【作者】 郭永盛；

【导师】 李俊华；

【作者基本信息】 石河子大学 ， 植物营养学， 2011， 硕士

【摘要】 本研究通过温室模拟试验和野外试验相结合,研究施氮肥对荒漠草原植物物种多样性、土壤微生物种群多样性、土壤微生物功能多样性和土壤微生物遗传多样性的影响,探讨不同量的氮肥添加和不同年限施肥对不同气候条件的荒漠草原生物多样性的影响,从而根据不同的气候类型,利用合理的施肥量和施肥方式去改善退化的荒漠草原生物多样性,为改善荒漠草原土壤质量,提高荒漠草原地上生物量提供理论支持,本研究的主要结论如下：(1)施氮肥改变了新疆荒漠草原植物群落物种组成和群落中的优势种,显著增加了地上部分植物的干物质生物量,降低了物种丰富度和Shannon多样性指数、Shannon均匀度指数和Margalef物种丰富度指数,但是连续2年施氮肥使荒漠草原地上部分植物干物质生物量的增加量会逐渐降低,并且物种丰富度和物种多样性的减少趋势会变缓。说明施氮肥可以增加荒漠草原植物干物质生物量,降低植物群落多样性。(2)施氮肥可以显著的促进土壤中真菌、放线菌和细菌的数量,连续2年施氮肥更能有利于土壤中三大类微生物的生长与繁殖。土壤中三大类微生物都随着土壤深度的增加而减少,随着施肥时间的延长而先增加后减少,随着施肥量的增加呈现先增加后减低的趋势。并且土壤中三大类微生物与土壤的地理条件和性质有关,降水量高的地区微生物种群数量多,降水量小的地区微生物种群数量少。不同降水量草地对尿素施用的响应不同,降水丰富的草地土壤中微生物对氮肥的响应大,降水量少的草地响应小。说明适量施氮肥可以增加土壤微生物种群多样性。(3)施氮肥能够显著增加荒漠草原土壤微生物生物量碳氮,促进土壤中脲酶、蛋白酶、蔗糖酶、碱性磷酸酶、多酚氧化酶和过氧化氢酶的活性,增加土壤微生物对碳源的利用能力。土壤微生物量碳、氮、除多酚氧化酶活性外的其他五种酶都是随土壤深度的增加而减少,多酚氧化酶活性在土壤的中层(10-30cm)最大,其中微生物量、脲酶、蛋白酶、蔗糖酶和碱性磷酸酶的活性随施肥时间的增加呈现先增加后降低趋势,多酚氧化酶和过氧化氢酶的活性随时间的增加呈上升趋势。不同降水量草地对尿素施用的响应不同,降水丰富的草地,施用尿素后土壤不同层次酶活性很快变化,而降水较少草地响应较慢。说明适量施氮肥可以增加土壤微生物功能多样性。(4)施肥可以明显增加土壤亚硝酸细菌和氨氧化细菌的DGGE条带数,并且连续两年施肥更有利于这两种细菌DGGE条带的增加,同时,施肥还可以增加土壤亚硝酸氧化细菌和氨氧化细菌的香农指数、均匀度指数和稳定性指数,说明施氮肥可以增加硝化细菌的生物群落多样性。更多还原

【Abstract】 Greenhouse simulation experiment and wild field experiment were carried out to study effects of nitrogen(N) fertilizition on desert grassland plant, soil microbial species diversity, and population diversity, soil microbial function diversity and soil microbial genetic diversity of desert grassland in xinjiang. Different amount of N fertilizer were added in different three climatic conditions soils to research the desert grassland ecological diversity, and evaluate the effects of the climate type, N fertilization. There would be a better way to improve the desert grassland ecosystem diversity, soil quality, ground biomass. The study would provide theoretical support with main conclusions as follows:(1) N fertilization changed desert grassland plant community species composition and the advantage of plant on desert grassland in Xinjiang. It significantly increased the ground biomass of dry matter and reduced the species richness and diversity index, Shannon evenness index and Margalef richness index. Grass biomass of ground were increased slower with 2 years N fertilization than 1 year fertilization, and the species richness and diversity decreased slower too. Result showed that grass biomass were increased but plant community diversity were decreased with N fertilization.(2) N fertilization significantly improved numbers of soil bacteria, fungi, and actinomycetes. Soil microbial reproducted more with with 2 years N fertilization than 1 year fertilization. Numbers of soil microbial were decreased with soil depth, but were increased at the beginning and then decreased with increase of days after N fertilization and N application rates in the three soils. Numbers of soil microbial in higher precipitation were more than lower precipitation soil. Efficiency of N fertilization on soil microbial in higher precipitation area were more than lower precipitation area. Result showed that application of nitrogen could increase Numbers of soil microbial and soil microbial diversity.(3) N fertilization significantly promoted soil microbial biomass N and carbon, and soil urease, protease, invertase,alkaline phosphatase, polyphenol oxidase activities were significantly increased. Carbon sources utilization ability of soil microbes were increased with N application. The microbial biomass and the enzyme activities except polyphenol oxidase were decreased with soil depth, polyphenol oxidase activity in the soil 10-30cm were largest than other depth. The microbial biomass, urease, protease, invertase and alkaline phosphatase activities were increased at the beginning and then decreased with increase of days after N fertilization in the three soils, but polyphenol oxidase and catalase activities were increased. The soil enzyme activities changed rapidly with N application in higher precipitation area but changed slowly in lower precipitation area. Soil microbial function diversity were increased with N application(4) N Fertilization could significantly increased DGGE bands of the soil nitrous acid bacteria and ammonium oxidation bacteria.and there were more bands with 2 years N fertilization than 1 year fertilization. Shannon index, evenness index and stability index of the soil nitrous acid bacteria and ammonium oxidation bacteria were increased with N application treatments. The biological community diversity of nitrifying bacteria were increased with N Fertilization.更多还原