镜泊湖岩溶台地不同植被类型土壤微生物群落特征

为了探讨不同演替阶段植被类型土壤微生物群落特征,分别选取镜泊湖岩溶台地草本、矮灌木、高灌木、小乔木与灌木混生(简称混生)群落、落叶阔叶林及针阔混交林6种典型植被类型,进行植物群落调查和对土壤微生物生物量、群落结构和多样性指标、土壤物理化学性质的测定。结果表明：从土壤微生物量、土壤微生物群落组成、土壤微生物代谢动力学过程和代谢功能多样性的角度来看,各种植被类型土壤微生物群落具有明显的差异。演替前期的草本群落土壤微生物量碳氮、细菌生物量、真菌生物量,代谢活性及丰富度指数均最低,但Shannon-Wiener多样性指数和均匀度指数显著(P<0.05)高于其他植被类型。矮灌木土壤微生物群落组成显著受植被类型的影响。高灌木群落和混生(小乔木与灌木混生)群落具有极强的相似性, 但在碳源利用类型上两者表现出一定的差异。落叶阔叶林代谢活性最高,碳源利用能力最强,能利用BIOLOG微孔板中的所有31种碳源,这与其具有较高的微生物量碳氮和细菌生物量一致,其代谢功能丰富度最高。演替后期的针阔混交林下的土壤pH最低,真菌比例升高,在碳源丰富的条件下具有极强的竞争优势(仅次于落叶阔叶林),但在碳源贫瘠的条件下其利用碳源能力较弱(仅高于草本)。植被可能主要通过土壤全磷和有机质影响土壤微生物代谢功能多样性。

Soil microbial community characteristics under different vegetation types at the Holocene-basalt Platform, Jingpo Lake area, Northeast China

To investigate the soil microbial characteristics under different successional stages at the Holocene-Basalt Platform, Jingpo Lake area, Northeast China, we carried out the research under six typical vegetation types, i.e. herbs, dwarf shrubs, highbush, shrubs mixed with small trees, deciduous broadleaf and conifer mixed with broadleaf. We conducted plant community survey, and measured soil physiochemical properties, soil microbial biomass, community-level substrate utilization characteristics (BIOLOG EcoPlates^TM) and microbial community structure (Phospholipid Fatty Acid Profiles PLFA). Significant differences existed among vegetation types. Under herb soil (in the early stage of succession), microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), bacterial biomass, fungal biomass, metabolic activity (Average Well Color Development,AWCD) and the richness index were the lowest, while the Shannon-Wiener Diversity index was significantly (P<0.05) higher than other vegetation types. The structure of soil microbial community was influenced by dwarf shrub. Dwarf shrub soil had the highest actinomycete biomass (34.2 nmol/g), which might be relevant to the dominant leguminous shrub species, Lespedeza daurica. Highbush soil and shrub mixed with small tree soil were similar in microbial biomass, PLFA composition, metabolic activity, functional diversity indexes, and slight difference existed in types of carbon sources utilized. Deciduous and broadleaf soil had the highest metabolic activity, richness index and ability of carbon utilization, which was in accordance with its high total microbial biomass and bacterial biomass. At the final stage of succession, fungal biomass of conifer mixed with broadleaf soil increased, and soil pH was the lowest. Vegetation might mediate soil microbial functional diversity by effecting soil phosphorous and soil organic carbon in our study. However, there were no significant (P>0.05) relationship between herb layer diversity and soil microbial functional diversity, and further studies were needed to recover the complex interactions between herb layer and soil microbial functional diversity.