The understorey harbours a substantial part of vascular plant diversity in temperate forests and plays an important functional role, affecting ecosystem processes such as nutrient cycling and overstorey regeneration. Global change, however, is putting these understorey communities on trajectories of change, potentially altering and reducing their functioning in the future. Developing mitigation strategies to safeguard the diversity and functioning of temperate forests in the future is challenging and requires improved predictive capacity. Process-based models that predict understorey community composition over time, based on first principles of ecology, have the potential to guide mitigation endeavours but such approaches are rare. Here, we review fourteen understorey modelling approaches that have been proposed during the last three decades. We evaluate their inclusion of mechanisms that are required to predict the impact of global change on understorey communities. We conclude that none of the currently existing models fully accounts for all processes that we deem important based on empirical and experimental evidence. Based on this review, we contend new models are needed to project the complex impacts of global change on forest understoreys. Plant functional traits should be central to such future model developments, as they drive community assembly processes and provide valuable information on the functioning of the understorey. Given the important role of the overstorey, a coupling of understorey models to overstorey models will be essential to predict the impact of global change on understorey composition and structure, and how it will affect the functioning of temperate forests in the future.

中文翻译：

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模拟全球变化下温带森林的林下动态——挑战和前景。

下层林带是温带森林中维管植物多样性的重要组成部分，并发挥着重要的功能作用，影响着养分循环和上层层再生等生态系统过程。然而，全球变化正在将这些下层社区置于变化的轨道上，未来可能会改变和减少它们的功能。制定缓解策略以保护未来温带森林的多样性和功能具有挑战性，需要提高预测能力。基于过程的模型根据生态学的基本原理，随着时间的推移预测林下群落组成，有可能指导缓解努力，但这种方法很少见。在这里，我们回顾了过去三年中提出的十四种林下建模方法。我们评估了它们是否包含预测全球变化对林下社区的影响所需的机制。我们得出的结论是，当前存在的模型中没有一个能够完全解释我们根据经验和实验证据认为重要的所有过程。基于这次审查，我们认为需要新模型来预测全球变化对森林下层的复杂影响。植物功能性状应该是此类未来模型开发的核心，因为它们会推动群落组装过程并提供有关下层功能的宝贵信息。鉴于上层的重要作用，下层模型与上层模型的耦合对于预测全球变化对下层组成和结构的影响至关重要，