Fire suppression has increased stand density and risk of severe, stand‐replacing wildfire in lower elevation dry conifer forests of western North America, threatening ecological function. The U.S. Forest Service’s Collaborative Forest Landscape Restoration Program (CFLRP) aims to mitigate impacts to ecological function, while mandating effectiveness monitoring to verify restoration success. Expected benefits include improved conditions for biodiversity, but relatively few empirical studies evaluate restoration effects on biodiversity. We applied the Integrated Monitoring in Bird Conservation Regions program to survey birds in relation to CFLRP treatments along the Colorado Front Range in 2015–2017. We employed hierarchical models to analyze species occupancy and richness at 1972 points nested within 141 1‐km² grid cells. Our objectives were to investigate (1) species occupancy relationships with treatments at local (point) and landscape (grid) spatial scales, (2) potential mechanisms for treatment relationships considering species and treatment relationships with forest structure and composition (i.e., habitat relationships), and (3) treatment and habitat relationships with species richness. The data supported positive and negative point‐level treatment relationships, suggesting uneven species distributions between treated and untreated points. At the grid scale, however, we only found positive species relationships with percent area treated, and accordingly, grid‐level species richness increased with treatment extent. Potential mechanisms for treatment relationships included treatments generating foraging opportunities for aerial insectivores by opening the canopy, improving conditions for ground‐associated species by increasing herbaceous growth, and limiting opportunities for shrub‐nesting species by reducing shrub cover. Landscape‐scale patterns suggest CFLRP treatments can benefit avian communities by generating habitat for open‐forest species without necessarily eliminating habitat for closed‐forest species. Our results provide evidence for a commonly expected but rarely verified pattern of increased species richness with forest heterogeneity. We suggest restoration treatments will most benefit forest bird diversity by reducing canopy cover, encouraging herbaceous ground cover, limiting ladder fuel species, and encouraging shrub diversity in canopy openings, while maintaining some dense forest stands on the landscape.

中文翻译：

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干燥的针叶林恢复有益于科罗拉多前锋鸟类社区。

灭火抑制增加了林分密度，并在北美西部较低海拔的干针叶林中造成了严重的，可替代林分的野火，威胁了生态功能。美国森林服务局的森林景观协作计划（CFLRP）旨在减轻对生态功能的影响，同时要求进行有效性监控以验证恢复成功。预期的收益包括改善生物多样性的条件，但是相对较少的经验研究评估了恢复对生物多样性的影响。我们应用了“鸟类保护区综合监测”计划，以调查2015-2017年科罗拉多前线沿岸地区与CFLRP处理相关的鸟类。我们使用分层模型分析了1972年1月²日内141点嵌套的物种的占有率和丰富度网格单元。我们的目标是调查（1）物种在当地（点）和景观（网格）空间尺度上与处理的占用关系，（2）考虑物种和与森林结构和组成的处理关系（即栖息地关系）的处理关系的潜在机制。 （3）处理和栖息地与物种丰富度的关系。数据支持阳性和阴性点级治疗关系，表明治疗点和未治疗点之间物种分布不均。然而，在网格规模上，我们仅发现与处理面积百分比呈正相关的物种关系，因此，网格级别的物种丰富度随处理程度的增加而增加。处理关系的潜在机制包括：通过打开树冠为空中食虫提供觅食机会的处理，通过增加草本植物的生长来改善与地面相关物种的条件，以及通过减少灌木覆盖来限制灌木嵌套物种的机会。景观尺度的格局表明，CFLRP处理可以通过为开放森林物种创造栖息地而不必为封闭森林物种创造栖息地而使鸟类社区受益。我们的结果提供了一个普遍预期但很少得到验证的，随着森林异质性增加物种丰富度的模式的证据。我们建议通过减少冠层覆盖，鼓励草本地面覆盖，限制梯形燃料的种类，恢复处理将最有利于森林鸟类的多样性，