岩溶区不同植被演替过程中土壤元素及其有效态

Soil Elements Level and Availability in Different Vegetation Succession Stages in Karst Area

[目的]探讨岩溶区不同植被演替过程中土壤元素及其有效态变化规律,为岩溶区石漠化治理提供依据。[方法]采用空间代替时间序列的方法,选取立地条件相似的草地、灌草丛、灌丛、乔幼林和顶级乔林5个植被恢复阶段进行分析。[结果]同一植被类型条件下有机质的含量浅层大于深层;元素的迁移能力在垂向上:在植被演替的早期阶段浅层大于深层,后期深层土大于浅层;在横向上:乔幼林>顶级乔林>灌草丛>草地>灌丛;随着植被的演替土壤中有机质呈波浪式的增加,并在顶级乔林阶段达到最大值;土壤有机质含量与Mn,Zn,Cu元素有效态含量呈明显的正相关。受此影响,浅层土壤元素态有效率明显高于深层土壤。[结论]石漠化治理过程中应针对石漠化地区土层厚度、地形、土壤元素分布特征,选择合理的植被进行恢复。

[Objective]To explore the variations of soil elements and their availabilities in different vegetation successional stages in karst region in order to provide a certain basis for the treatment of rocky desertification.[Methods]Method of investigation in different spatial sites instead of time-series sampling was used.Sites at five different vegetation stages as grass,grass-shrub,shrub,earlier arbor,arbor climax with the same geological backgrounds were investigated and sampled.[Results]The organic matter contents of five vegetation types in shallow soil are all higher than that in deep soil.The elements migration in the vertical direction showed that in shallow soil horizons are all higher than that in deep soil horizons at the early vegetation successional stage and indicate the opposite trend at the late stage.Meanwhile,the elements migration in the horizontal direction indicate the order of earlier arbor stage,climax arbor stage,grass-shrub stage,grass stage,and shrub stage.The soil organic matter showed wavy increase with the vegetation succession and reached the maximum value at climax arbor stage.The availabilities of Mn,Zn,Cu had positive correlations with soil organic matter.Therefore,the soil elements availabilities in shallow soil were higher than that in deep soil.[Conclusion]To deal with the rocky desertification,items of soil thickness,topography and soil element distribution characteristics should be concerned to select reasonable revegetation measures.