湿地土壤微生物群落结构和功能对水分条件变化的响应

发布时间：2019-03-23 16:51

【摘要】：湿地生态系统具有独特的水文历史和生物特征,具有较高的生态多样性、物种多样性和生物生产力。而水文过程是影响湿地生态系统稳定和退化的关键因素,对湿地生态系统的物质循环和能量转化具有重要影响,而土壤微生物作为湿地生态系统的分解者,其群落结构和功能活性是如何响应水分变化的,我们知之甚少。本研究以鄱阳湖灰化苔草湿地表层土壤为研究材料,采用室内水分控制实验,模拟湿地水分条件,设置五种水分处理:自然干燥、湿润(含水量约30%)、淹水0cm、10cm和100cm。采用多种研究方法,对土壤理化因子、微生物生物量、细菌群落结构、胞外酶活性、碳源代谢活性进行分析。以期为湿地生态系统的保护与改善提供科学的理论依据。主要研究结果如下:(1)淹水条件能够显著提高土壤有机质和铵态氮含量,同时会升高土壤pH。土壤理化因子在处理的第72d达到了相对稳定的状态,同时研究发现除硝态氮含量外,土壤理化因子在不同淹水深度间无显著性差异。(2)湿润处理下的土壤微生物生物量最高,淹水处理次之,自然干燥处理最低,而不同的淹水深度间无显著差异。在不同的水分条件下,湿地土壤细菌群落结构在处理的前21d发生了剧烈变化呢,之后趋于稳定。同时研究还发现淹水环境中的土壤细菌群落结构显著不同于自然干燥和湿润处理。在对处理21d土壤微生物群落组成的研究中发现,自然干燥环境中含有较高丰度的细菌为Acidobacteriaceae_(Subgroup_1)和细球菌科(Micrococcaceae),湿润土壤环境中以草酸杆菌科(Oxalobacteraceae)和黄单胞杆菌科(Xanthomonadaceae)丰度最高;而淹水土壤中梭菌科(Clostridiaceae_1)的丰度相对较高。但淹水深度对细菌群落组成无显著影响。(3)土壤酶活性在处理的前21d未发生显著变化,之后分异变化明显。其中在自然干燥条件下土壤酶活性最低,湿润处理条件下的β-葡萄糖苷酶(Bglu)活性较高,而淹水条件下拥有较高的酚氧化酶(PERO)和过氧化物酶(PHOX)活性,但淹水深度对土壤酶活性无显著影响。选择自然干燥、湿润和淹水100cm三组水分条件处理的样品进行碳源利用测定分析,结果表明土壤碳源代谢能力在处理的前21d出现了显著的变化,之后趋于稳定。最终表现为,湿润处理的碳源代谢能力最强,淹水100cm次之,自然干燥处理最低。进一步研究发现在淹水条件下利用的主要碳源为氨基酸类。综上所述,湿润的土壤环境最有利于微生物生长代谢,淹水条件显著改变了土壤理化环境、细菌群落结构和组成,而干燥的土壤环境显著降低了土壤酶活性和碳源代谢能力。研究结果提示,维持大面积的洲滩湿地对湿地生态系统的保护至关重要,未来湿地保护不仅要关注湿地土壤的淹水深度,更要关注湿地的淹水面积和淹水时长。
[Abstract]:Wetland ecosystem has unique hydrological history and biological characteristics, with high ecological diversity, species diversity and biological productivity. Hydrological process is the key factor that affects the stability and degradation of wetland ecosystem, and it has an important influence on the material cycle and energy transformation of wetland ecosystem, and soil microorganism is the decomposer of wetland ecosystem. We know little about how the community structure and functional activities respond to water changes. In this study, the surface soil of Poyang Lake ash Carex marsh was used as the research material. The indoor water control experiment was used to simulate the moisture condition of the wetland. Five kinds of water treatments were set up: natural drying, wetting (about 30% water content), flooding 0 cm, 10 cm and 100 cm. Soil physical and chemical factors, microbial biomass, bacterial community structure, extracellular enzyme activity and carbon source metabolic activity were analyzed by various methods. In order to provide scientific theoretical basis for the protection and improvement of wetland ecosystem. The main results are as follows: (1) the content of soil organic matter and ammonium nitrogen can be significantly increased by flooding conditions, and the soil pH. will be increased at the same time. The soil physical and chemical factors reached a relatively stable state at 72 days after treatment, and it was found that except for nitrate nitrogen content, There was no significant difference in soil physical and chemical factors among different flooding depths. (2) the soil microbial biomass was the highest in wet treatment, followed by flooding treatment, and the lowest in natural drying treatment, while there was no significant difference among different flooding depths. Under different water conditions, the bacterial community structure of wetland soil changed dramatically in the first 21 days, and then stabilized. At the same time, it was found that the community structure of soil bacteria in flooded environment was significantly different from that of natural drying and wetting treatment. In the study of soil microbial community composition for 21 days, it was found that Acidobacteriaceae_ (Subgroup_1) and (Micrococcaceae), were the most abundant bacteria in natural dry environment. In the moist soil environment, the highest abundance of (Oxalobacteraceae) and Xanthomonas were found in the two families. The abundance of Clostridiaceae_1 was relatively high in flooded soil. However, the depth of flooding had no significant effect on the composition of bacterial community. (3) there was no significant change in soil enzyme activity in the first 21 days of treatment, but the variation of soil enzyme activity was obvious in the first 21 days of treatment. Under the condition of natural drying, the activity of soil enzyme was the lowest, the activity of 尾-glucosidase (Bglu) was higher under the condition of wet treatment, but the activity of phenoloxidase (PERO) and peroxidase (PHOX) was higher under the condition of flooding. However, the depth of flooding had no significant effect on soil enzyme activity. Carbon source utilization analysis of the samples treated with natural drying, wetting and flooded 100cm showed that the metabolic capacity of soil carbon sources changed significantly in the first 21 days after treatment, and then tended to be stable. Finally, the ability of carbon metabolism was the strongest in wet treatment, followed by flooded 100cm, and the lowest in natural drying treatment. Further study found that the main carbon source used under flooded condition was amino acid. In conclusion, moist soil environment is the most favorable for microbial growth and metabolism, flooding condition significantly changed soil physical and chemical environment, bacterial community structure and composition, while dry soil environment significantly decreased soil enzyme activity and carbon source metabolism ability. The results suggest that maintaining a large area of Zhoutan wetland is very important to the protection of wetland ecosystem. In the future wetland protection should not only pay attention to the flooding depth of wetland soil, but also pay attention to the flooded area and duration of wetland flooding.
【学位授予单位】：南昌大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S154.3

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