两种土壤中梭梭冠下土壤微生物群落的空间变异研究

发布时间：2018-03-06 18:32

本文选题：荒漠土壤　切入点：梭梭　出处：《新疆大学》2016年博士论文　论文类型：学位论文

【摘要】：在干旱区和半干旱区生态系统中,灌木“肥岛”对植被的生产力、分布格局以及生态系统过程具有重要影响。土壤微生物在凋落物分解、养分循环中起着重要作用,是灌木“肥岛”形成和发育的重要贡献者。在微生物群落组成中,不同类别的土壤微生物对水分和养分变异的敏感性或忍耐性各不相同,其空间变异受“肥岛”(水分、养分)的强烈影响,有必要关注“肥岛”中土壤微生物群落的空间变异。对于干旱区的荒漠生态系统而言,研究土壤微生物群落的空间变异对于养分平衡、植物生长、系统的稳定与可持续性具有非常重要的意义。梭梭是亚欧大陆干旱区荒漠生态系统的优势种之一。在新疆,梭梭主要分布于准噶尔盆地的沙漠—绿洲交错区,其生物量占群落总生物量的90%以上,对维持生态系统生产力具有极其重要的作用。风沙土和灰漠土是梭梭分布区的主要土壤类型。从土壤系统分类学划分标准来看,风沙土为干旱性砂质新成土(Torripsamments),灰漠土为钙化正常性干旱土(Haplocalcids)。两种土壤的机械组成迥异,风沙土的质地较粗,砂粒含量为灰漠土的2.0-2.3倍;而灰漠土的质地较细,粉粒和黏粒含量分别为风沙土的3.1-3.5倍、2.8-5.2倍。由于极端干旱的环境条件,两种土壤共同的特征是养分贫瘠,其如何维持养分循环与平衡,决定了荒漠植物的生长与分布。从已有研究来看,多数与“肥岛”相关的研究集中于养分和水分,虽然很多研究强调了土壤微生物群落的作用,但是以土壤微生物群落为研究对象,基于“肥岛”的实验研究相对较少。本研究选取了研究区域两种代表性土壤,基于梭梭“肥岛”,探讨了土壤微生物群落(生物量、多样性和结构组成)的空间变异特征及其与水分、养分、根系的关系。研究目标是检验土壤类型是否对冠下土壤微生物群落的空间变异具有调节作用。本研究的结果表明:(1)两种土壤中均存在“肥岛”现象,水分和养分含量从主根向外随距离增加而降低,且随深度增加而降低。在表层土壤(0-20 cm)中,与灰漠土相比,风沙土的水分、有机质、有效氮和有效磷的富集率分别是灰漠土的4.7-11.9倍、3.5-8.7倍、3.1-4.8倍、2.2-2.7倍。两种土壤中细根的生物量密度、表面积密度、根长密度从主根向外不断减小;与灰漠土相比,风沙土“肥岛”中细根无论在水平方向上还是在垂直方向上都分布更广。整体而言,风沙土中“肥岛”发育的范围与强度更大。(2)从主根向外土壤微生物生物量和多样性随水分、养分、细根密度的变异数据表明,在漠生态系统中,土壤微生物生倾向于在水分和养分资源丰富的肥岛中繁荣,形成了不连续分布的斑块状分布格局。与灰漠土相比,风沙土中的微生物生物量和多样性空间变异较强,表明土壤类型可能决定了冠下土壤微生物生物量和多样性空间变异的强弱程度。(3)在风沙土中,细菌、真菌生物量从主根附近(距主根5 cm)到株间空地(距主根200 cm)分别减少了50.3-53.7%、74.7-84.1%,差异显著;而在灰漠土中,细菌、真菌生物量从主根向外的变异没有显著差异。这表明土壤类型对不同类别微生物生物量的空间变异具有调控作用,且与其自身对水分和养分变异的敏感性和忍耐性有关。(4)风沙土中革兰氏阳性菌、革兰氏阴性菌的生物量从主根附近到株间空地分别减少了50.8-80.5%、92.6-98.0%,灰漠土中分别减少了14.7-65.6%、63.1-85.3%,差异较显著,且风沙土中革兰氏阳性菌和革兰氏阴性菌生物量的空间变异强于灰漠土,进一步表明土壤类型对不同类别细菌生物量的空间变异具有调控作用,且与其自身对水分和养分变异的敏感性和忍耐性有关。
[Abstract]:In the ecosystem of arid and semi-arid areas, the shrub "fertile island" on vegetation productivity, has an important influence on the distribution pattern and ecosystem processes. Soil microbes in litter decomposition, plays an important role in nutrient cycling, is a shrub "fertile island" form an important contribution and development. In the microbial community composition in different types of soil moisture and nutrient variation in sensitivity or tolerance is different, the spatial variability of the "fertile island" (moisture, nutrients) strongly influence, it is necessary to focus on "the spatial variability of soil microbial communities in the fertile islands. For desert ecosystem in arid area, spatial variability study on Soil microbial community for nutrient balance, plant growth, has a very important significance to the stability and sustainability of the system. Ammodendron is one of dominant Eurasian arid area, ecological system In Xinjiang, the desert oasis ecotone of Haloxylon ammodendron is mainly distributed in Junggar basin, the biomass accounted for more than 90% of the total biomass, has a very important role in maintaining ecosystem productivity. Sandy soil and grey desert soil is the main soil type distribution. Haloxylon from standard classification system of soil, sand the soil dry sandy loam (Torripsamments), grey desert soil drought soil as normal calcification (Haplocalcids). Two kinds of different mechanical composition of soil, sandy soil texture coarse sand content is 2.0-2.3 times of the grey desert soil; and gray desert soil texture is fine silt and clay. Were 3.1-3.5 times, 2.8-5.2 times. Sandy soil due to the extreme drought conditions, two kinds of common characteristics are soil nutrient poor, how to maintain the nutrient cycling and balance, determines the growth and distribution of desert plants from the existing research. Look, most of the related research and the "fertile island" focused on nutrients and moisture, although many studies emphasize the role of soil microbial communities, but the soil microbial community as the research object, based on the "fertile island" experimental researches. This study selected two representative research area soil, Haloxylon "fertile island based on the study of soil microbial community (composition of biomass, diversity and structure) of the spatial variability and moisture, nutrients, root relationship. The goal of this research is to test whether the soil type has a moderating effect on the spatial variability of soil microbial community under the crown. The results of this study show that: (1) two in the soil there were" fertile island "phenomenon, water and nutrient content from the root outward with the increase of the distance decreased, and decreased with depth. In the surface soil layer (0-20 cm), compared with the grey desert soil, sandy soil moisture, The enrichment rate of organic matter, available nitrogen and available phosphorus were 4.7-11.9 times, the grey desert soil 3.5-8.7 times, 3.1-4.8 times, 2.2-2.7 times. The two kinds of soil fine root biomass density, surface area density, root length density decreases from the root outward; compared with the grey desert soil, sandy soil "fertile island" the fine root both in the horizontal direction or in vertical direction are more widely distributed. Overall, the scope and intensity of aeolian sandy soil in the "fertile island" development more. (2) from the root to soil microbial biomass and diversity with moisture, nutrients, variation of root density data show that in the desert ecosystem in the soil microorganisms tend to thrive in water and nutrient rich fertile island, the formation of plaque distribution pattern of discontinuous distribution. Compared with the grey desert soil, the variation of microbial biomass in sandy soil and strong spatial diversity, indicating that the soil type may never The degree of variation of soil microbial biomass under canopy and spatial diversity. (3) bacteria in sandy soils, and fungal biomass from the root (near 5 cm from the root to the empty space between lines) (from the root 200 cm) were reduced by 50.3-53.7%, 74.7-84.1%, the difference was significant; while in grey desert soil in bacteria, there was no significant difference between the variation of fungal biomass from root outward. This shows the spatial variability of different types of microbial biomass in soil type has its own regulation, and on water and nutrient variation in sensitivity and tolerance. (4) of gram positive bacteria in sandy soil, the biomass of gram negative bacteria. From the root to the empty space between near strains were reduced by 50.8-80.5%, 92.6-98.0%, gray desert soil were reduced by 14.7-65.6%, 63.1-85.3%, significantly, and the variation of aeolian sandy soil in gram positive and gram negative bacteria biomass of strong space In grey desert soil, it is further indicated that soil types play a regulatory role in the spatial variation of bacterial biomass of different categories, and are related to their sensitivity and tolerance to water and nutrient variation.

【学位授予单位】：新疆大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：S714.3

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