苏州生态景观林土壤微生物生物量及其化学计量特征

Soil microbial biomass and its stoichiometry under the eco-landscape forests in Suzhou city

本研究目的是调查苏州市不同生态景观林土壤微生物生物量及其化学计量特征,分析林分差异对土壤微生物生物量的影响,为城市生态景观林的构建提供微生物方面的基础数据。以苏州市香樟人工林(Cinnamomum camphora plantation)、喜树人工林(Camptotheca acuminata plantation)、水杉人工林(Metasequoia glyptostroboides plantation)、栾树人工林(Koelreuteria paniculata plantation)和池杉人工林(Taxodium distichum var.imbricatum plantation)5种生态景观林为研究对象,测定分析了各林分的0~20 cm、20~40 cm、40~60 cm、60~80 cm和80~100 cm 5个土壤层次全碳(TC)、全氮(TN)、全磷(TP)以及微生物生物量碳氮磷(MBC、MBN和MBP)。结果表明:(1)试验地各土层微生物生物量碳氮磷分别在447.0~957.1、1.4~56.2和1.2~3.3 mg·kg^(-1)之间,并且在不同景观林之间差异显著。其中,栾树人工林0~100 cm土壤具有较高MBC和MBN的平均含量,香樟人工林土壤则有较高的MBP平均含量。(2)林分类型对微生物生物量化学计量比(MBC∶MBN、MBC∶MBP、MBN∶MBP)、熵值(qMBC、qMBN和qMBP)以及土壤与微生物之间化学计量不平衡性有显著影响。其中,针叶林一般具有较高的MBC∶MBN、MBC∶MBP和qMBC,而阔叶林总体具有较高的MBN∶MBP、qMBN、qMBP和土壤-微生物之间化学计量不平衡性。(3)试验地土壤微生物生物量及其化学计量比主要与土壤容重、全碳、全氮以及全磷有显著或极显著相关关系。生态景观林类型显著影响0~100 cm土壤微生物生物量及其化学计量特征;相较于针叶林,阔叶林一般具有较高的MBN、MBP以及土壤-微生物之间化学计量不平衡性,表明阔叶林微生物生物量更易受土壤氮磷的影响。

The study aims to evaluate the effects of eco-landscape forest type on the microbial biomass and its stoichiometry at the depth of 0-100 cm soil for generating the basic data of carbon sequestration for the construction and management of urban forestry.The contents of total carbon(TC),total nitrogen(TN),total phosphorus(TP),microbial biomass carbon(MBC),microbial biomass nitrogen(MBN)and microbial biomass phosphorus(MBP)at the depths of 0-20 cm,20-40 cm,40-60 cm,60-80 cm and 80-100 cm were determined under five eco-landscape forests(i.e.,Cinnamomum camphora plantation,Camptotheca acuminata plantation,Metasequoia glyptostroboides plantation,Koelreuteria paniculata plantation and Taxodium distichum var.imbricatum plantation)in Suzhou city.The results showed that:(1)The contents of MBC,MBN,MBP in each soil layer were 447.0-957.1,1.4-56.2 and 1.2-3.3 mg⋅kg^(-1),respectively,which were significantly difference among the eco-landscape forests.The MBC and MBN contents at the depth of 0-100 cm soil were highest under Koelreuteria paniculata plantation,and the MBP was highest under Cinnamomum camphora plantation compared with the other eco-landscape forests.(2)The stoichiometric ratio(i.e.,MBC∶MBN,MBC∶MBP,MBN∶MBP),microbial entropy(i.e.,qMBC,qMBN,qMBP),and stoichiometric imbalance were significantly affected by forest type.The MBC∶MBN,MBC∶MBP and qMBC were higher in the soil of coniferous forest,but the MBN∶MBP,qMBN,qMBP and stoichiometric im-balance were higher in the soil of broad-leaved forest.(3)The microbial biomass and its stoichiometry were signifi-cantly correlated with bulk density,total carbon,total nitrogen and total phosphorus in the soil of the eco-landscape forests.The soil microbial biomass and its stoichiometry were significantly affected by the eco-landscape forest type.Compared with the coniferous forests,the broad-leaved forests had the higher MBN,MBP and stoichiometric im-balance in the soil,indicating that the soil microbial biomass of the broad-leaved forest was more susceptibly affect-ed by the total nitrogen and total phosphorus in the soil of the eco-landscape forests.