Abstract

Tropical forests host a remarkable proportion of global arthropod diversity. Yet, arthropod communities living in tropical forests are still poorly studied, particularly for dry forests of Eastern Africa. The aim of this study was to analyse community structures, species richness and relative abundances of insects across a heterogeneous forest consisting of various forest types. We collected insects in the lower canopies with light traps across the Arabuko Sokoke forest, part of the East African coastal forest biodiversity hotspot in southeast Kenya. Sampling was conducted across three forest types and along the forest edge. In total we collected > 250,000 individuals. We grouped these individuals into orders, and beetles into (sub)families. Representatives of the taxonomically well-known beetle families Cerambycidae, Tenebrionidae and Scolytinae were further determined to species level. We subsequently classified these groups into guilds according to their ecological requirements and life-histories. Relative abundances of arthropods strongly differed among taxonomic groups and forest types. Evenness was highest in the heterogeneous natural Brachystegia forest type. The mixed forest type and the forest edges showed intermediate degrees of evenness, while the structurally homogenous Cynometra forest showed comparatively low degrees of evenness.

Implications for insect conservation

We found that taxonomic and guild compositions strongly differed among the forest types. Our findings reveal that structural heterogeneity of a forest is the major driver of insect diversity, community composition, and relative abundance. Our study underlines that the preservation of all three forest types is crucial to maintain the complete diversity of arthropods across all taxonomic groups.

中文翻译：

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整个非洲热带森林生物多样性热点地区的昆虫多样性

摘要

热带森林占全球节肢动物多样性的很大一部分。然而，对生活在热带森林中的节肢动物群落的研究仍然很少，特别是对于东部非洲的干旱森林而言。这项研究的目的是分析由各种森林类型组成的非均质森林中昆虫的群落结构，物种丰富度和相对丰度。我们在下部冠层收集了昆虫，并在阿拉木图Sokoke森林（位于肯尼亚东南部的东非沿海森林生物多样性热点地区）上设置了光阱。在三种森林类型和沿森林边缘进行了抽样。我们总共收集了超过250,000个人。我们将这些个体按顺序分组，将甲虫分为（子）家族。分类学上著名的甲虫科天牛科的代表，ene科和S科进一步确定到物种水平。随后，我们根据他们的生态要求和生活史将它们分为行会。节肢动物的相对丰度在生物分类群和森林类型之间存在很大差异。均匀度最高的是异质自然Brachystegia森林类型。混交林类型和林边缘显示出中等程度的均匀度，而结构同质的Cynometra森林则显示出较低的均匀度。

对昆虫保护的意义

我们发现森林类型之间的分类学和行会组成存在很大差异。我们的发现表明，森林的结构异质性是昆虫多样性，群落组成和相对丰度的主要驱动力。我们的研究强调，保护所有三种森林类型对于维持所有生物分类群中节肢动物的完全多样性至关重要。