贵州高原草海湿地退化对土壤有机碳及酶活性分布的影响

发布时间：2019-03-12 19:31

【摘要】：全球变暖是全球面临的重大环境问题。湿地由于碳的产生超过了碳的分解成为一个重要的碳库,在全球碳平衡中具有重要的作用。湿地生态系统中土壤碳库的微小变化都可能对大气CO2浓度产生重大影响。由于人类活动和气候变化的影响,湿地生态系统退化问题日益加剧。湿地退化可能会导致土壤碳“源”“汇”功能转化,并产生显著的生态环境效应。本研究以贵州草海湿地为研究对象,通过2015年和2016年两年的野外监测和实验室分析,对草海湿地不同退化阶段土壤有机碳及其活性组分和土壤胞外酶活性的时空分布特征进行了研究,找出了影响湿地土壤有机碳和胞外酶活性分布的生态因子,探讨了土壤酚类物质、有机碳及酶活性的关系。主要研究结果如下:(1)草海湿地可分为四个退化阶段分别为,深水区、浅水区、沼泽区和草甸区。湿地退化导致土壤有机碳库大幅降低,在2015年表层有机碳含量平均值从243.03 g/kg降至37.35 g/kg,在2016年平均值从231.64 g/kg降至19.28 g/kg,草甸区湿地土壤有机碳略高于沼泽区,沼泽区干湿交替的土壤条件不利于土壤有机碳的储存。不同退化阶段土壤有机碳及其活性组分剖面分布不尽相同。草海湿地土壤可溶性有机碳(DOC)和易氧化有机碳(EOC)含量随湿地退化大幅下降,2016年0-10 cm土壤可溶性有机碳平均值从深水区99.90 mg/kg降至草甸区20.36 mg/kg,易氧化有机碳平均值从深水区80.17 g/kg降至草甸区5.82 g/kg。EOC/SOC比例较大,但DOC/SOC对湿地退化更为敏感。草海湿地土壤有机碳及其活性组分密切相关,且受含水率、pH等理化因子的变化影响。(2)草海湿地土壤多酚氧化酶活性随湿地退化逐渐升高,具有明显的季节性变化,在2016年多酚氧化酶活性由1.12 mg/d/g升至8.76mg/d/g,水解酶活性无明显的季节性变化规律。草海湿地湿地酶活性与土壤p H、含水率及营养元素等理化因子密切相关,土壤多酚氧化酶与水解酶活性的相关关系不显著。(3)草海湿地土壤酚类物质含量随湿地退化大幅减少,从10.96g/kg降至0.62 g/kg。不同退化阶段土壤酚类物质剖面分布不尽相同,深水区和浅水区植被影响剖面分布。草海湿地土壤有机碳与土壤酚类物质呈极显著正相关关系(P0.01)。土壤有机碳、酚类物质均与土壤氧化酶呈极显著负相关关系(P0.01)。土壤有机碳、酚类物质均与土壤蔗糖酶、碱性磷酸酶活性呈极显著正相关关系(P0.01)。土壤干旱复氧,多酚氧化酶活性增强,酚类物质含量减少,但水解酶活性并未随湿地退化提高,与土壤碳储存的“酶锁”机制不完全相符。
[Abstract]:Global warming is a major environmental problem facing the world. Wetland becomes an important carbon pool because the carbon production exceeds the decomposition of carbon and plays an important role in the global carbon balance. The small changes of soil carbon pool in wetland ecosystem may have a significant impact on atmospheric CO2 concentration. Due to the impact of human activities and climate change, wetland ecosystem degradation is becoming more and more serious. Wetland degradation may lead to the transformation of "source" and "sink" function of soil carbon and produce significant ecological and environmental effects. In this study, Guizhou Caohai Wetland was studied through field monitoring and laboratory analysis in 2015 and 2016. The temporal and spatial distribution characteristics of soil organic carbon and its active components and soil extracellular enzyme activity in different degradation stages of Caohai wetland were studied, and the ecological factors affecting the distribution of soil organic carbon and extracellular enzyme activity were found out. The relationship among phenol, organic carbon and enzyme activity in soil was discussed. The main results are as follows: (1) Caohai wetland can be divided into four degradation stages, namely, deep water area, shallow water area, swamp area and meadow area. Wetland degradation has led to a significant decrease in the soil organic carbon pool, from an average of 243.03 g/kg to 37.35 g / kg in 2015 and from 231.64 g/kg to 19.28 g / kg in 2016. The soil organic carbon was slightly higher in the meadow area than in the swamp area, and the soil conditions of dry-wet alternation in the swamp area were not conducive to the storage of soil organic carbon. The profile distribution of soil organic carbon and its active components was different in different degradation stages. The contents of soluble organic carbon (DOC) and oxidizable organic carbon (EOC) in soil of Caohai wetland decreased significantly with the degradation of wetland. The average content of soluble organic carbon in soil of 0 / 10 cm decreased from 99.90 mg/kg in deep water area to 20.36 mg/kg, in meadow area in 2016. The average oxidizable organic carbon decreased from 80.17 g/kg in deep water to 5.82 g/kg.EOC/SOC in meadow, but DOC/SOC was more sensitive to wetland degradation. Caohai wetland soil organic carbon and its active components are closely related, and affected by the changes of water content, pH and other physical and chemical factors. (2) the soil polyphenol oxidase activity of Caohai wetland increased gradually with wetland degradation, and had obvious seasonal changes. In 2016, the activity of polyphenol oxidase increased from 1.12 mg/d/g to 8.76 mg / kg, and the activity of hydrolase had no obvious seasonal variation. The enzyme activity was closely related to the soil pH, water content and nutrient elements, and the enzyme activity was closely related to the soil pH, water content and nutrient elements. The relationship between soil polyphenol oxidase and hydrolase activity was not significant. (3) with the degradation of wetland, the content of phenol in soil decreased greatly, from 10.96g/kg to 0.62g / kg 路kg ~ (- 1). The distribution of phenolics in different degradation stages is different, and the distribution of vegetation in deep and shallow water areas is different. There was a significant positive correlation between soil organic carbon and phenolics in Caohai wetland (P0.01). Soil organic carbon and phenol were negatively correlated with soil oxidase (P0.01). Soil organic carbon and phenols were positively correlated with soil invertase and alkaline phosphatase activities (P0.01). Under drought and reoxygenation, the polyphenol oxidase activity increased and the phenol content decreased, but the hydrolase activity did not increase with the degradation of wetland, which was not consistent with the "enzyme locking" mechanism of soil carbon storage.
【学位授予单位】：贵州师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S153.6;S154.2

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