Data from: Assembling the forest herb community after abandonment from agriculture: long-term successional dynamics differ with land-use history

1. Cultivation and pasturing, both historically common forms of agriculture in eastern North America, differ in their long-term environmental legacies. We ask whether successional re-assembly of the forest herb community differs between second-growth stands with contrasting agricultural histories. We predicted that herb communities would diverge through a process of environmental filtering as colonist species responded to the agricultural histories of individual sites and to underlying edaphic gradients.
2. Thirty-five second-growth stands were grouped into a replicated chronosequence of formerly cultivated and pastured sites spanning 80 years after canopy closure. Five long-established stands without signs of agricultural history were included as controls. Herbaceous vegetation and soil and environmental variables were recorded at each site.
3. Forest herb species accumulated through the chronosequence. Community composition changed through successional time, transitioning from open-forest species to shade-tolerant perennial herbs, and differed significantly between pastured and cultivated sites. A high degree of similarity among control sites suggests eventual convergence, although chronosequence sites at 80 years had not yet reached the richness and composition observed in the controls. Agricultural practices were initially distinguishable in species richness, evenness, and composition but agricultural influence receded as the stands approached 80 years.
4. Synthesis: Community assembly in post-agricultural forests appears to be a process of site-level convergence driven by gradual accumulation of species from the regional species pool, relatively rapid conformity to soil gradients, and growth of the forest stand. This is result is scale-dependent; distributions are controlled by topographic filtering at coarser and finer scales.

1. 耕作与放牧均为北美东部历史上常见的农业生产形式，二者的长期环境遗留效应存在显著差异。本研究旨在探究具有不同农业利用历史的次生林样地中，森林草本植物群落的演替重建过程是否存在差异。我们提出假设：随着定居物种响应各站点的农业利用历史与深层土壤环境梯度，草本植物群落将通过环境过滤过程发生分化。
2. 本研究选取35处次生林样地，依据林冠闭合后的时间跨度，将其划分为包含耕作与放牧历史的重复时间序列样地组，时间跨度可达80年。另纳入5处无农业利用历史的成熟林样地作为对照。对各站点的草本植被、土壤及环境变量进行了记录采集。
3. 随着时间序列推移，森林草本物种数量逐渐积累。群落组成随演替时间发生变化，从喜光林下地被物种逐步过渡到耐阴多年生草本，且放牧与耕作样地的群落组成存在显著差异。对照样地间的高度相似性提示群落最终将趋于收敛，尽管80年生的时间序列样地尚未达到对照样地的物种丰富度与群落组成水平。农业活动最初可通过物种丰富度、均匀度及群落组成加以区分，但随着样地林龄接近80年，农业活动的影响逐渐消退。
4. 综合分析：农后恢复森林的群落构建过程，本质上是由区域物种种库的逐步积累、对土壤环境梯度的快速适应以及林分生长共同驱动的站点水平收敛过程。该结果具有尺度依赖性：物种分布在粗尺度与细尺度上均受地形过滤作用调控。