基于工业CT扫描研究喀斯特地区土壤大孔隙结构特征

Study on Characteristics of Soil Macropore Structure in Karst Area Based on Industrial CT Scanning

  • 摘要: 以云南省建水县喀斯特地区的天然次生林、人工云南松纯林、灌木及天然草本共4种植被类型为研究对象,利用拓扑原理及工业CT扫描技术,识别研究区4种植被类型条件下的土壤大孔隙网络结构,并结合VG Studio MAX软件,定量分析大孔隙的弯曲度、扭曲度、趋向性等特征。结果表明:4种植被类型的土壤持水量依次为天然草地>灌木>天然次生林>人工云南松纯林,土壤毛管孔隙度依次为灌木>草地>人工云南松纯林>天然次生林,天然草地无深层根系但破碎程度高,人工林20~30 cm深的土壤破碎程度更低,且人工林的累积扭曲度接近天然次生林和天然草地的1.30倍,因此人工恢复后的土壤结构复杂,可有效延长土壤水分的滞留时间。坡下大孔隙在有、无根系的条件下,均具有明显的偏向性,且不对称。4种植被类型的大孔隙偏向性依次为天然次生林>人工云南松纯林>灌木>天然草地。

     

    Abstract: The secondary forest, Pinus yunnanensis plantation forest, shrub and natural grassland in karst area of Jianshui County were selected as the research objects. The topological principle and industrial CT scanning technology were used to identify the soil macropore network structure in the study area, and VG Studio MAX software was used to quantitatively analyze the curvature, twist degree and porosity. The results showed that the soil water capacity of 4 vegetation types was grassland > shrub > secondary forest > P. yunnanensis plantation forest, and the soil capillary porosity was shrub > grassland > P. yunnanensis plantation forest > secondary forest. Natural grassland had no deep roots, but the soil is broken. The soil fragmentation in 20–30 cm depth of P. yunnanensis plantation forest decreased effectively, and the cumulative twist degree is close to 1.3 times that of natural secondary forest and natural grassland. The soil structure after artificial restoration was complex, which can effectively prolong the retention time of soil water. Under the condition of root system or not, the macropores had obvious deviation and no symmetry. The macropore bias of the 4 vegetation types was secondary forest >P. yunnanensis plantation forest > shrub > grassland.

     

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