论文标题：Regime shifts occur disproportionately faster in larger ecosystems

期刊：Nature Communications

作者：Gregory S. Cooper, Simon Willcock et al.

发表时间：2020/03/10

DOI：10.1038/s41467-020-15029-x

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《自然-通讯》发表的一项建模研究Regime shifts occur disproportionately faster in larger ecosystems发现，亚马孙热带雨林和加勒比海珊瑚礁等大型脆弱生态系统的崩溃一旦触发，过程可能只需几十年的时间。

建模框架的图形表示。来源：Cooper, G.S., Willcock, S. & Dearing, J.A.

在生态学中，系统转变是指生态系统稳态经历的大规模、持久且往往是预期之外的改变，可能受其到达“临界点”后的反馈循环驱动。研究人员认为，系统转变的频率会在气候变化和环境退化的作用下增加；然而，生态系统崩溃的速度和规模之间的关系尚未得到充分认识。这一信息或有助于发现合适时机，采取适应性管理策略来减少生态破坏。

系统面积与系统转变时间之间的经验关系。来源：Cooper, G.S., Willcock, S. & Dearing, J.A.

英国南安普顿大学的John Dearing和同事分析了4个陆地、25个海洋、13个淡水生态系统转变报告中的数据，发现较大生态系统经历的系统转变比较小的生态系统更慢。但是，随着生态系统规模的扩大，崩溃所需要的额外时间会减少，导致它们的崩溃会相对变快。作者利用计算机模型支持的统计学关系进行了估计，发现亚马孙规模的生态系统（约550万平方公里）一旦触发，可能会在49年左右的时间里崩溃。而加勒比海珊瑚礁规模的系统（约2万平方公里）一旦开始，可能只要15年的时间就会崩溃。

作者总结表示，人类需要为生态系统转变速度超出此前预估做好准备。

摘要：

Regime shifts can abruptly affect hydrological, climatic and terrestrial systems, leading to degraded ecosystems and impoverished societies. While the frequency of regime shifts is predicted to increase, the fundamental relationships between the spatial-temporal scales of shifts and their underlying mechanisms are poorly understood. Here we analyse empirical data from terrestrial (n = 4), marine (n = 25) and freshwater (n = 13) environments and show positive sub-linear empirical relationships between the size and shift duration of systems. Each additional unit area of an ecosystem provides an increasingly smaller unit of time taken for that system to collapse, meaning that large systems tend to shift more slowly than small systems but disproportionately faster. We substantiate these findings with five computational models that reveal the importance of system structure in controlling shift duration. The findings imply that shifts in Earth ecosystems occur over ‘human’ timescales of years and decades, meaning the collapse of large vulnerable ecosystems, such as the Amazon rainforest and Caribbean coral reefs, may take only a few decades once triggered.

（来源：科学网）