城乡梯度3种林分类型土壤酶活性及影响因素

Soil enzyme activities and influencing factors of three forest types under the urban-rural gradient

以广州市城区、近郊和乡村森林土壤为研究对象,探讨马尾松林、针阔混交林和常绿阔叶林土壤酶活性特征及其与理化性质和重金属之间的关系。结果表明:马尾松林土壤酸性磷酸酶(AP)、脲酶(URE)活性以及针阔混交林土壤过氧化氢酶(CAT)、URE、脱氢酶(DH)活性均为近郊>乡村>城区,而常绿阔叶林土壤AP、URE、DH活性为近郊>城区>乡村。城区、近郊针阔混交林土壤pH值、砂粒含量均显著高于马尾松林和常绿阔叶林(P<0.05);土壤有机质(SOM)、总氮(TN)、总磷(TP)含量均为马尾松林<针阔混交林<常绿阔叶林;乡村针阔混交林土壤SOM含量、阳离子交换量(CEC)、黏粒含量、粉粒含量、含水率在3种林分中均最低。城区马尾松林土壤重金属铜(Cu)、锌(Zn)、铅(Pb)含量在3种林分间均最低,而镉(Cd)含量在3种林分间相同;近郊、乡村常绿阔叶林土壤重金属Zn、Pb含量在3种林分中均最高。土壤含水率、SOM含量、pH值、CEC、Cu含量、黏粒含量、TN含量是土壤酶活性的主要影响因子。相关性分析表明,土壤SOM、TN含量与土壤CAT、AP活性呈显著正相关(P<0.05);土壤TP含量与土壤AP、URE活性呈显著正相关(P<0.05);土壤含水率与土壤DH活性呈显著正相关(P<0.05);而土壤Cu含量与URE活性呈显著负相关(P<0.05)。

Soil samples were collected from the forests[Pinus massoniana forest(PF),mixed coniferous and broadleaf forest(MF),broad-leaved evergreen forest(BF)]in the urban area,suburban area,and rural area of Guangzhou City to explore the changes of soil enzyme activities and their relationship with physicochemical properties and heavy metals.Those results showed that:the acid phosphatase(AP)and urease(URE)activities in PF and the catalase(CAT),URE and dehydrogenase(DH)activities in MF showed the same trend of suburban>rural>urban.The AP,URE and DH activities in BF showed a trend of suburban>urban>rural.From urban to suburban,the soil pH value and the content of sand in MF were significantly higher than PF and BF(P<0.05),and the contents of soil organic matter(SOM),total nitrogen(TN),total phosphorus(TP)showed a trend of PF<MF<BF.The contents of SOM,cation exchange capacity(CEC),clay,silt,moisture of MF in rural were the lowest.The contents of copper(Cu),zinc(Zn),and lead(Pb)of PF in urban were the lowest,while cadmium(Cd)content was the same among three forest types.The contents of Zn and Pb of BF in suburban and rural were the highest.The soil moisture,SOM,pH,CEC,Cu,clay and TN were the main factors affecting soil enzyme activities.Correlation analysis indicated that,SOM,TN were significantly and positively correlated with CAT and AP(P<0.05),TP were significantly and positively correlated with AP and URE(P<0.05),soil moisture were significantly and positively correlated with DH(P<0.05).Nevertheless,the contents of Cu were significantly and negatively correlated with URE(P<0.05).