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通过在亚热带滨海防护林湿地松、尾巨桉、纹荚相思和木麻黄人工林中设置去除凋落物、去除根系和对照处理,分析改变地上、地下碳输入对沙地人工林土壤微生物生物量、群落结构和功能的影响.2015年9月,在处理设置一年后采集各处理样方0~10 cm土壤样品,分别采用磷脂脂肪酸分析方法和微孔板酶检测技术对土壤样品的微生物群落组成和6种酶活性进行测定.结果表明:碳输入处理对土壤微生物生物量的影响因树种而异,并主要取决于凋落物和根系的质量.在尾巨桉林中,去除根系使得脂肪酸总量、革兰氏阳性细菌、革兰氏阴性细菌、真菌和放线菌生物量分别显著减少了31%、30%、32%、36%和26%,去除凋落物使得革兰氏阳性细菌、真菌和放线菌生物量显著减少了24%、27%和24%,而其他树种处理对微生物生物量无显著影响.碳输入处理对土壤微生物群落结构的影响主要表现为真菌丰度下降而放线菌丰度上升.不同树种的土壤酶活性对处理的响应表现不一致:湿地松、纹荚相思和木麻黄林分去除凋落物显著降低土壤中纤维素水解酶、β-葡萄糖苷酶、酸性磷酸酶和乙酰氨基葡萄糖苷酶活性,去除根系仅分别降低和提高了湿地松和纹荚相思林β-葡萄糖苷酶的活性;湿地松、木麻黄人工林去除凋落物显著降低了多酚氧化酶和过氧化物酶活性;去除根系对所有树种土壤氧化酶活性影响不显著.不同树种的凋落物、根系特性是影响土壤微生物群落组成和酶活性的重要因子,碳输入处理造成的土壤温度、水分等微环境的改变也是土壤微生物性质变化的重要驱动力.
By removing litter, removing roots and controlling treatments in the Pinus elliottii Eucalyptus, Eucalyptus urophylla, Acacia crassicarpa and Casuarina equisetifolia plantations in the subtropical coastal shelterbelts, we analyzed the effects of aboveground and underground carbon inputs on soil microbial biomass, Structure and function of soil samples collected in September 2015. After one year of treatment, soil samples from 0-10 cm soil samples were collected and analyzed by phospholipid fatty acid assay and microplate enzyme assay respectively for microbial community composition and soil microbial biomass The results showed that the effects of carbon input on soil microbial biomass varied with tree species and mainly depended on the quality of litter and root system.In the Eucalyptus camaldulensis forest, Gram-positive bacteria, Gram-negative bacteria, fungi and actinomycetes biomass were significantly reduced by 31%, 30%, 32%, 36% and 26% respectively. Removal of litter made Gram-positive bacteria, fungi and The biomass of actinomycetes was significantly reduced by 24%, 27% and 24%, while the treatments of other tree species had no significant effect on microbial biomass. The effects of carbon input treatment on soil microbial community structure were mainly manifested The abundance of fungi decreased and the abundance of actinomycetes increased.The activities of soil enzymes in different species showed inconsistent response to treatment: Pinus elliottii, Acacia confusa and Casuarina equisetifolia litter removal significantly decreased the activities of cellulose hydrolase, β - glucosidase, acid phosphatase and acetamidoglucosidase activity, removal of the root system only to reduce and improve the Pinus elliottii and P. acuminatum beta-glucosidase activity; wetland Pinus elliotii plantation to remove litter significantly And decreased the activity of polyphenol oxidase and peroxidase.The effect of root removal on soil oxidase activity was insignificant in all tree species.Litter characteristics and root system of different tree species were the important factors affecting soil microbial community composition and enzyme activity.The carbon input treatment The change of microenvironment such as soil temperature and moisture is also an important driving force for the change of soil microbial properties.