中文摘要：

以内蒙古太卜寺旗地区退化沙质草地为研究对象,对该地区的小叶锦鸡儿灌丛化草地中的灌丛斑块和草地斑块分别取原状土柱各三个进行CT扫描,利用Fiji软件分析土壤孔隙结构特征的差异。研究结果表明,小叶锦鸡儿灌丛化对土壤的孔隙结构有较大影响,灌丛斑块土壤的总孔隙数、大孔隙数、总孔隙度、大孔隙度和孔隙等效直径均大于草地斑块土壤,灌丛斑块土壤的平均大孔隙度是草地斑块土壤的3倍。草地斑块土壤的大孔隙主要分布在0~50 mm土层深度,而灌丛斑块土壤的大孔隙在0~400 mm深度都有分布,这与土壤中灌丛的丰富根系分布有关。

英文摘要：

Samples of undisturbed soil core were collected, 3 each, from a shrub patch and a grass patch in a tract of degraded sandy grassland encroached by shrub, Caragana microphylla Lain, in Taibus Banner of Inner Mongolia. Anal- ysis of soil porosity is based on CT scanning and Fiji software, we analyze the pore parameters （ such as porosity ＆ equiva- lent diameter） with matlab based on 2D section images in every slice, and obtain trends of variations of pore parameters with depth. In additon, we can realize 3-D visualization of pores network with Fiji and qualitative description of soil pore distribution. Results show that shrub encroachment affected soil porosity and pore structure significantly. As a result, the soil in the shrub patch was much higher than that in the grass patch in total number of soil pores, number of macrospores （ 〉 1 000 μm） , total porosity, macroporosity, and mean of equivalent pore diameter, and especially in mean macroporosi- ty, the former was 3 times as high as the latter. In the grass patch, macropores were distributed mainly in the 0 -50 ram soil layer, while in the shrub patch, they were found throughout the 0 -400 mm soil layer, which is closely related to the well-developed root system of the shrubs.