Navigating the complexity of ecological stability

Abstract

Human actions challenge nature in many ways. Ecological responses are ineluctably complex, demanding measures that describe them succinctly. Collectively, these measures encapsulate the overall 'stability' of the system. Many international bodies, including the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services, broadly aspire to maintain or enhance ecological stability. Such bodies frequently use terms pertaining to stability that lack clear definition. Consequently, we cannot measure them and so they disconnect from a large body of theoretical and empirical understanding. We assess the scientific and policy literature and show that this disconnect is one consequence of an inconsistent and one-dimensional approach that ecologists have taken to both disturbances and stability. This has led to confused communication of the nature of stability and the level of our insight into it. Disturbances and stability are multidimensional. Our understanding of them is not. We have a remarkably poor understanding of the impacts on stability of the characteristics that define many, perhaps all, of the most important elements of global change. We provide recommendations for theoreticians, empiricists and policymakers on how to better integrate the multidimensional nature of ecological stability into their research, policies and actions.

An invariability-area relationship sheds new light on the spatial scaling of ecological stability

“…While mathematicians often define stability as the ability of a dynamical system to return to some state after a small perturbation, ecologists have used a wide array of different stability measures2417. Invariability has a number of merits that make it an appropriate starting point to investigate the spatial scaling of stability.…”

“…Invariability has a number of merits that make it an appropriate starting point to investigate the spatial scaling of stability. First of all, the goal of a stability measure is to quantify the ability of a system to withstand perturbations417. Stability thus reflects the interplay between intrinsic dynamical processes and perturbations that act upon a system.…”

“…For this purpose, invariability, which measures the magnitude of an ecosystem's response to persistent and erratic environmental perturbations18 and which can be defined consistently across levels of organization and scales131419, offers an accessible starting point. Invariability is also easy to quantify in the field, which makes it by far the most commonly used measure of stability in empirical studies17. Lastly, recent theoretical studies have demonstrated that invariability is intrinsically related to other measures of stability such as asymptotic resilience1820, Holling's resilience21, structural stability22 and persistence10.…”

Generic assembly patterns in complex ecological communities

“…Diversity was represented by two quantities: φ the fraction of species in the invader pool that survive in the assembled state, and D the inverse of the Simpson index [10]. Among the many dimensions of ecological stability [11], we focused on one measure of dynamical stability frequently employed in empirical studies: variability V , the variance in time of species abundance due to stochastic perturbations [12,13,14] (see details in Supplementary Materials). In summary:…”

Invasions of Host-Associated Microbiome Networks

“…Changing parameters can alter the stability of steady states, for example by making them suddenly unstable, whereupon the natural dynamics takes the state away to some other steady state that is stable. Most theoretical studies of ecological stability focus on stable states while empirical studies use temporal (or spatial) variability of abundance or biomass to measure stability, where communities with wildly fluctuating populations are considered less stable (Donohue et al 2016). …”