Managing forests intensively for timber production can homogenize forest structure and, in turn, alter species richness and functional composition of native species communities. Retention forestry, the practice of retaining structural elements during timber harvest, can increase species diversity in recently harvested forests, but its effect on functional trait diversity is less understood. We used a broad-scale, replicated experiment to evaluate the effect of five tree retention patterns on species and functional trait diversity of ground beetles (Family: Carabidae) within early-seral production forests in the Pacific Northwest, USA. We found no evidence for differences in carabid species or functional trait richness among treatments when considering species present in retention patches and adjacent clear-cuts. However, we found evidence for lower taxonomic and functional trait variation between carabid communities present in retention patches and those present in clear-cut areas of stands when retention was allocated to several small patches. Lower levels of functional trait variation in stands with several small patches were due to specialized predators found less often in small retention patches than in aggregated or riparian retention patches. Our findings indicate that relative to single large or riparian-associated patches, small retention patches functioned similarly to clear-cuts within harvested forests and several small patches did not increase species or functional trait richness. At current levels of retention in the region, allocation of trees to a single upland patch or split between riparian and upland patches can increase variation in ground beetle taxonomic and functional composition within harvested forests.

中文翻译：

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不同保留树模式对地面甲虫（鞘翅目：Carabidae）分类和功能多样性的影响

为木材生产而集中管理森林可以使森林结构均质化，进而改变本地物种群落的物种丰富度和功能组成。保留林业，即在木材采伐期间保留结构元素的做法，可以增加最近砍伐的森林中的物种多样性，但其对功能性状多样性的影响却鲜为人知。我们使用大规模重复实验来评估五种树木保留模式对美国太平洋西北部早期血清生产森林中地甲虫（科：Carabidae）的物种和功能性状多样性的影响。在考虑保留斑块和相邻的清除地中存在的物种时，我们没有发现证据表明处理之间的carabid 物种或功能性状丰富度存在差异。然而，我们发现，当保留地分配给几个小块时，存在于保留斑块中的甲虫群落与存在于林分清晰区域的链甲群落之间的分类学和功能特征差异较低的证据。具有几个小斑块的林分的功能性状变异水平较低是由于在小块保留斑块中比在聚集或河岸保留斑块中发现的专门捕食者更少。我们的研究结果表明，相对于单个大斑块或河岸相关斑块，小块保留斑块的功能类似于采伐森林中的砍伐，几个小斑块没有增加物种或功能特征的丰富度。以该地区目前的保留水平，