滨海沙地3种人工林表层土壤微生物量及其影响因素

为探究福建东南沿海不同人工林砂质土壤微生物生物量碳(MBC)和生物量氮(MBN)及其影响因子,以肯氏相思(Acaica cunninghamia)、纹荚相思(Acacia aulacocarpa)和木麻黄(Casuarina equisetifolia)人工林为对象,采用通径分析模型,分析土壤微生物量对土壤理化性质、凋落物和细根生物量的响应。结果显示:3种人工林土壤MBC和MBN质量分数分别为42.60~51.56和5.38~6.88 mg·kg~(-1),且木麻黄的MBC和MBN质量分数均显著高于纹荚相思和肯氏相思(P0.05)。土壤w(MBC)∶w(MBN)为7.49~7.98;微生物碳熵(w(MBC)∶w(SOC))和氮熵(w(MBN)∶w(TN))的变化范围分别为1.09%~1.17%和1.34%~1.50%。Pearson相关分析表明,MBC、MBN质量分数与DOC、SOC、TN、凋落物生物量和细根生物量呈极显著正相关(P0.01)。通径分析表明,影响土壤MBC最重要的因子是细根生物量,其次是SOC;影响土壤MBN最重要的因素是细根生物量,其次是凋落物生物量。3种人工林的MBC和MBN质量分数、微生物碳氮熵与国内多数森林土壤相比均处于较低水平。

Microbial Biomass and Its Influence Factors in Topsoil of Three Different Plantations on A Sandy Coastal Plain

The experiment was conducted to study the effect factors of soil microbial biomass carbon (MBC) and nitrogen (MBN) of different plantations on a sandy coastal plain area in southeast Fujian,China.With three different plantations (Acacia cunninghamia,Acacia aulacocarpa,and Casuarina equisetifolia),the path analysis model was used to analyze the response of soil microbial biomass to soil physical and chemical properties,litter biomass (LB),and fine root biomass (FRB).The contents of MBC and MBN in the topsoil (0-10 cm depth) of three plantations were 42.60-51.56 and 5.38-6.88 mg · kg-1,respectively,with the C.equisetifolia plantation being the highest and higher than Acacia plantation (P＜ 0.05).The ratio of MBC to MBN was 7.49-7.98,that of MBC to SOC (Soil organic carbon) was 1.09％-1.17％,and that of MBN to TN (Total nitrogen) was 1.34％-1.50％.By correlation analysis,the MBC and MBN contents were significantly positively correlated with soil dissolved organic nitrogen (DOC),SOC,TN,LB,and FRB,respectively (P＜0.01).By path analysis,the FRB was the most important factors affecting MBC,followed by SOC,and the FRB was the important factors affecting MBN,followed by LB.Therefore,the MBC and MBN contents,MBC-to-SOC and MBN-to-TN of plantation soil under sandy coastal plain area were lower than those in the other area of China.