Data from: Genetic consequences of selection cutting on sugar maple (Acer saccharum Marshall)

Selection cutting is a treatment that emulates tree-by-tree replacement for forests with uneven-age structures. It creates small openings in large areas and often generates a more homogenous forest structure (fewer large leaving trees and defective trees) that differs from old-growth forest. In this study, we evaluated whether this type of harvesting has an impact on genetic diversity of sugar maple (Acer saccharum Marshall). Genetic diversity among seedlings, saplings and mature trees was compared between selection cut and old-growth forest stands in Québec, Canada. We found higher observed heterozygosity and a lower inbreeding coefficient in mature trees than in younger regeneration cohorts of both forest types. We detected a recent bottleneck in all stands undergoing selection cutting. Other genetic indices of diversity (allelic richness, observed and expected heterozygosity and rare alleles) were similar between forest types. We concluded that the effect of selection cutting on the genetic diversity of sugar maple was recent and no evidence of genetic erosion was detectable in Québec stands after one harvest. However, the cumulative effect of recurring applications of selection cutting in bottlenecked stands could lead to fixation of deleterious alleles, and this highlights the need for adopting better forest management practices.择伐（Selection cutting）是一种针对异龄林结构森林的经营措施，其运作逻辑为模拟单株树木的自然更替过程。该措施会在大面积林分内营造小型林隙，通常会形成相较于原始林（Old-growth forest）更为均质的林分结构——具体表现为留存的大径木与缺陷木数量更少。 本研究以加拿大魁北克省的择伐林与原始林林分为研究对象，针对糖枫（Acer saccharum Marshall）的实生苗、幼树与成熟个体的遗传多样性开展对比分析，以评估该类采伐方式对糖枫遗传多样性的影响。 研究结果显示，两类林分中的成熟个体均较更新世代幼树表现出更高的观测杂合度（observed heterozygosity）与更低的近交系数（inbreeding coefficient）；所有经择伐处理的林分均检测到近期瓶颈效应（bottleneck）。两类林分的其余遗传多样性指标（包括等位基因丰富度（allelic richness）、观测杂合度、期望杂合度（expected heterozygosity）及稀有等位基因（rare alleles））均无显著差异。 本研究表明，择伐对糖枫遗传多样性的影响仅为短期效应，单次采伐后的魁北克省林分中未检测到遗传侵蚀（genetic erosion）迹象。然而，在已发生瓶颈效应的林分中重复开展择伐所产生的累积效应，可能会引发有害等位基因（deleterious alleles）的固定，这一结果凸显了优化森林经营措施的迫切需求。