泥炭沼泽植物功能多样性与生态系统功能关系及机理研究

This project will be conducted in herbaceous communities distributed in mountain peatlands of northeastern China. The relationship of plant functional diversity and ecosystem function (productivity and litter decomposition) of herbaceous peatlands will be determined among different types of peatland communities in various environments. The functional diversity indices (functional richness, functional evenness and functional divergence) will be calculated based on the species richness and 11 plant traits in each community, in which the productivity (aboveground, belowground and total) and litter decomposition rate (weight loss and carbon, nitrogen, phosphorus) will be measured in 2 or 3 continuous years. The water level and temperature will be automatically recorded by instruments, and nutrients of water and soil will be collected to analyze the effect of ibiotic factors on the functional diversities, ecosystem functions and their relationships. The aims of this project are (1) to determine whether the functional diversity could explain more variance of ecosystem function than species diversity in peatland ecosystem; (2) to try to clarify whether the application of mass ratio hypothesis and diversity hypothesis in peatland ecosystem is affected by the heterogeneity of environment and/or dominant species among different communities; (3) to analyze the ecological pattern and process of the relationship of functional diversity and ecosystem function by structural equation modelling and compare the direct and indirect effects of various functional diversity indices after quantification. (4) to develop the theory of biodiversity-ecosystem function using approach of functional ecology. This project will help to understand the relationship and mechanism of biodiversity and ecosystem function, therefore to improve the theory research on community ecology, such as theories of biodiversity and community assembly. Furthermore, the research on relationship and mechanism of functional diversity and ecosystem function in peatland ecosystem has an important significance to illustrate and predict how the community structure and ecosystem function of peatland to response the change of global climate and land use pattern by altering plant trait combination. The coming results will also help to make practical instructions to protect and restore degraded peatlands.

本项目拟以我国东北山地草本泥炭沼泽生态系统为实验对象，选择不同环境条件下的多种群落类型，研究植物功能多样性与生态系统功能（群落生产力和枯落物分解）的关系。该项目拟确定影响泥炭沼泽生态系统功能的植物功能多样性指标；确定质量比假说和多样性假说在泥炭沼泽生态系统中的适用条件；从功能多样性角度丰富生物多样性-生态系统功能关系理论。该项目的研究工作有助于深入认识生物多样性-生态系统功能关系及作用机制，推动多样性理论和群落构建理论等群落生态学的理论研究。此外，泥炭沼泽群落植物功能多样性与生态系统功能关系及机理研究，对阐明和预测植物如何通过性状组合，直接和间接驱动泥炭沼泽生态系统功能响应全球气候和土地利用方式变化具有重要意义，也对管理和恢复退化沼泽植被等方面起到积极的实践指导作用。

功能多样性与生态系统功能关系的研究整合了植物性状、群落生态学和生物进化理论，开辟了生态学研究的新领域。当前研究多集中在森林和草地生态系统中。但两者关系的机制分析比较复杂，在不同群落类型和环境条件下可能表现不一，因此揭示两者关系的影响机理还需要更多样化群落数据的支持。.本项目以我国东北山地草本泥炭沼泽生态系统为对象，以植物功能多样性与生态系统功能关系为核心，研究了泥炭沼泽系统中不同类型群落的植物功能多样性、环境因素、群落生产力和枯落物分解，多种多元方法分析了功能多样性与生态系统功能的关系。.研究结果表明：（1）泥炭沼泽草本群落的地上生物量受环境因子、物种数量和功能多样性的影响。在自养的泥炭沼泽群落中，营养因子对地上生物量的影响高于其它影响因子。物种数量对地上生物量不存在显著的直接影响，其间接影响作用较弱且为负作用。与物种数量相比，植物性状的群落权重均值和Rao二次熵与群落生产力的关系更加密切。确定了植株高度和叶片氮含量的群落权重均值、叶片碳含量和比叶面积的功能分离度是影响研究区泥炭沼泽生态系统功能的主要植物功能多样性指标。（2）分析异质群落时，植物性状的群落权重均值更好解释了地上生物量的变化，而在分析同质群落时，植物性状的Rao值更好解释了生物量的变化。据此提出质量比假说适用于群落间功能性状差异较大的异质群落，而多样性假说适用于群落间功能性状差异较小的同质群落。（3）证明了生物多样性对生态系统过程的影响，不应仅归因于物种数量本身，植物性状在很大程度上决定了物种个体如何在群落水平上影响生态过程。在揭示生物多样性与生态系统功能关系时，既要考虑群落内功能性状的丰富度、分离度和均匀度等指标，也应考虑群落间上述功能多样性指标的变化程度。上述结论从功能生态学角度丰富了生物多样性-生态系统功能关系的理论研究。.该项目的研究工作有助于深入认识生物多样性-生态系统功能关系及作用机制，推动多样性理论和群落构建理论等群落生态学的理论研究。此外，泥炭沼泽群落植物功能多样性与生态系统功能关系及机理研究，对阐明和预测植物如何通过性状组合，直接和间接驱动泥炭沼泽生态系统功能响应全球气候和土地利用方式变化具有重要意义，也对管理和恢复退化沼泽植被等方面起到积极的实践指导作用。