Schweiger Andreas H, Boulangeat Isabelle, Conradi Timo, Davis Matt, Svenning Jens-Christian
Section for Ecoinformatics and Biodiversity, Department of Bioscience, Aarhus University, Ny Munkegade 114, 8000, Aarhus C, Denmark.
Plant Ecology, Bayreuth Center for Ecology and Environmental Research (BayCEER), University of Bayreuth, 95440, Bayreuth, Germany.
Biol Rev Camb Philos Soc. 2019 Feb;94(1):1-15. doi: 10.1111/brv.12432. Epub 2018 Jun 6.
Increasing human pressure on strongly defaunated ecosystems is characteristic of the Anthropocene and calls for proactive restoration approaches that promote self-sustaining, functioning ecosystems. However, the suitability of novel restoration concepts such as trophic rewilding is still under discussion given fragmentary empirical data and limited theory development. Here, we develop a theoretical framework that integrates the concept of 'ecological memory' into trophic rewilding. The ecological memory of an ecosystem is defined as an ecosystem's accumulated abiotic and biotic material and information legacies from past dynamics. By summarising existing knowledge about the ecological effects of megafauna extinction and rewilding across a large range of spatial and temporal scales, we identify two key drivers of ecosystem responses to trophic rewilding: (i) impact potential of (re)introduced megafauna, and (ii) ecological memory characterising the focal ecosystem. The impact potential of (re)introduced megafauna species can be estimated from species properties such as lifetime per capita engineering capacity, population density, home range size and niche overlap with resident species. The importance of ecological memory characterising the focal ecosystem depends on (i) the absolute time since megafauna loss, (ii) the speed of abiotic and biotic turnover, (iii) the strength of species interactions characterising the focal ecosystem, and (iv) the compensatory capacity of surrounding source ecosystems. These properties related to the focal and surrounding ecosystems mediate material and information legacies (its ecological memory) and modulate the net ecosystem impact of (re)introduced megafauna species. We provide practical advice about how to quantify all these properties while highlighting the strong link between ecological memory and historically contingent ecosystem trajectories. With this newly established ecological memory-rewilding framework, we hope to guide future empirical studies that investigate the ecological effects of trophic rewilding and other ecosystem-restoration approaches. The proposed integrated conceptual framework should also assist managers and decision makers to anticipate the possible trajectories of ecosystem dynamics after restoration actions and to weigh plausible alternatives. This will help practitioners to develop adaptive management strategies for trophic rewilding that could facilitate sustainable management of functioning ecosystems in an increasingly human-dominated world.
人类对严重动物绝迹的生态系统施加的压力不断增加，这是人类世的特征，需要采取积极的恢复方法，以促进能够自我维持的、功能正常的生态系统。然而，鉴于经验数据支离破碎且理论发展有限，诸如营养重引入等新型恢复概念的适用性仍在讨论之中。在此，我们构建了一个将“生态记忆”概念融入营养重引入的理论框架。生态系统的生态记忆被定义为生态系统从过去动态中积累的非生物和生物物质及信息遗产。通过总结关于大型动物灭绝和重引入在广泛时空尺度上的生态影响的现有知识，我们确定了生态系统对营养重引入做出响应的两个关键驱动因素：（i）（重新）引入的大型动物的潜在影响，以及（ii）表征目标生态系统的生态记忆。（重新）引入的大型动物物种的潜在影响可根据物种特性来估计，例如人均终生工程能力、种群密度、活动范围大小以及与本地物种的生态位重叠。表征目标生态系统的生态记忆的重要性取决于：（i）大型动物消失后的绝对时间，（ii）非生物和生物周转的速度，（iii）表征目标生态系统的物种相互作用的强度，以及（iv）周围源生态系统的补偿能力。这些与目标生态系统和周围生态系统相关的特性介导了物质和信息遗产（其生态记忆），并调节（重新）引入的大型动物物种对生态系统的净影响。我们提供了关于如何量化所有这些特性的实用建议，同时强调生态记忆与历史上偶然的生态系统轨迹之间的紧密联系。借助这个新建立的生态记忆 - 重引入框架，我们希望指导未来的实证研究，以探究营养重引入和其他生态系统恢复方法的生态影响。所提出的综合概念框架还应帮助管理者和决策者预测恢复行动后生态系统动态的可能轨迹，并权衡合理的替代方案。这将有助于从业者制定营养重引入的适应性管理策略，从而促进在日益以人类为主导的世界中对功能正常的生态系统进行可持续管理。
