滇西南亚热带山地主要植被类型下土壤微量元素状况研究

Research on the Microelements in the Soil of the Main Vegetation Types in the Subtropical Mountainous Zone of Southwest Yunnan

以滇西南澜沧县为研究区,研究了滇西南亚热带多年生常绿阔叶林、思茅松林和3 a生人工桉树林土壤中微量元素B,Cu,Zn,Fe,Mn的有效含量、分布规律,以及相似生境条件下三种植被类型对土壤微量元素的消耗状况及在土壤剖面中的垂直分布规律。结果表明:(1)不同植被类型的土壤中,有效Fe含量较为丰富,远高于临界值;而有效Zn,Mn,B含量很低,低于临界值,该地区属于Zn,Mn,B缺乏区;在常绿阔叶林和思茅松林下土壤中有效Cu的含量低于临界值,而在桉树林下土壤基本不缺Cu;(2)不同植被类型林下土壤微量元素的有效量有较大差异。常绿阔叶林下土壤中有效Fe,Zn的含量最高,有效Mn的含量最少;桉树林下土壤中有效Cu,Mn的含量最多,有效Zn的含量最少;松树林下土壤中微量元素都不多,其中有效Fe的含量最少;三种植被类型下土壤都缺少有效B元素;(3)相比较而言,在相似生境条件下,桉树林对有效Fe元素的消耗大于常绿阔叶林和思茅松林,但三种植被土壤中都不缺有效Fe;常绿阔叶林和思茅松林对有效Zn,Cu元素的消耗大于桉树林;常绿阔叶林对有效Mn的消耗大于桉树林,而桉树林对有效Mn的消耗大于思茅松林。且三种植被类型下土壤中都缺Zn,Mn,B,Cu微量元素;(4)各微量元素有效量在研究区土层中的分布规律因元素种类而异,少数元素与植被类型有关;在常绿阔叶林地中,随着土壤深度增加,有效Fe,Mn含量升高,有效Zn含量降低;而在生境条件相似的桉树林地中,随着土壤深度增加,有效Fe,Mn含量降低,其它元素则没有变化规律。在思茅松林地中,随着土壤深度增加,有效Fe,Mn含量降低;而在桉树林地中,随着土壤深度增加,有效Fe,Mn含量升高,其它元素则没有变化规律。

Choosing Lancang County as the research area,this paper studied the available content and the distribution regularity of the Microelements B,Cu,Zn,Fe and Mn in the forest of perennial evergreen broad-leaved forest,forest of pinus kesiya var.langbianensis and the man-made 3 a eucalyptus forest in the subtropical mountainous zone of southwest Yunnan.This paper also made research on the volume of the trace elements in the soil consumed by the three vegetation types in similar habitat condition and the vertical distribution regularity in the soil profile.The main conclusions are as follows：（1） In the soil of different vegetation types,the available content of Fe is above the critical level,but the available content of Zn,Mn and B is under the line.This area is lack of the elements of Zn,Mn and B.The available content of Cu in the soil of evergreen broad-leaved forest and forest of pinus kesiya var.langbianensis is below the critical level.However the soil in the eucalyptus forest is not lack of Cu.（2） There is a big difference in the available content of the microelements according to the soil of different vegetation types.The available content of Fe and Zn rank the first,and the available content of Mn is the lowest in the evergreen broad-leaved forest.The available content of Cu and Mn rank the first,and the available content of Zn is the lowest in the eucalyptus forest.All the microelements are more or less the same in the soil of pine forest with the lowest content of Fe.The available content of B is deficient in each vegetation type.（3） Comparatively the consumption of the available content of Fe in the eucalyptus forest is higher than the other two vegetations in the similar habitat condition,but available content of Fe is not deficient in each vegetation type.The consumption of Zn and Cu in the evergreen broad-leaved forest and forest of pinus kesiya var.langbianensis is higher than that in the eucalyptus forest.The consumption of Mn in the evergreen broad-leaved forest is higher than that in eucalyptus forest,and the consumption of Mn in the eucalyptus forest is higher than that in the forest of pinus kesiya var.langbianensis.The soil of all the three vegetations is lack of the microelements of Zn,Mn,B and Cu.（4） The distribution regularity of each microelement in the soil profile of the study area varies according to each element.The regularity of a few elements is related to the vegetation type.The available content of Fe and Mn is increasing with the depth of the soil in the evergreen broad-leaved forest,but the available content of Zn is decreasing.In the similar habitat condition of eucalyptus forest,the available content of Fe and Mn is decreasing with the depth of the soil.There is no evident regularity of other elements.The available content of Fe and Mn is decreasing with the depth of the soil of the forest of pinus kesiya var.langbianensis.The available content of Fe and Mn is increasing with the depth of the soil in the eucalyptus forest,and there is also no evident regularity of other elements.