and to a set of internal or external drivers.