Plant community composition and functional traits respond to chronic drivers such as climate change and nitrogen (N) deposition. In contrast, pulse disturbances from ecosystem management can additionally change resources and conditions. Community responses to combined environmental changes may further depend on land-use legacies. Disentangling the relative importance of these global change drivers is necessary to improve predictions of future plant communities. We performed a multifactor global change experiment to disentangle drivers of herbaceous plant community trajectories in a temperate deciduous forest. Communities of five species, assembled from a pool of 15 forest herb species with varying ecological strategies, were grown in 384 mesocosms on soils from ancient forest (forested at least since 1850) and postagricultural forest (forested since 1950) collected across Europe. Mesocosms were exposed to two-level full-factorial treatments of warming, light addition (representing changing forest management) and N enrichment. We measured plant height, specific leaf area (SLA) and species cover over the course of three growing seasons. Increasing light availability followed by warming reordered the species towards a taller herb community, with limited effects of N enrichment or the forest land-use history. Two-way interactions between treatments and incorporating intraspecific trait variation (ITV) did not yield additional inference on community height change. Contrastingly, community SLA differed when considering ITV along with species reordering, which highlights ITV's importance for understanding leaf morphology responses to nutrient enrichment in dark conditions. Contrary to our expectations, we found limited evidence of land-use legacies affecting community responses to environmental changes, perhaps because dispersal limitation was removed in the experimental design. These findings can improve predictions of community functional trait responses to global changes by acknowledging ITV, and subtle changes in light availability. Adaptive forest management to impending global change could benefit the restoration and conservation of understorey plant communities by reducing the light availability.

中文翻译：

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光照和变暖推动了森林在不同环境中下层社区的发展。

植物群落组成和功能性状对诸如气候变化和氮（N）沉积等慢性驱动因素作出反应。相反，来自生态系统管理的脉冲干扰会另外改变资源和条件。社区对综合环境变化的反应可能进一步取决于土地使用的遗产。弄清这些全球变化驱动因素的相对重要性对于改进对未来植物群落的预测是必要的。我们进行了一项多因素全球变化实验，以弄清温带落叶林中草本植物群落轨迹的驱动因素。由15种具有不同生态策略的森林草本物种组成的5种群落，它们生长在384种中观世界中，这些土壤来自欧洲各地收集的古代森林（至少自1850年以来为森林）和后农业森林（自1950年以来为森林）。中观被暴露于变暖，增光（代表不断变化的森林经营）和氮富集的两级全要素处理。我们测量了三个生长季节中的植物高度，比叶面积（SLA）和物种覆盖率。增加光的供应量，然后变暖，使该物种向一个更高的草本群落重新排序，而氮素富集或森林土地利用历史的影响却有限。治疗之间的双向相互作用以及结合种内性状变异（ITV）并未得出关于群落高度变化的其他推论。相反，在考虑ITV以及物种重新排序时，社区SLA有所不同，这突出了ITV在理解黑暗条件下叶片对养分富集的叶片形态反应方面的重要性。与我们的预期相反，我们发现有限的证据表明土地使用传统影响社区对环境变化的反应，这可能是因为在实验设计中消除了分散限制。这些发现可以通过承认ITV以及可用光的细微变化，来改善对社区功能性状对全球变化的反应的预测。适应即将发生的全球变化的适应性森林管理可以通过减少光的供应量来促进底层植物群落的恢复和保护。我们发现有限的证据表明土地使用传统会影响社区对环境变化的反应，这也许是因为在实验设计中消除了分散限制。这些发现可以通过承认ITV以及可用光的细微变化，来改善对社区功能性状对全球变化的反应的预测。适应即将发生的全球变化的适应性森林管理可以通过减少光的供应量来促进底层植物群落的恢复和保护。我们发现有限的证据表明土地使用传统会影响社区对环境变化的反应，这也许是因为在实验设计中消除了分散限制。这些发现可以通过承认ITV以及可用光的细微变化，来改善对社区功能性状对全球变化的反应的预测。适应即将发生的全球变化的适应性森林管理可以通过减少光的供应量来促进底层植物群落的恢复和保护。