Wende Beate, Gossner Martin M, Grass Ingo, Arnstadt Tobias, Hofrichter Martin, Floren Andreas, Linsenmair Karl Eduard, Weisser Wolfgang W, Steffan-Dewenter Ingolf
Department of Animal Ecology and Tropical Biology, Biocenter, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
Terrestrial Ecology Research Group, Department of Ecology and Ecosystem Management, School of Life Sciences Weihenstephan, Technische Universität München, Hans-Carl-von-Carlowitz-Platz 2, 85354 Freising-Weihenstephan, Germany.
Proc Biol Sci. 2017 May 17;284(1854). doi: 10.1098/rspb.2017.0198.
The specialization of ecological networks provides important insights into possible consequences of biodiversity loss for ecosystem functioning. However, mostly mutualistic and antagonistic interactions of living organisms have been studied, whereas detritivore networks and their successional changes are largely unexplored. We studied the interactions of saproxylic (deadwood-dependent) beetles with their dead host trees. In a large-scale experiment, 764 logs of 13 tree species were exposed to analyse network structure of three trophic groups of saproxylic beetles over 3 successional years. We found remarkably high specialization of deadwood-feeding xylophages and lower specialization of fungivorous and predatory species. During deadwood succession, community composition, network specialization and network robustness changed differently for the functional groups. To reveal potential drivers of network specialization, we linked species' functional traits to their network roles, and tested for trait matching between plant (i.e. chemical compounds) and beetle (i.e. body size) traits. We found that both plant and animal traits are major drivers of species specialization, and that trait matching can be more important in explaining interactions than neutral processes reflecting species abundance distributions. High network specialization in the early successional stage and decreasing network robustness during succession indicate vulnerability of detritivore networks to reduced tree species diversity and beetle extinctions, with unknown consequences for wood decomposition and nutrient cycling.
生态网络的专业化为生物多样性丧失对生态系统功能可能产生的后果提供了重要见解。然而，目前大多研究的是生物体之间的互利和拮抗相互作用，而碎屑食性网络及其演替变化在很大程度上尚未得到探索。我们研究了依赖枯木生存的甲虫与其死亡寄主树之间的相互作用。在一项大规模实验中，暴露了764根来自13个树种的原木，以分析依赖枯木生存的甲虫三个营养组在3年演替过程中的网络结构。我们发现，以枯木为食的食木甲虫具有非常高的专业化程度，而食真菌和捕食性物种的专业化程度较低。在枯木演替过程中，不同功能组的群落组成、网络专业化程度和网络稳健性变化各异。为了揭示网络专业化的潜在驱动因素，我们将物种的功能性状与其在网络中的角色联系起来，并测试了植物（即化学化合物）和甲虫（即体型）性状之间的性状匹配情况。我们发现，植物和动物性状都是物种专业化的主要驱动因素，而且在解释相互作用方面，性状匹配可能比反映物种丰度分布的中性过程更为重要。演替早期阶段的高网络专业化程度以及演替过程中网络稳健性的降低，表明碎屑食性网络易受树种多样性减少和甲虫灭绝的影响，这对木材分解和养分循环的后果尚不清楚。
