Abstract Retention forestry intends to promote biodiversity by retaining deadwood and tree-related microhabitats. Simultaneously, production forests undergo major structural changes by conversion into near-natural forests. As insect biomass is declining, it is important to understand how insect communities respond to management-related changes in forest structure. While some structural elements, such as deadwood, are studied extensively, three-dimensional forest structure is often neglected. Terrestrial laser scanning offers new approaches to quantify three-dimensional structure but their suitability has not been evaluated with field-based insect surveys. To test how insect communities respond to forest structure, we examined insects from window traps from 122 sites in the Black Forest. For total insect abundance and for the seven most abundant taxa, we related deadwood, microhabitats, various conventional stand properties and novel remote sensing-based indices for vegetation structure to total and taxon-specific abundances. Additionally, we assessed the influences of these structural elements on community composition. Total insect abundance and abundances of most taxa were positively related to multi-layered stands, as derived from remote sensing techniques. Furthermore, each taxon responded to some additional forest structural elements. Higher tree diameter, canopy gap fraction and share of deciduous trees increase abundances of the predominantly herbivorous taxa Heteroptera, Sternorrhyncha and Auchenorrhyncha. Community composition was influenced by mean tree diameter and share of deciduous trees. Neither tree-related microhabitats nor deadwood diversity had a detectable effect on insect abundance. We conclude that more elements of forest structure than previously acknowledged are related to insect populations. In particular, multi-layered forest stands have higher insect abundances in the midstorey. The current conversion in continuous-cover forestry in Europe from even-aged, often conifer-dominated forests to uneven-aged, mixed species stands can therefore increase the abundance of a wide range of insect taxa and is possibly one strategy to halt insect decline in forests.

中文翻译：

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管理森林中的昆虫丰度受益于多层植被

摘要 保留林业旨在通过保留枯木和与树木相关的微生境来促进生物多样性。同时，生产林通过转变为近天然林而发生重大结构变化。随着昆虫生物量的下降，了解昆虫群落如何应对森林结构中与管理相关的变化非常重要。虽然对枯木等一些结构元素进行了广泛的研究，但经常忽略了三维森林结构。地面激光扫描提供了量化三维结构的新方法，但尚未通过实地昆虫调查评估其适用性。为了测试昆虫群落对森林结构的反应，我们检查了来自黑森林 122 个地点的窗户陷阱中的昆虫。对于昆虫总丰度和七个最丰富的分类群，我们将枯木、微生境、各种常规林分特性和基于植被结构的新型遥感指数与总丰度和特定分类群丰度相关联。此外，我们评估了这些结构元素对群落组成的影响。来自遥感技术的昆虫总丰度和大多数分类群的丰度与多层林分呈正相关。此外，每个分类群都对一些额外的森林结构元素做出反应。较高的树木直径、冠层间隙分数和落叶乔木的份额增加了主要食草类群异翅目、胸口科和 Auchenorrhyncha 的丰度。群落组成受平均树木直径和落叶树份额的影响。与树木相关的微生境和枯木多样性都对昆虫丰度没有可检测的影响。我们得出的结论是，森林结构的元素比以前承认的更多，与昆虫种群有关。特别是多层林分在中间层的昆虫丰度更高。目前欧洲的连续覆盖林业从均匀年龄、通常以针叶树为主的森林转变为不均匀年龄、混合物种林分，因此可以增加各种昆虫类群的丰度，并且可能是阻止昆虫减少的一种策略。森林。多层林分在中层昆虫丰度较高。目前欧洲的连续覆盖林业从均匀年龄、通常以针叶树为主的森林转变为不均匀年龄、混合物种林分，因此可以增加各种昆虫类群的丰度，并且可能是阻止昆虫减少的一种策略。森林。多层林分在中层昆虫丰度较高。目前欧洲的连续覆盖林业从均匀年龄、通常以针叶树为主的森林转变为不均匀年龄、混合物种林分，因此可以增加各种昆虫类群的丰度，并且可能是阻止昆虫减少的一种策略。森林。