Towards a rapid assessment of multifunctionality and multidiversity in tree biodiversity experiments using coarse woody debris as model system

粗木质碎屑是全球森林生态系统的重要组成部分。它代表了一个重要的碳库和营养库，促进了木生生物的生物多样性，影响了侵蚀，并成为野火的燃料。对物种丰富的亚热带森林中的CWD动态知之甚少，对树木多样性的作用也知之甚少。生物多样性可能通过改变分解者微环境(通过多样性与林分结构之间的联系)、基质质量(通过树种的特性)以及腐生昆虫的多样性和丰度来影响CWD的分解速率和储量。为了探索树木多样性在CWD分解上的特征，我们提出了野外观测和实验相结合的方法：(1)我们跟踪了源于最近一次降雪的标记原位CWD的命运。(2)在主要试验和NILEx试验中，将在比较研究的地块中放置不同微生物和昆虫可及性的标准化CWD(垃圾袋，高架位置)，以理清树木多样性、林分结构和非生物因素的作用。(3)以20个树种为材料，研究了CWD分解与木材性状的关系。这些实验将与其他关于碳、氮动态和昆虫多样性的子项目紧密结合。通过这个项目，我们希望发现一条生物多样性如何影响森林生态系统功能的新途径。

Coarse woody debris (CWD) is an important component of forest ecosystems throughout the world. It represents a significant carbon and nutrient pool, promotes biodiversity of wood-dwelling organisms, influences erosion and serves as a fuel for wildfire. Little is known about CWD dynamics in species-rich subtropical forests and hardly anything is known about the role of tree diversity. Biodiversity may affect decomposition rates and stocks of CWD by altering the decomposer microenvironment (via the link between diversity and stand structure), the substrate quality (via tree species’ traits) and the diversity and abundance of saproxylic insects. To explore the signature of tree diversity on CWD decomposition we propose a combination of field observations and experiments: (1) We follow the fate of labeled in situ CWD originating from a recent snowbreak. (2) Standardized CWD varying in accessibility for microbes and insects (litter bags, elevated position) will be deposited in the comparative study plots, in the main experiment and in the NILEx experiment, to disentangle the roles of tree diversity, stand structure, and abiotic factors. (3) The relationship between CWD decomposition and wood traits is investigated using material from 20 tree species. The experiments will be closely integrated with the other subprojects on C and N dynamics and insect diversity. With this project we expect to uncover a novel pathway of how diversity affects ecosystem functioning in forests.