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海南不同林龄木麻黄海防林土壤微生物群落组成与酶活性的动态分析
徐志霞, 李小容, 蔡莲子,等
热带岛屿生态学教育部重点实验室,海南师范大学 生命科学学院
摘要:
【目的】研究海南滨海木麻黄林地土壤微生物群落组成和酶活性随林龄的变化规律,探讨木麻黄成熟林林地地力衰退的原因。【方法】在位于海南省海口市海滨的木麻黄幼龄林(5年生)、中龄林(15年生)和成熟林(30年生)中各设置3个10 m×10 m的样方,采用“S”形5点混合取样法取5~20 cm土层土样,提取土壤宏基因组DNA对土壤细菌、真菌的菌属组成、相对丰度和多样性进行分析,测定土壤酶活性并对酶活性与土壤理化性质的关系进行通径分析,同时对土壤微生物与土壤酶活性和理化性质的关系进行典范对应分析(CCA)。【结果】(1)中龄林土壤细菌和真菌群落的物种组成最丰富且均匀程度高。各林龄林地土壤细菌均以酸杆菌_Gp1占优势,中龄林土壤中特有菌属鞘氨醇杆菌属也为优势菌属。各林龄土壤真菌以发菌科中一种尚未分类的菌属占优势,其在成熟林中相对丰度最高。(2)随林龄增加,土壤蔗糖酶和脲酶活性逐渐升高,而过氧化氢酶、过氧化物酶活性逐渐降低,多酚氧化酶和酸性磷酸酶活性呈先降低后升高的趋势。通径分析表明,土壤呼吸作用、pH值及全钾、全磷、有机质含量是影响土壤酶活性的直接因素。(3)CCA分析表明,铵态氮对细菌群落的影响程度最大,而土壤体积质量对真菌群落的影响程度最大。多酚氧化酶活性与分枝杆菌属相关性最大,而酸性磷酸酶、过氧化物酶、过氧化氢酶活性与土壤真菌相关菌属相关性最大。土壤优势菌属中鞘氨醇杆菌属与有机质、硝态氮含量最相关,发菌科中一种尚未分类的真菌与过氧化氢酶活性、pH最相关。【结论】成熟林中微生物群落丰富度和均匀程度降低以及氧化还原酶类活性随林龄增长而逐渐降低,是木麻黄成熟林林地地力衰退的一个重要原因。
关键词:  木麻黄  微生物  土壤酶活性  理化性质
DOI:
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基金项目:国家自然科学基金项目(31260068);海南省自然科学基金(2018CXTD337)
Analysis of soil microbial community and enzyme activity of Casuarina equisetifolia plantations at different stand ages in Hainan
XU Zhixia, LI Xiaorong, CAI Lianzi,et al
Abstract:
【Objective】This paper studied soil microbial community composition and soil enzyme activity of Casurina equisetifolia at different stages to explore the cause of soil degradation in C.equisetifolia mature plantation.【Method】C.equisetifolia plantations in the coast of Haikou,Hainan were selected and three 10 m×10 m sample plots were created in the stands at young stage (5-year),middle aged stage (15-year) and mature stage (30-year).The S shape five point sampling method was used for stratification and sampling of soil (5-20 cm).Metagenomic DNA was extracted for analyzing composition at genus level,relative abundance and diversity of the bacteria and fungi communities.The soil enzyme activities were also measured.Path analysis between soil enzyme activities and nutrients,as well as canonical correspondence analysis (CCA) of soil microbe,enzyme activities and soil physico chemical properties were carried out.【Result】(1) Richness and evenness of microbial communities were the highest in middle-aged forest.The population density of Acidobacteria_Gp1 was the greatest in the bacterial community at all ages.In the middle-aged forest,Sphingobacterium took advantage in the bacterial community.An unclassified Trichocomaceae was predominant in the fungal community,and its abundance was the highest in the mature forest.(2) The activities of urease and invertase increased as the growth of plantation,while the activities of catalase and peroxidase decreased.The polyphenol oxidase and acid phosphatase activities decreased from young stage to middle-aged stage,and then increased.Soil respiration,pH,total K,organic matter,and total P were crucial factors affecting enzyme activities.(3) Ammonia N was the largest factor on the bacterial community CCA ordination,and the soil bulk density impacted fungal community the most.Polyphenol oxidase activity showed good correlation to Mycobacterium,and same correlation was found between soil fungi and acid phosphatase,catalase,peroxidase.Sphingobacterium showed good correlations with organic matter and nitrate N.The unclassified trichocomaceae was related to soil catalase and pH.【Conclusion】Decrease of evenness of microbial communities and oxidoreductase activity with the growth of plantation was the one of the main reasons for plantation degradation.
Key words:  Casuarina equisetifolia  microorganisms  soil enzyme activity  physicochemical properties