东祁连山高寒草地退化过程中“土-草-微生物”互作机制研究

In lately 30 years, more problems about ecological and environmental have been reported worldwide. An example from China that haze weather has become a daily one right here in large part of China makes people feel "ecological crisis" is nearly to come. Therefore, many of research have been focused on "Ecological security". Qilian national nature reserve is located in the coastal area of Neimenggu-Xinjiang plateau, loess plateau and qinghai-tibet, known as the mountain "ice source reservoir". It can be as an ecological shelter for northwest even whole China. But recent years the grassland degradation is serious, the latest research shows that its ecological conditions in "very unsafe" state. So it is urgent to research and protect the ecological environment.. In ecological system of grassland, microbes play a very important role for material cycle and soil fertility, and affect plant growth and development. At the same time, soil environment and vegetation the microorganism have influent microbes’ life. Therefore, to explore relationship and internal mechanism among vegetation, soil and microbes is particularly important.. The project will focus on illustrating relationship and interaction mechanism among vegetation, soil and microbes based on investigation, measurement and analysis characters of different degradation degree of grassland vegetation, soil and microbial community of Qilian national nature reserve areas. And it will provide theoretical basis and technological support, in the view of “plant –soil- microbes”, for Qilian mountains grassland ecosystem conservation and restoration.

近30年来，全球生态和环境问题多发，保护生态已成人们关注的焦点。祁连山地处青藏、蒙新和黄土高原交汇地带，被誉为高山“冰源水库”，对于保障西北乃至全国生态安全具有十分重要地位。但该区草地退化严重，最新研究表明其处在生态状况“很不安全”的状态。系统地研究和保护该区生态环境已刻不容缓。. 草地生态系统中，微生物影响物质循环与土壤肥力，进而影响植物生长发育。同时，微生物受土壤环境和植被影响。因此，研究“植被—土壤—微生物”之间相互关系对于探索系统内在机制尤为重要。. 项目以东祁连山高寒草地为主，运用现代生物学技术，通过调查、测定和分析不同退化程度草地植被、土壤及微生物特性及其变化规律，结合气象资料，系统研究和分析高寒生态脆弱区微生物群落与植被和土壤相互关系及互作机制，以期从“土—草—微生物”视野，分析草地退化机理，为该区草地生态系统保育及恢复工程提供理论依据和科技支撑。

针对草地退化的现状和问题，已在高寒草地的退化特征和退化机理方面做了大量的研究，但这些研究主要从“植被-土壤”或“土壤-微生物”等视角进行研究，但是将“植被-土壤-微生物”结合起来作为一个整体，深入研究草地退化的机理尚不明确。因此，本项目以祁连山高寒退化草地为研究对象，以空间尺度代替时间尺度的方法，解析草地退化过程中植被、土壤特性和土壤微生物群落变化规律，阐明祁连山高寒草地退化过程中“植被-土壤-微生物”之间的互作关系。主要研究结果为：祁连山高寒草地中优势物种以莎草、珠芽蓼、赖草为主；在草地退化过程中，植被高度、地上生物量、盖度呈现出降低趋势；植物功能群以杂类草为主，莎草科次之，禾本科最少，莎草科和禾本科呈现出降低趋势，杂类草呈现出升高趋势；高寒草地退化过程中，土壤pH和电导率呈升高趋势，SOC、TP、TN、AP、NO3--N、NH4+-N和AN含量呈现出降低趋势；土壤酶活性（过氧化氢酶、蔗糖酶、碱性磷酸酶、脲酶、纤维素酶）和土壤微生物量（MBC、MBN、MBP）含量均呈现出降低趋势；高寒退化草地中占主导优势的细菌群落为变形菌门，放线菌门，酸杆菌门，芽单胞菌门，绿弯菌门和厚壁菌门；占主导优势的真菌群落为Streptophyta，子囊菌门，担子菌门，球囊菌门和Chordata；占主导优势的古菌群落为广古菌门，奇古菌门，深古菌门和泉古菌门，但在不同退化草地土壤中微生物群落的相对丰度各异；PCoA和NMDS分析发现，祁连山高寒退化草地退化过程中，土壤微生物群落在不同退化程度草地中差异较大；多组比较分析表明，祁连山退化草地中有显著性差异的菌群主要为硝化螺旋菌门、Candidatus_Tectomicrobia和奇古菌门；LefSe分析表明，在祁连山不同退化草地中，土壤微生物群落差异显著，总体呈现出细菌>真菌>古菌；总之，在祁连山高寒草地退化过程中，植物、土壤和土壤微生物之间相互作用，相互影响。本项目研究内容为祁连山高寒草地生态系统的恢复和管理保护提供参考依据和实践指导。