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

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.