Data from: Effects of management on aquatic tree-hole communities in temperate forests are mediated by detritus amount and water chemistry

1. Arthropod communities in water-filled tree-holes may be sensitive to impacts of forest management, for example via changes in environmental conditions such as resource input. 2. We hypothesized that increasing forest management intensity negatively affects arthropod abundance and richness and shifts community composition and trophic structure of tree-hole communities. We predicted that this shift is caused by reduced habitat and resource availability at the forest stand scale as well as reduced tree-hole size, detritus amount and changed water chemistry at the tree-hole scale. 3. We mapped 910 water-filled tree-holes in two regions in Germany and studied 199 tree-hole inhabiting arthropod communities. 4. We found that increasing forest management intensity indeed significantly reduced arthropod abundance and richness in water-filled tree-holes. The most important indirect effects of management intensity on tree-hole community structure were the reduced amounts of detritus for the tree-hole inhabiting organisms and changed water chemistry at the tree-hole scale, both of which seem to act as a habitat filter. Although habitat availability at the forest stand scale decreased with increasing management intensity, this unexpectedly increased local arthropod abundance in individual tree-holes. However, regional species richness in tree-holes significantly decreased with increasing management intensity, most likely due to decreased habitat diversity. We did not find that the management-driven increase in plant diversity at the forest stand scale affected communities of individual tree-holes, for example via resource availability for adults. 5. Our results suggest that management of temperate forests has to target a number of factors at different scales to conserve diverse arthropod communities in water-filled tree holes.

1. 积水树洞（water-filled tree-holes）中的节肢动物群落（Arthropod communities）对森林经营活动的干扰可能较为敏感，这类影响可通过资源输入等环境条件的变化得以体现。
2. 我们提出如下假说：森林经营强度（forest management intensity）的提升会对节肢动物丰度与物种丰富度产生负面影响，并改变树洞群落的组成结构与营养结构（trophic structure）。我们进一步预测，该群落结构改变源于林分尺度（forest stand scale）下生境与资源可获得性的降低，以及树洞尺度（tree-hole scale）下树洞体积减小、枯落物（detritus）量减少与水化学性质改变。
3. 我们在德国的两个研究区域内标记了910个积水树洞，并对其中199个栖息于树洞的节肢动物群落开展了调查研究。
4. 研究结果显示，森林经营强度的提升确实会显著降低积水树洞中的节肢动物丰度与物种丰富度。经营强度对树洞群落结构最关键的间接影响，体现为树洞尺度下供栖息生物利用的枯落物量减少、水化学性质改变，这两类因素均可作为生境过滤（habitat filter）因子发挥作用。尽管林分尺度下的生境可获得性随经营强度提升而下降，但该变化却意外提升了单个树洞中的节肢动物局部丰度。然而，随着森林经营强度增加，树洞群落的区域物种丰富度显著降低，这大概率源于生境多样性的下降。我们未发现林分尺度下经营活动驱动的植物多样性提升会对单个树洞的群落产生影响，例如通过为成虫提供资源的途径。
5. 本研究结果表明，温带森林的经营活动需针对不同尺度下的多项调控要素进行优化，以保护积水树洞中的多样节肢动物群落。