Retention forestry is increasingly adopted as an alternative to clearcutting practices and involves retaining structural and compositional complexity (e.g., living and dead trees) from preharvest to postharvest. Past studies have examined the role of retention forestry in supporting various ecosystem functions and biodiversity, whilst its microclimate buffering capacity has been largely neglected. We investigated the microclimates and the underlying mechanisms of retention forests relative to clearcuts and old forests in a boreal forest landscape in central Sweden. We found that both air temperature and vapour pressure deficit (VPD) differed significantly between the forest types. Old forests consistently exhibited the most buffered forest microclimates, followed by retention forests, while clearcuts displayed the lowest. Basal area and canopy cover were identified as the key determinants influencing air temperature and VPD across the forest types. Retention practices can also impact a stand's microclimates. Specifically, maintaining diverse tree species had the potential to lower the stand's maximum temperature, given its positive association with canopy cover. Large volumes of lying deadwood were found to be negatively correlated with both basal area and canopy cover, likely contributing to increased maximum temperatures. Furthermore, standing deadwood directly lowered the maximum temperature within forest stands. Finally, edge effects were observed in the retention forests, with south-facing edges experiencing significantly higher maximum temperature and VPD compared to north-facing edges and forest interiors. These south-facing edge effects were positively associated with the difference in lying deadwood volumes between forest edges and interiors. Our findings support the positive influence of retention practices on a stand's microclimate buffering, achieved through preserving diverse tree species, standing deadwood, and implementing measures to prevent severe wind-induced tree mortality, particularly in south-facing edges (e.g. creating south-facing buffer zones). Forest managers and policy makers can utilize these results to minimize the climate-change impacts on below-canopy biodiversity and functioning.

中文翻译：

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保留林业增强了北方森林的小气候缓冲

保留林业越来越多地被采用作为皆伐做法的替代方法，并涉及从采前到采后保留结构和成分的复杂性（例如，活树和死树）。过去的研究考察了保留林业在支持各种生态系统功能和生物多样性方面的作用，但其小气候缓冲能力在很大程度上被忽视了。我们研究了瑞典中部北方森林景观中保留森林相对于砍伐森林和老森林的小气候和潜在机制。我们发现不同森林类型之间的气温和蒸气压赤字 (VPD) 存在显着差异。古老的森林始终表现出最缓冲的森林小气候，其次是保留林，而砍伐的森林小气候则最低。断面积和冠层覆盖被确定为影响森林类型气温和 VPD 的关键决定因素。保留措施也会影响展台的微气候。具体来说，维持树种多样化有可能降低林分的最高温度，因为它与树冠覆盖呈正相关。人们发现大量的枯木与断面积和树冠覆盖度呈负相关，可能导致最高温度升高。此外，直立的枯木直接降低了林内的最高温度。最后，在保留林中观察到边缘效应，与朝北的边缘和森林内部相比，朝南的边缘经历了明显更高的最高温度和 VPD。这些朝南的边缘效应与森林边缘和内部之间的枯木体积差异呈正相关。我们的研究结果支持保留措施对林分小气候缓冲的积极影响，这是通过保护不同的树种、直立枯木以及采取措施防止严重的风引起的树木死亡而实现的，特别是在朝南的边缘（例如创建朝南的缓冲区）区）。森林管理者和政策制定者可以利用这些结果来最大限度地减少气候变化对树冠下生物多样性和功能的影响。