The Resilience and Resistance of an Ecosystem to a Collapse of Diversity

Abstract

Diversity is expected to increase the resilience of ecosystems. Nevertheless, highly diverse ecosystems have collapsed, as did Lake Victoria’s ecosystem of cichlids or Caribbean coral reefs. We try to gain insight to this paradox, by analyzing a simple model of a diverse community where each competing species inflicts a small mortality pressure on an introduced predator. High diversity strengthens this feedback and prevents invasion of the introduced predator. After a gradual loss of native species, the introduced predator can escape control and the system collapses into a contrasting, invaded, low-diversity state. Importantly, we find that a diverse system that has high complementarity gains in resilience, whereas a diverse system with high functional redundancy gains in resistance. Loss of resilience can display early-warning signals of a collapse, but loss of resistance not. Our results emphasize the need for multiple approaches to studying the functioning of ecosystems, as managing an ecosystem requires understanding not only the threats it is vulnerable to but also pressures it appears resistant to.

Cover versus recovery: Contrasting responses of two indicators in seagrass beds

“…Measuring relative recovery or even recovery rates seems the most appropriate method to relate to experimental and easily collectable data. The reduction in recovery rates in the sheltered site in the presence of nutrient addition, suggests that nutrient addition would reduce the resilience of the system, putting the system closer to its bifurcation point (Wissel, 1984;Scheffer and Carpenter, 2003;van Nes and Scheffer, 2007;Scheffer et al, 2009;Downing et al, 2012). The same is observed at the exposed site, be it to a less strong extent.…”

Relation between stability and resilience determines the performance of early warning signals under different environmental drivers

“…The motivation for ongoing studies on critical slowing down indicators, among many other warning signals, is to identify their potential as well as their limitations (26) and develop a toolbox of indicators. Investigations into other properties [e.g., resistance (49), reactivity (50,51), invasiveness, etc.] and their relations will help us address a fundamental question: how to measure the "stability" of a system (52,53).…”

Helping nature help us: Transforming disaster risk reduction through ecosystem management

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