Pettersson Susanne, Savage Van M, Nilsson Jacobi Martin
Department of Space, Earth and Environment, Chalmers University of Technology, Maskingränd 2, 412 58 Gothenburg, Sweden.
Department of Ecology and Evolutionary Biology, UCLA, Los Angeles, CA 90095, USA.
J R Soc Interface. 2020 May;17(166):20190391. doi: 10.1098/rsif.2019.0391. Epub 2020 May 13.
Dynamical shifts between the extremes of stability and collapse are hallmarks of ecological systems. These shifts are limited by and change with biodiversity, complexity, and the topology and hierarchy of interactions. Most ecological research has focused on identifying conditions for a system to shift from stability to any degree of instability-species abundances do not return to exact same values after perturbation. Real ecosystems likely have a continuum of shifting between stability and collapse that depends on the specifics of how the interactions are structured, as well as the type and degree of disturbance due to environmental change. Here we map boundaries for the extremes of strict stability and collapse. In between these boundaries, we find an intermediate regime that consists of single-species extinctions, which we call the extinction continuum. We also develop a metric that locates the position of the system within the extinction continuum-thus quantifying proximity to stability or collapse-in terms of ecologically measurable quantities such as growth rates and interaction strengths. Furthermore, we provide analytical and numerical techniques for estimating our new metric. We show that our metric does an excellent job of capturing the system's behaviour in comparison with other existing methods-such as May's stability criteria or critical slowdown. Our metric should thus enable deeper insights about how to classify real systems in terms of their overall dynamics and their limits of stability and collapse.
生态系统稳定性与崩溃这两个极端状态之间的动态转变是其特征。这些转变受到生物多样性、复杂性以及相互作用的拓扑结构和层次结构的限制，并随其变化。大多数生态研究都集中在确定系统从稳定状态转变为任何程度不稳定状态的条件——受到扰动后物种丰度不会恢复到完全相同的值。实际的生态系统可能在稳定与崩溃之间存在一个连续的转变过程，这取决于相互作用的具体结构方式，以及环境变化引起的干扰类型和程度。在此，我们绘制了严格稳定和崩溃这两个极端状态的边界。在这些边界之间，我们发现了一个由单物种灭绝组成的中间状态，我们称之为灭绝连续统。我们还开发了一种度量方法，根据诸如增长率和相互作用强度等生态可测量量，确定系统在灭绝连续统中的位置，从而量化其接近稳定或崩溃的程度。此外，我们提供了用于估计我们新度量方法的分析和数值技术。我们表明，与其他现有方法（如梅的稳定性标准或临界减速）相比，我们的度量方法在捕捉系统行为方面表现出色。因此，我们的度量方法应该能够更深入地洞察如何根据实际系统的整体动态以及其稳定和崩溃的极限对其进行分类。
