马尾松×红锥异龄混交林对土壤微生物群落结构和功能的影响

Effects of Uneven-aged Pinus massoniana×Castanopsis hystrix Mixed Plantations on Structural and Functions of Soil Microbial Community

关键词:  马尾松  红锥  异龄混交林  土壤微生物群落  土壤酶活性

Key words:  Pinus massoniana  Castanopsis hystrix  uneven aged mixed plantations  soil microbial community  soil enzyme activity

摘要:

探讨马尾松（Pinus massoniana）纯林改造成马尾松×红锥（Castanopsis hystrix）异龄混交林对土壤微生物群落结构和功能的长期生态效应，为马尾松人工林质量的精准提升提供理论依据。以60 a生的马尾松纯林和改造后的异龄混交林为对象，比较分析纯林和异龄混交林土壤微生物群落结构和功能差异，以及土壤微生物类群与土壤酶活性和土壤性质的相关性。两种林分土壤磷脂脂肪酸（PLFAs）含量均大于0.01 nmol·g^-1的标记种类为27种，其中25种PLFAs标记含量均为纯林高于异龄混交林；马尾松纯林土壤微生物群落、细菌、真菌、放线菌、丛枝菌根真菌、革兰氏阳性菌、革兰氏阴性菌的PLFAs均显著或极显著高于异龄混交林；马尾松纯林土壤微生物群落的PLFAs多样性均高于异龄混交林，其中土壤PLFAs丰富度和均匀度指数差异不显著，而香农威纳指数、Simpson指数差异显著；马尾松纯林改造为异龄混交林后，土壤β-1，4-葡萄糖苷酶、N-乙酰-β-氨基葡萄糖苷酶、酚氧化酶、过氧化物酶活性均呈现不同程度的降低，而土壤酸性磷酸酶和脲酶活性增加；相关分析表明，不同土壤微生物类群均与β-1，4-葡萄糖苷酶、N-乙酰-β-氨基葡萄糖苷酶、酚氧化酶、过氧化物酶呈正相关，与酸性磷酸酶和脲酶呈负相关；与土壤有机质、有效钾呈极显著正相关，而与土壤含水量、土壤微生物生物量氮呈显著负相关。马尾松×红锥异龄混交林对土壤微生物群落结构和功能的长期生态效应不明显，异龄混交林结构简单，物种多样性少，土壤有机质低，以及雨季土壤含水量过高是其土壤微生物群落多样性和土壤酶活性低于纯林的主要原因。

Abstract:

The objective of this study was to analyze the long-term ecological effects of the conversation of pure Pinus massoniana plantations to P.massoniana and Castanopsis hystrix uneven aged mixed plantations on soil microbial community structure and function and provide theoretical basis for the accurate improvement of the quality of P.massoniana plantation. Based on the 60-year-old pure P.massoniana forest and P.massoniana and C.hystrix uneven aged mixed plantations, the differences of soil microbial community structure and function between pure and uneven-aged forests and the correlation between soil microbial groups and soil enzyme activities and soil properties were compared. Our results showed that there were 27 kinds of labeled PLFAs in the two plantations with more than 0.01 nmol·g^-1, among which, the content of 25 PLFAs markers was higher in pure plantations than that in mixed plantations. The PLFAs of soil microbial community, bacteria, fungi, actinomycetes, arbuscular mycorrhizal fungi, Gram-positive bacteria and Gram-negative bacteria in pure plantations were significantly higher than that in the mixed plantations. The PLFAs diversity of the soil microbial communities in pure P.massoniana plantations was higher than that of the mixed plantations. Among them, the difference of soil PLFAs richness and evenness index was not significant, while the Shannon Wiener index and Simpson index were significantly different. After the conversion of P.massoniana plantations to uneven aged mixed plantations, soil β-1, 4-glucosidase, N-acetyl-β-glucosaminidase,phenol oxidase and peroxidase showed different degrees of decrease, while soil acid phosphatase and urease activity increased. Correlation analysis showed that soil microbial community was positively correlated with β-1,4-glucosidase,N-acetyl-β-glucosaminidase,phenol oxidase, peroxidase, negatively correlated with acid phosphatase and urease, positively correlated with soil organic matter, available potassium, and negatively correlated with soil water content, microbial biomass nitrogen. The long-term ecological effects of P.massoniana and C.hystrix uneven aged mixed plantations on soil microbial community structure and function were not obvious. The simple structure of uneven aged mixed plantations, less species diversity, low soil organic matter, and high soil water content in the rainy season are the main reasons for its soil microbial community diversity and soil enzyme activity being lower than pure forest.