Vol14 No.3: 474-491
【Title】Quantification of 3D macropore networks in forest soils in Touzhai valley (Yunnan, China) using X-ray computed tomography and image analysis
【Author】ZHANG Jia-ming1; XU Ze-min1*; LI Feng2; HOU Ru-ji3; REN Zhe1
【Addresses】1 Department of Civil Engineering, Kunming University of Science and Technology, Kunming 650500, China; 2 Department of Earth Sciences, Kunming University of Science and Technology, Kunming 650093, China; 3 Water Transportation Planning and Design Institute of Yunnan, Kunming 650051, China
【Citation】Zhang JM, Xu ZM, Li F, et al. (2017) Quantification of 3D macropore networks in forest soils in Touzhai valley (Yunnan, China) using X-ray computed tomography and image analysis. Journal of Mountain Science 14(3). DOI: 10.1007/s11629-016-4150-9
【Abstract】The three dimensional (3D) geometry of soil macropores largely controlspreferential flow, which is a significant infiltrating mechanism for rainfall in forest soils and affects slope stability. However, detailed studies on the 3D geometry of macropore networks in forest soils are rare.The intense rainfall-triggered potentially unstable slopes were threateningthe villages at the downstream of Touzhai valley (Yunnan, China). Wevisualizedand quantifiedthe 3D macropore networks in undisturbed soil columns (Histosols) taken from a forest hillslope in Touzhai valley, and compared them with those in agricultural soils (corn and soybean in USA; barley, fodder beet and red fescue in Denmark) and grassland soils in USA. We took two large undisturbed soil columns (250 mm×250 mm×500 mm), and scanned the soil columns at in-situ soil water content conditions using X-ray computed tomography at a voxel resolution of 0.945 × 0.945 × 1.500 mm3. After reconstruction and visualization, we quantiﬁedthe characteristics of macropore networks. In the studied forest soils, the main types of macropores were root channels, inter-aggregate voids, macropores without knowing origin, root-soil interface and stone-soil interface. Whilemacropore networks tend to be more complex, larger, deeper and longer. The forest soils have high macroporosity, total macropore wall area density, node density, and large macropore volume, hydraulic radius, mean macropore length, angle, and low tortuosity. The findings suggest that macropore networks in the forest soils have high inter-connectivity, vertical continuity, linearity and less vertically oriented.
【Keywords】Slope stability; Touzhai valley; Rainfall infiltration; Forest soils; X-ray computed tomography; 3D macropore networks