长白山温带森林不同演替阶段土壤化学性质及微生物群落结构的变化

Soil chemical properties and microbial community structure at different succession stages of temperate forest in Changbai Mountains

土壤微生物是生态系统物质循环和能量流动的驱动者,其群落结构可以用来表征土壤生态过程及其对地上植被变化的响应机制。本研究采用时空替代法在长白山地区选取了阔叶红松林演替序列的5个不同阶段:杨桦幼龄林、杨桦中龄林、杨桦成熟林、阔叶红松成熟林和阔叶红松过熟林,采用磷脂脂肪酸法(PLFA)测定了土壤微生物群落组成和结构,分析了其随地上植被演替过程的变化,同时比较了不同演替阶段土壤化学性质差异。结果表明:随着演替的正向进行,土壤总有机碳、全碳、全氮、全磷含量显著提高,碳氮比逐渐下降。土壤微生物生物量、群落结构及组成发生明显变化:土壤微生物总PLFAs、细菌PLFAs、革兰氏阳性菌PLFAs、革兰氏阴性菌PLFAs含量显著增加;真菌PLFAs(18:2ω6c)先增加后减少,中期阶段的杨桦成熟林土壤真菌PLFA含量最高,同时细菌/真菌最小;革兰氏阳性菌/革兰氏阴性菌(G+/G-)随着演替的进行逐渐增大。土壤微生物生物量与土壤全碳、总有机碳、全氮、全磷含量呈显著正相关,与碳氮比呈显著负相关;冗余分析(RDA)结果显示,全碳、总有机碳、全氮和碳氮比是影响土壤微生物群落结构的主要因素。本研究表明,随着植被演替的正向进行,土壤质量逐渐提高;土壤微生物群落组成明显改变;土壤微生物群落结构与土壤理化性质显著相关。

As a major driver in nutrient cycling and energy flowing of terrestrial ecosystem,soil microorganisms are sensitive to the change of soil chemical property. In this study,by a temporalspatial substitution method,a secondary successional chronosequence of five different stages（ young broadleaved forest,mid-aged broadleaved forest,mature broadleaved forest,mature broadleaved Korean pine mixed forest,and old broadleaved Korean pine mixed forest） in Changbai Mountains was chosen to compare the soil chemical properties and microbial community structure by phospholipid fatty acid（ PLFA）. The result indicted that soil organic carbon（ SOC）,total nitrogen（ TN） and total phosphorus（ TP） contents increased over succession while the C / N ratio decreased gradually. Soil microbial biomass,microbial community structure and composition changed with the forest succession. The total PLFAs,bacterial PLFAs,Gram-positive bacterial PLFAs,Gram-negative bacterial PLFAs and Gram-positive Bact PLFA / Gram-negative Bact PLFA（ G＋/G-） increased significantly,while the fungal PLFAs increased firstly and decreased lately.At the middle stage of the succession（ mature broadleaved forest）,the quantity of PLFA18： 2ω6c（ an indicator of fungal biomass） was highest while the ratio of Fung PLFA / Bact PLFA was lowest. Correlation analysis showed that the microbial biomass was positively correlated with total carbon（ TC）,SOC,TN,TP contents and negatively correlated with C / N ratio. Redundancy analysis（ RDA） indicated that TC,TN,SOC and C / N ratio were the main factors influencing microbial community structure.