Understanding variation in tree regeneration among species and sites, and how well forest size class distribution (seedlings, saplings, and trees) portends long-term species compositional change, may assist managing forests during contemporary global change rapidly altering forests, such as after invasion by introduced pests. In northwestern Ohio, one of the North American regions longest invaded by emerald ash borer (EAB, ), we 1) examined variation in size class abundance among tree species and sites in 22 forested wetlands in 2018 and 2021; and 2) assessed how closely size class distribution of tree species in 2005, at the onset of EAB invasion before trees died, forecasted observed forest change during the next 17 years. In 2018 and 2021, three major groups of tree species emerged with respect to their frequency across size classes: 1) species commonly in all three, or at least two, size classes on a site, 2) species frequent in only one size class, which varied but was often seedlings, and 3) species almost always present only as trees, with little advance regeneration. Shade tolerance correlated with species occurring in all three size classes. Among sites in 2018 and 2021, abundance of regeneration and similarity of species composition across size classes varied between years (largely from fluctuations in seedlings) and with site factors. Sites with the least regeneration had high soil available water capacity and high cover of graminoids. On long-term sites after the onset of EAB invasion in 2005, all seedling-to-sapling and sapling-to-tree advancements recorded through 2021 were from species already present in 2005, and only shade-tolerant species (e.g., ) advanced. Results suggest that there is substantial variation in advance regeneration availability among species and sites in forested wetlands across the EAB-invaded landscape. Portions of this variability were structured into well-demarcated groups of similarly responding species and sites, were associated with species traits such as shade tolerance and site factors such as soil texture, and were prognostic of forest changes within the first two decades after EAB invasion.

中文翻译：

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树木更新的物种和景观变化以及白蜡虫入侵森林湿地17年的变化

了解物种和地点之间树木再生的差异，以及森林大小类别分布（幼苗、幼树和树木）预示着长期物种组成变化的程度，可能有助于在当代全球变化迅速改变森林的情况下管理森林，例如在森林入侵之后引入害虫。在俄亥俄州西北部，北美白蜡螟 (EAB, ) 入侵时间最长的地区之一，我们 1) 在 2018 年和 2021 年检查了 22 个森林湿地的树种和地点之间尺寸等级丰度的变化；2) 评估了 2005 年，在树木死亡之前 EAB 入侵开始时，树种的大小等级分布与预测未来 17 年观察到的森林变化的密切程度。2018 年和 2021 年，就​​其在尺寸类别中的频率而言，出现了三类主要树种：1）在一个地点的所有三个或至少两个尺寸类别中常见的物种，2）仅在一个尺寸类别中常见的物种，其种类各不相同，但通常是幼苗，并且 3) 物种几乎总是仅以树木的形式出现，几乎没有提前再生。耐荫性与所有三个尺寸级别的物种相关。在 2018 年和 2021 年的地点中，不同大小类别的再生丰度和物种组成的相似性因年份（主要来自幼苗的波动）和地点因素而异。再生最少的地点具有较高的土壤可用水容量和较高的禾本科植物覆盖率。在 2005 年 EAB 入侵开始后的长期站点上，截至 2021 年记录的所有幼苗到树苗和树苗到树木的进展均来自 2005 年已存在的物种，并且只有耐荫物种（例如 ）发生进展。结果表明，在 EAB 入侵景观中的森林湿地中，不同物种和地点的提前再生可用性存在很大差异。这种变异性的一部分被构造为具有相似响应的物种和地点的明确划分的群体，与耐荫性等物种特征和土壤质地等地点因素相关，并且是EAB入侵后前二十年内森林变化的预测。