【作者】 郭丽娜；

【导师】 曹成有；

【作者基本信息】 东北大学 ， 生态学， 2012， 硕士

【摘要】 土壤盐渍化是土地荒漠化和影响草地生产力以及生物多样性的重要因素。科尔沁沙地是我国典型的农牧交错区,近年来草甸草地普遍出现盐渍化现象,对草地生产力造成较大影响。为探讨草地盐渍化过程对草地土壤理化性质、生物活性和生物多样性的影响,本研究选择不同盐渍化程度(轻度、中度和重度)的草地为研究对象,通过样地设置、野外调查和室内分析,研究了草地盐渍化过程中植物多样性和土壤理化性质的变化；采用Biolog ECO微孔板培养研究了盐渍化对土壤微生物碳源代谢功能多样性的影响；同时采用PCR-DGGE技术研究了盐渍化过程对土壤微生物16S rDNA基因多样性的影响。结果表明,随着盐渍化程度的加剧(土壤pH值和含盐量提高),植物多样性、地上生物量、土壤的全氮、速效氮、全磷、速效钾、有机质和含水量等均呈明显的下降趋势；土壤微生物生物量C、N的含量显著降低,土壤脲酶、蛋白酶、磷酸单酯酶、脱氢酶、硝酸还原酶和多酚氧化酶活性显著降低；Biolog ECO微孔板的分析表明,随着盐渍化程度的加剧土壤微生物对碳源利用的整体能力、碳源利用种类及利用程度均有显著差异(P<0.05),草地土壤微生物AWCD值表现为：轻度盐渍化>中度盐渍化>重度盐渍化,表明盐渍化对草地土壤微生物群落的功能产生较大影响。盐渍化过程对土壤微生物遗传多样性也产生一定影响,土壤微生物16S rDNA基因多样性指数随着草地盐渍化的加剧而呈现一定的增加趋势,而在优势度指数和均匀度指数方面没有显著差异；微生物群落组成未发生明显变化,优势种相同。本地区三种不同盐渍化程度的草地土壤中主要以不动杆菌属(Acinetobacter)、假单胞菌属(Pseudomonas)、寡养单胞菌属(Stenotrophomonas)、莫拉克斯氏菌属(Moraxella nonliquefaciens)等细菌为优势类群,重度盐渍化草地中芽孢杆菌科(Bacillaceae)也是优势菌之一。更多还原

【Abstract】 Salinization is one of importance factors on soil desertification, productivity and biodiversity of grassland. In the Horqin sandy land, a typical pastoral meadow of China, salinization has widely taken place, correspondingly resulting in the dramatic decrease of grassland productivity. In order to understand the effects of soil salinization on grassland soil properties, biological activities and biodiversity, degraded grassland with different salinization levels were selected as objects in this study. Based on field investigation and laboratory analysis, vegetation diversity and soil characteristics were analyzed in grassland. Furthermore, we adopted Biolog ECO microplate culture to learn the impact of soil salinization on functional diversity of soil microbial carbon source metabolism, as well as16S rDNA gene diversities of soil microbe via PCR-DGGE technique.The results showed that plant diversity, aboveground biomass, soil total nitrogen, available nitrogen, total phosphorus, potassium, organic matter and moisture content decreased significantly with the increase of salinization level. Soil microbial biomass C and N, and the activities of urease, protease, phosphomonoesterase, dehydrogenase, nitrate reductase and polyphenol oxidase decreased significantly as well. Significant differences of capacity, source, and type of carbon utilization in ECO microplate among the three grasslands were found (P<0.05). AWCD value of soil microbe changed with the different salinization levels, with the order as:light salinization> moderate salinization>heavy salinization, indicating that the function of soil microbial community was significantly affected by the salinization. Furthermore, with the increasing of salinization level,16S rDNA gene diversity index has an increase tread, while dominance index and evenness index did not change. The dominant species of the three grassland was almost the same. Acinetobacter, Pseudomonas, Moraxella nonliquefaciens are the dominant bacteria and widely distributed in the degraded grassland, and Bacillaceae is also one of dominant taxa in the heavy salinized grassland.更多还原