Abstract Biodiversity is fundamental for ecosystem functioning, but little is known about how function responds to biodiversity loss following habitat disturbance in natural systems. Due to the global decay of veteran trees, many associated saproxylic (i.e. deadwood-dependent) insects are considered threatened. Nevertheless, the role of habitat spatial configuration on saproxylic insect biodiversity and dead wood decomposition is poorly understood. We performed a six-year landscape-scale colonization experiment on saproxylic beetles inhabiting hollow oaks, using boxes filled with wood mould as standardized habitat patches. We placed boxes either on a hollow tree or on another tree 61–324 m from the hollows, thereby creating two habitat isolation levels. We quantified wood mould decay and biodiversity in the boxes, measuring species richness, total abundances and community-weighted mean of body mass (CWM) as an index of community functional composition. Isolation had a persistent negative effect on primary consumer biodiversity, but it only impaired decay at the beginning of the experiment. All effects were independent of landscape-level (500-m radius) habitat amount surrounding the boxes. Wood mould decay was mediated by CWM of primary consumers. Therefore function was driven by the body masses of the dominant primary consumer species but not by species numbers (richness) or individual numbers (abundance). Our experiment shows that small-scale habitat isolation leads to biodiversity loss and reduced function and indicates that habitats created by conservation efforts will be used by more saproxylic species if located within sites with a high density of veteran trees.

中文翻译：

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树洞的小规模隔离降低了腐木生物多样性和分解率

摘要 生物多样性是生态系统功能的基础，但对于自然系统中栖息地干扰后功能如何应对生物多样性丧失的情况知之甚少。由于老树在全球范围内腐烂，许多相关的腐木（即依赖枯木）昆虫被认为受到威胁。然而，栖息地空间配置对腐生昆虫生物多样性和死木分解的作用知之甚少。我们对居住在空心橡树上的腐生甲虫进行了为期六年的景观规模定植实验，使用装有木霉的盒子作为标准化的栖息地斑块。我们将盒子放在一棵空心树上或距离空心 61-324 m 的另一棵树上，从而创建了两个栖息地隔离级别。我们量化了木箱中的木霉腐烂和生物多样性，测量物种丰富度，总丰度和群落加权体重平均值 (CWM) 作为群落功能组成的指标。隔离对初级消费者的生物多样性有持续的负面影响，但它只会在实验开始时削弱衰减。所有影响都与盒子周围的景观水平（500 米半径）栖息地数量无关。木材霉菌腐烂是由初级消费者的 CWM 介导的。因此，功能是由主要消费物种的体重驱动的，而不是由物种数量（丰富度）或个体数量（丰富度）驱动的。我们的实验表明，小规模的栖息地隔离会导致生物多样性丧失和功能降低，并表明如果位于具有高密度老树的地点，通过保护工作创造的栖息地将被更多的腐木物种利用。