Linking biodiversity to ecosystem functioning in forest ecosystems: biotic drivers of wood decomposition

将生物多样性与森林生态系统中的生态系统功能联系起来：木材分解的生物驱动因素

• 批准号: 335346150
• 负责人: Professor Dr. Jörg Müller
• 金额: --
• 依托单位: Ökologische Station Fabrikschleichach
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2017
• 资助国家: 德国
• 起止时间: 2016-12-31 至 2019-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/335346150?language=en
• 关键词: Linking; biodiversity; ecosystem; functioning; forest

Massive declines in taxonomic diversity due to increasing pressure by land use can impair ecosystem functions. Decomposition of dead wood is a key process in forests with regard to, e.g., carbon and nutrient cycling, but the increasing need for land and forest products has led to decreasing populations of forest species worldwide. The overall process, driven by complex interactions between several decomposer taxa, mainly wood-decaying fungi and saproxylic insects, however, remains still poorly understood and particularly more specific questions such as the role of species richness of decomposers for wood decomposition has not been answered so far. Even for fungi, no clear overall relation between species richness and decomposition could be derived as both positive and negative relations have been observed. A further complicating factor is certain decomposer groups can contribute to wood decomposition directly, e.g. by consumption of wood by saproxylic beetles, but also indirectly via other decomposer groups, as e.g. saproxylic beetles vectoring wood-decaying fungi. To disentangle the role of species richness and functional diversity of saproxylic beetles, a mesocosm experiment has been set up successfully in the Bavarian Forest National Park in 2015, manipulating 190 saproxylic beetle communities spanning independent gradients of species richness and functional diversity (body size and excavating function). The proposed project aims at measuring the contribution of the manipulated beetle fauna to wood decomposition by an innovative method, namely X-ray computed tomography (CT). In contrast to traditional sample-based methods, a complete piece of wood can be scanned non-destructively within seconds and with a resolution sufficiently high to conduct quantitative analyses of wood density that allow detecting even small differences in wood decomposition. In addition, we aim to measure decomposition by wood-decaying fungi (ergosterol and enzyme contents) and to apply next-generation DNA sequencing of fungal communities on saproxylic beetles and inside experimental logs to record precisely the colonization of wood by fungi. By linking decomposition and wood-decaying fungi to characteristics of single beetle species and beetle communities, we will be able to disentangle direct and indirect effects of saproxylic beetles on wood decomposition. In specific, we want to test the following hypothesis: (H1) Functional diversity of saproxylic beetle communities is more important for the speed of wood decomposition than beetle species richness; (H2) The larger the beetle species and the deeper their galleries, the stronger their direct and indirect contribution to decomposition; (H3) The composition of fungal communities vectored by saproxylic beetles is beetle species specific, and (H4) wood decomposition by fungi starts from beetle galleries.

由于土地使用的压力越来越大，分类多样性大幅度下降，可能损害生态系统的功能。分解枯木是森林中的一个关键过程，例如，森林物种的数量减少，但对土地和森林产品的需求日益增加，导致全世界森林物种数量减少。整个过程，几个分解类群，主要是木材腐烂真菌和safetylic昆虫之间的复杂的相互作用，然而，仍然知之甚少，特别是更具体的问题，如物种丰富度的作用，木材分解的分解者还没有得到回答。即使是真菌，物种丰富度和分解之间没有明确的整体关系，可以得出的积极和消极的关系已经观察到。另一个复杂的因素是某些分解者群体可以直接促进木材分解，例如通过由腐皮甲虫消耗木材，但也可以通过其他分解者群体间接促进木材分解，例如腐皮甲虫引导木材腐烂真菌。为了解开物种丰富度和功能多样性的作用，2015年在巴伐利亚森林国家公园成功地建立了一个中型生态系统实验，操纵了190个物种丰富度和功能多样性（体型和挖掘功能）独立梯度的物种丰富度和功能多样性。拟议的项目旨在通过一种创新方法，即X射线计算机断层摄影术，测量被操纵的甲虫动物群对木材分解的贡献。与传统的基于样品的方法相比，可以在几秒钟内对完整的木材进行非破坏性扫描，并且分辨率足够高，可以对木材密度进行定量分析，从而可以检测木材分解的微小差异。此外，我们的目标是测量木材腐烂真菌（麦角固醇和酶含量）的分解，并应用下一代的真菌群落的DNA测序的safetylic甲虫和内部实验日志，以准确记录木材真菌的殖民化。通过将分解和木材腐烂真菌与单一甲虫物种和甲虫群落的特征联系起来，我们将能够解开腐皮甲虫对木材分解的直接和间接影响。（H1）功能多样性比物种丰富度对木材分解速度的影响更大：（H2）甲虫种类越多、坑道越深，对木材分解的直接和间接贡献越大;（H3）腐皮甲虫所引导的真菌群落组成具有甲虫种特异性，（H4）真菌分解木材的起始位置是甲虫廊道。