岩溶区原始林土壤微量元素含量与有效特征

Contents and availability of trace elements in soils of natural forests in karst region

以贵州茂兰、海南俄贤岭、云南西双版纳勐远仙境国家公园和绿石林自然保护区内具有典型岩溶地貌特征的原始林为研究对象,调查岩溶原始林地土壤4种微量元素(Cu、Fe、Mn、Zn)全量和有效态含量。结果表明,岩溶区原始林地土壤全铜、全铁、全锰和全锌含量分别为0.03~0.08g·kg^(-1)、35.6~57.4g·kg^(-1)、0.74~5.83g·kg^(-1)和0.13~1.03g·kg^(-1),均超过国家背景值的平均值。研究区土壤Cu、Fe、Mn和Zn有效态含量分别为1.09~3.51mg·kg^(-1)、11.6~62.9mg·kg^(-1)、48.3~173mg·kg^(-1)和4.17~37.6mg·kg^(-1),根据土壤微量元素有效态评价标准,4种微量元素有效态含量均处于较高水平。原始林地土壤Cu、Fe、Mn和Zn的活化率均值分别为5.48%、0.10%、6.44%、4.19%,表明岩溶区森林土壤Cu、Mn和Zn供素水平高,Fe供素水平低。4个原始林地土壤微量元素有效性综合指数(E_t)为茂兰(21.0)>绿石林(12.8)≈勐远(12.7)>俄贤岭(5.15),且Et与全氮和有机碳含量呈显著的正相关。

Soil under undisturbed natural forests were sampled to investigate total and available contents of four trace elements（Cu,Fe,Mn and Zn）from four nature reserves including Maolan in Guizhou,Mengyuan and Green Stone Forest in Yunnan,and Exianling in Hainan,all of which were characterized by typical karst landform.The results showed total content of Cu,Fe,Mn and Zn reached to 0.03~0.08 g·kg^（-1）,35.6~57.4 g·kg^（-1）,0.74~5.83 g·kg^（-1） and 0.13~1.03 g·kg^（-1）,respectively,which were significantly higher the average national background values.The available content of Cu,Fe,Mn and Zn in study areas were 1.09~3.51 mg·kg^（-1）,11.6~62.9 mg·kg^（-1）,48.3~173 mg·kg^（-1） and 4.17~37.6 mg·kg^（-1）,respectively.According to the evaluation standard for trace elements in soil,available contents of all four elements were at relatively high level.The average activation ratios of Cu,Fe,Mn and Zn in soils under the natural forest were 5.48%,0.10%,6.44% and 4.19%,respectively,indicating high supply level for Cu,Mn and Zn but low supply level for Fe.Total availability index of trace element（Et）in soil was ranked as Maolan（21.0）Green Stone Forest（12.8）≈Mengyuan（12.7）Exianling（5.15）.In addition,Et was significantly positively correlated with total N and organic carbon contents.