缙云山森林土壤微生物数量与群落特征

Characteristics of microbial quantities and communities in forest soils of Jinyun Mountain

本文以重庆市缙云山国家森林保护区的毛竹林、马尾松针叶林、马尾松针阔混交林为供试对象,研究了不同森林群落的土壤微生物数量、群落特征及其与土壤养分的关系。结果表明,毛竹林土壤中的细菌、放线菌、真菌数量最多,混交林次之,针叶林最少,高低之间分别相差32.3倍(细菌)、19.2倍(放线菌)和19.3倍(真菌)。说明森林植被群落的生产力越高,枯枝落叶量越大,土壤微生物数量越多。在毛竹林土壤中,微生物的多样性指数、均匀度指数和优势度指数显著高于针叶林和混交林,说明毛竹土壤的生态环境相对稳定良好,微生物种群丰富,密度较大,种群优势突出。此外,土壤微生物存在明显的季节变化,夏季最高,冬季最低,与土壤有效氮、磷的季节变化基本耦合。土壤微生物数量与土壤有机质和碱解氮呈显著正相关(r有机质=0.592**～0.741**,r碱解氮=0.490*～0.581**,n=24);在毛竹林和混交林土壤中,土壤微生物数量与有效磷呈显著正相关(r毛竹林=0.461*,r混交林=0.450*,n=24),说明微生物在土壤有机质转化和氮、磷供应过程中起重要作用,与森林植被群落的生产力密切相关。

In present research work, Phyllostachys pubescen forest, coniferous forest of Pinus massoniana, and needle leaved forest of Pinus massoniana and Castanea mollissima were selected to study the relationships among microbial qualities, community characters and nutrients in soils. The results show that there are highest quantities of bacteria, actinomycetes and fungi in soils of P. pubescen forest and are followed by needle leaved forest and coniferous forest, and the quantities are varied in 32.3 （bacteria）, 19.2 （Actinomyces） and 19.3（Fungi）times among the forest colonies. Therefore, the higher the forest productivities and the litter return, the more the soil microbes. Compared to the coniferous forest and needle leaved forest, indexes of diversities, homogeneousness and dominance for microbial colonies are highest in P. pubescen forest soils, which suggests the stable and fine environment in P. pubescen forest soils with rich microbe groups and dominant species or strains. Moreover, microbes are changed seasonally in soils with the highest in summer and the lowest in winter, which are similar to the seasonable variations of available nitrogen and phosphorus in soils. There are positively correlations between microbes and soil organic matter （r=0.592＊＊–0.741＊＊, n=24） and NaOH hydrolyzed nitrogen （r=0.490＊–0.581＊＊＊, n=24） in all forest soils, and between microbes and available phosphorus in P. pubescen forest soils （r=0.461＊, n=24） and needle leaved forest soils （r=0.450＊, n=24）. Microbes could thus be important in the mineralization of organic matter and in supplies of available nitrogen and phosphorous in forest soils, which influence greatly the productivities of plant communities in forests.