量化多样性对木质残体分解的影响

项目名称： 量化多样性对木质残体分解的影响

项目编号： No.31470546

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 生态学

项目作者： Rhett Daniel Harrison

作者单位： 中国科学院昆明植物研究所

项目金额： 86万元

中文摘要： 随着全球生物多样性加速丧失，多样性和生态系统功能之间的关系日益成为人们研究的热点。枯木是森林碳库的重要组成部分,其分解在全球碳循环中发挥着不容忽视的作用,而目前人们对木材分解作用还知之甚少。多样性主要通过生境结构、木材的化学和物理性质、分解者群落三个方面影响木材分解。本研究拟开展三种互补的野外实验。实验1：自然监测两种木材，分别估测其在不同自然干扰梯度下的分解率；实验2：人工模拟自然环境，监测与实验1同种木材，区分林层和凋落物对分解的影响；实验3：人工监测25种木材，量化木材性质和系统发育对分解的影响。另外，土壤分解者群落（真菌群落和中型动物群）构成将通过DNA第二代测序获得。本研究从生物多样性角度探讨其对木材分解的影响。首次从景观尺度研究木材分解，首次利用遮阴棚凋落物床组区分生物和非生物因子在分解中的作用，并首次量化了多样性对木材分解的影响。研究结果将大大加深人类对相关领域的认识。

中文关键词： 多样性；分解；分解者群落；木材性质；系统发育

英文摘要： Given high rates of global biodiversity loss, the relationship between diversity and ecosystem functioning is of critical concern and an active area of theoretical enquiry. Dead wood accounts for a significant proportion of forest carbon pools (up to 40%) and wood decomposition is a non-trivial component of the global carbon cycle. However, the decomposition of woody debris is poorly understood and one of the largest remaining sources of uncertainty in global climate models. Wood decomposition is predominantly mediated by fungi, and the rate of decomposition is influenced by climate, substrate quality, and the responses of the decomposer community to these factors. Hence, diversity may affect wood decomposition through (i) habitat structure and its effect on microclimatic conditions on the ground, (ii) the chemical and physical properties of the wood, and (iii) the composition of the decomposer community. Moreover, the decomposition of woody debris is a successional process with different species performing distinct roles in the decomposition of substrates. We have established three complementary field experiments to assess the role of diversity in the decomposition of woody debris. In Experiment 1, we are incubating logs of two species, with low and high density wood, respectively, across a natural disturbance gradient from mature forest to degraded grassland. In Experiment 2, we are incubating the same two species in a mesocosm experiment designed to separate the effects of habitat structure and litter conditions. We used shade-cloth to simulate three levels of canopy cover and six litter-bed treatments were constructed from soil and leaf litter collected from plots selected from across the disturbance gradient. In Experiment 3, we are incubating logs of 25 tree species selected from across the higher plant phylogeny to assess the effects of wood traits and phylogeny on decomposition. In these experiments, we are monitoring mass (density) loss over 4 years. In addition, we measure respiration monthly. To monitor the composition of the decomposer community, we collect wood samples from each log and soil samples from the litter-beds every six months. These samples will be analysed using next generation sequencing to determine the fungal communities and soil mesofauna. As novel experiments on the role of biodiversity in an important and poorly understood ecosystem process, we expect these results to generate several important publications. This will be the first study to investigate wood decomposition at a landscape scale, the first study to use a shade house/litter-bed mesocosm to experimentally separate abiotic and biotic factors affecting decomposition, and the first study to quantify the effects of wood traits on decomposition across a wide functional and phylogenetic sample of species.

英文关键词： diveristy;decomposition;decomposer community;wood traits;phylogeny