Data from: Threshold dynamics in plant succession after tree planting in agricultural riparian zones.

1. Trajectories of plant communities can be described by different models of plant succession. While restoration projects have traditionally been framed into a clementsian (gradual continuum model) or gleasonian approach (relay floristics model), alternative succession models developed recently may better represent restoration trajectories. Threshold dynamics succession model, which predicts an abrupt species turnover after an environmental threshold is crossed, has never been used in a restoration context. This model might, however, better describe shifts in plant competitive ranking and facilitation interactions during species turnover.
2. Fifty-three riparian zones, planted with trees 3 to 17 years prior to sampling, and 14 natural riparian forests were studied in two agricultural watersheds of southeastern Québec (Canada). The cover of vegetation strata was assessed at the site-scale, and the cover of plant species was estimated in a total of 784 one square meter plots. Canopy cover was measured stereoscopically for each plot.
3. As revealed by Principal Response Curves (PRC) and broken stick models, herbaceous species composition was stable during the first 12-13 years after tree planting, but then abruptly shifted. This two-step pattern in species turnover followed the increase of canopy cover after tree planting. Once canopy cover passed a threshold of ca 40%, plant succession started and led to the re-establishment of forest communities 17 years after planting.
4. During herbaceous species turnover, the cover of ecological groups changed significantly toward covers of natural riparian forests: shade tolerant species generally increased while light-demanding and exotic species decreased. Vegetation structure was also significantly affected by tree planting: tree and shrub cover increased while monocot cover decreased.
5. Tree planting efficiently restored herbaceous forest communities in riparian zones by inducing a species turnover mediated by light availability corresponding to a threshold dynamics in plant succession. Fostering and monitoring canopy closure in tree-planted riparian zones should improve restoration outcomes and adaptive management design. The innovative statistical approach of this study aiming to identify succession patterns and their associated theoretical models can be applied to any type of ecosystem undergoing restoration around the world to bridge the gap between science and management.14-Mar-2016

1. 植物群落的演替轨迹可通过不同的植物演替模型加以阐释。传统上，生态修复项目常被归为克莱门茨演替模型（Clementsian，渐进连续体模型）或格莱松演替途径（Gleasonian，接力植物区系模型），而近年来开发的新型演替模型或能更精准地刻画修复轨迹。阈值动态演替模型（Threshold dynamics succession model）可预测当越过环境阈值后会发生物种的突然更替，该模型此前从未被应用于生态修复场景中，但它或能更清晰地描述物种更替过程中植物竞争等级与促进作用互作的动态变化。
2. 研究区域位于加拿大魁北克东南部的两个农业流域，共调查了53处造林年限为3至17年的河岸带样地，以及14处天然河岸林。以样地为尺度评估植被层盖度，并在总计784个1平方米样方中估算植物物种盖度；同时采用立体测量法测定每个样方的冠层盖度。
3. 主响应曲线（Principal Response Curves，PRC）与断棒模型分析结果显示，造林后前12~13年，草本植物群落组成保持稳定，随后发生突变。这种两步式的物种更替模式与造林后冠层盖度的增加趋势相契合：当冠层盖度越过约40%的阈值后，植物演替启动，并在造林17年后促使森林群落得以重建。
4. 在草本植物物种更替过程中，植物功能群盖度朝着天然河岸林的盖度特征发生显著变化——耐阴物种盖度总体上升，而喜光物种与外来物种盖度下降。造林活动同样显著改变了植被结构：乔木与灌木盖度上升，而单子叶植物盖度下降。
5. 造林通过诱导由光照可获得性介导的物种更替（契合植物演替的阈值动态特征），有效实现了河岸带草本森林群落的生态修复。因此，在造林河岸带中促进并监测冠层闭合，可优化修复效果与适应性管理方案。本研究采用的创新性统计方法（用于识别演替模式及其关联的理论模型）可推广至全球各类正在开展修复的生态系统，以弥合科学研究与管理实践之间的鸿沟。2016年3月14日