Understanding the long‐term success of ecosystem restoration following invasive plant removal is challenging. Long‐term experiments are costly and slow to yield results, while management decisions must often be made immediately. Alternatively, retrospective studies can leverage contrasting historical management strategies to provide insight into long‐term vegetation responses. We used a retrospective approach to evaluate how management techniques and site characteristics affected re‐establishment of an invasive shrub, Rhamnus cathartica (common buckthorn), in midwestern North America. Following removal, buckthorn re‐establishes rapidly from resprouts and seeds, so follow‐up control is required but often lacking. We hypothesized that revegetating using native herbaceous seed after removing buckthorn increases herbaceous cover that competitively suppresses buckthorn regeneration, to a degree. We surveyed 46 management units at 24 sites. Revegetated units had higher herbaceous cover, lower buckthorn cover, and half the ratio of buckthorn:herbaceous cover compared with unseeded units. These effects, although considerable on average, were detected against a background of high variance. Seeding increased herbaceous cover and reduced buckthorn relative abundance more strongly on less acidic, more clayey soils and where follow‐up herbicide was not applied. Additional variability in revegetation impacts may have arisen from buckthorn resprouts having a head‐start on planted seeds. Only one site had both seeded and unseeded management units. This lack of blocking—a common challenge in retrospective studies—reduced statistical power. This investigation illustrates how retrospective studies can offer relatively inexpensive first assessments of long‐term effects of management techniques; for more rigorous inference, researchers can partner with managers to conduct long‐term experiments.

中文翻译：

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植被减慢沙棘的入侵：回顾评估管理技术的优势和局限性

了解去除入侵植物后生态系统恢复的长期成功具有挑战性。长期实验成本高昂，而且产生结果的速度缓慢，而管理决策通常必须立即做出。另外，回顾性研究可以利用不同的历史管理策略来洞察长期的植被响应。我们使用回顾性方法来评估管理技术和场地特征如何影响侵入性灌木鼠李（Rhamnus cathartica）的重建（常见的沙棘），位于北美中西部。去除后，沙棘从芽苗和种子中迅速恢复，因此需要后续控制，但常常缺乏。我们假设去除沙棘后使用天然草木种子进行再植被会增加草木覆盖，从而在一定程度上竞争性地抑制沙棘的再生。我们调查了24个站点的46个管理部门。与非播种单位相比，植被单元的草本覆盖率更高，沙棘覆盖率更低，而沙棘：皮脂覆盖率的一半为一半。这些影响，尽管平均而言相当可观，但在高方差的背景下被检测到。在酸度较低，黏土较多的土壤上以及未施用后续除草剂的土壤上，播种可增加草层覆盖并更有效地降低沙棘的相对丰度。沙棘芽苗对栽种种子具有先发优势，可能还会对植被重新产生影响。只有一个站点既有种子管理单元又有非种子管理单元。缺乏障碍（回顾性研究中的常见挑战）降低了统计能力。这项调查说明了回顾性研究如何能够提供相对廉价的管理技术长期效果的初步评估；为了进行更严格的推断，研究人员可以与管理人员合作进行长期实验。这项调查说明了回顾性研究如何能够提供相对廉价的管理技术长期效果的初步评估；为了进行更严格的推断，研究人员可以与管理人员合作进行长期实验。这项调查说明了回顾性研究如何能够提供相对廉价的管理技术长期效果的初步评估；为了进行更严格的推断，研究人员可以与管理人员合作进行长期实验。