有机物质量介导的农田土壤线虫群落及生态功能研究

Sustainable agriculture relies on whether soil biodiversity provides ecosystem service. Compared to the concept of species diversity, functional diversity of soil community is recognized more relevant to ecosystem functioning. But there is a knowledge gap on the functional roles of functional traits of arable soil community. Organic amendment is considered as a foundation of modern multi-functional agriculture via promoting soil organic matter level. Previous studies stressed the organic amendment quantity in shaping soil communities and ecosystem functioning. Considering almost all agricultural activities would affect the chemical composition of organic amendment (here called ‘quality’ as decomposer was concerned), a functional trait-based conceptual integration framework was presented connecting the traits of organic amendment quality, soil biota and ecosystem functioning. Here, this proposal mainly aimed to fill the two knowledge gaps: one is lack of understanding the key drivers of soil food web in agricultural soil ecosystem and another is the key functional traits that determine ecosystem functioning. In order to fullfill this, we have three research goals: (1) investigate the responses of soil nematode community to organic amendment across a broad quality gradient and disentangle the key drivers of soil food web; (2) elucidate the subsequent functional feedback by nematode community mediated by the quality of organic amendment and clarify the inherent mechanisms involved in decomposition and nitrogen cycling. Integrating the functional trait-based approach, representative organic amendments were selected from the red soil region. Soil nematode community analysis is performed to indicate soil food web state. Complementary and well-directed field plots, field microcosm, laboratory experiments and sythesizing meta-analysis are going to be conducted to explore the responses and effects of soil nematode assemblage mediated by different organic amendments. Functional traits of soil organic matter, soil microbial community and nematode assemblage, and decomposition process and nitrogen transformation rate were comprehensively examined to testify the hypothesis that organic matter quality would modify soil biological traits and furthermore ecosystem functioning. Together, this proposal will develop a conceptual integration of key drivers of soil food web and key functional traits of nematode assemblage in feedback on ecosystem functioning. Besides, it will help clarify the mechanism of manipulating the quality of organic amendment on ecosystem services. Furthermore, it will also provide bases for combining soil biodiversity management and protection into soil ecological engineering technology for the ecological agriculture or green agriculture.

农业的持续发展离不开土壤生物多样性的贡献，与物种多样性相比，土壤生物群落的功能多样性可能与生态功能的联系更密切。然而，迄今缺乏对农田土壤生物功能性状地位的认识。通过有机物料替代部分化肥和提高土壤生物功能是减少对化石燃料依赖的最重要措施。有机物料通过提高土壤有机质水平而成为建立多功能农业的基础。与有机物料数量特征相比，几乎所有农业活动都会改变有机物质量，但迄今仍缺乏农业有机物质量与生态功能关系的认识。基于有机物质量影响土壤环境、驱动土壤生物群落、进而生态功能的过程假说，本项目遵循功能性状思路，选择红壤区不同有机物料，以土壤线虫群落指示食物网结构，综合野外定位、原位分解、缩微系统等实验途径和整合分析，通过测定土壤环境（土壤有机质）、生物（微生物和线虫）功能性状、生态功能（分解和氮素转化），解析有机物质量-土壤生物群落-生态功能的关系，明确土壤线虫群落变化的驱动因子和功能反馈的关键性状，揭示有机物质量对农田土壤生态功能的调控机制。预期结果也为生态农业或绿色农业发展中将土壤生物多样性的管理和保护纳入土壤生态工程技术提供依据。

农业离不开土壤生物多样性，与物种多样性相比，功能多样性可能与生态功能的联系更密切。然而，迄今缺乏对农田土壤生物功能性状地位的认识。有机物料通过提高土壤有机质成为多功能农业的基础。与有机物料数量特征相比，几乎所有农业活动都会改变有机物质量，但迄今仍缺乏农业有机物质量与生态功能关系的认识。基于有机物质量影响土壤环境、驱动土壤生物群落、进而生态功能的过程假说，本项目遵循功能性状思路，选择红壤区不同有机物料，以土壤线虫群落指示食物网结构，综合野外定位、原位分解、缩微系统等实验途径和整合分析，通过测定土壤环境（土壤有机质）、生物（微生物和线虫）功能性状、生态功能（分解和氮素转化），解析有机物质量-土壤生物群落-生态功能的关系，明确土壤线虫群落变化的驱动因子和功能反馈的关键性状，揭示有机物质量对生态功能的调控机制。主要研究包括：基于野外定位实验阐明有机物种类（质量）对土壤生物群落的影响，明确土壤线虫群落组成变化的关键驱动因子；借助野外分解管分解试验，研究土壤线虫群落对生态功能的影响，初步分析直接和间接影响因子；最后研究了有机物质量与线虫群落交互作用对生态功能的影响及机制。.本项目结合食物网理论和代谢理论，系列研究以线虫食物网分析为基础，量化了施肥措施对土壤食物网的能流结构和多功能性的影响，发现有机肥支持下的生物多样性促进了土壤食物网的能流通量和均匀度。在研究过程中，发现相较于线虫多样性，食物网能流结构复杂性的提高不仅反映长期施用有机肥的影响，且更好地解释生态系统多功能性的变化，这为进一步了解多营养级生物相互作用和功能地位提供了一个新的概念框架。总之，培育土壤生物多样性尤其是营养级结构复杂性的有机管理措施，将有助于生态系统多功能性服务的发挥。考虑到未来环境变化下的物种非随机损失，在食物网水平上，探究营养级和能流之间的联系对于土壤可持续管理至关重要。