Abstract: In this paper,the fractal characteristics of the whole-roots,primary lateral roots and secondary lateral roots of three-year-old Hippophae rhamnoides planted on different slope aspects and gradients were analyzed based on the fractal theory. The relations between the growth and development of the roots and soil moisture content in a sandstone area were studied. The results are as follows: ① The variations of fractal dimensions were in orders of D_ES>D_NS>D_SS>D_WS,D_50°S>D_40°S,fractal dimensions of secondary lateral roots (D1)>fractal dimensions ofwhole-roots (D)>fractal dimensions of primary lateral roots (D2) under different site conditions. There was a significant positive correlation between D1 and fine roots length; ② The topsoil moisture content on the southern and western slopes was lower than 4%,which was not conducive to the development of root system. The soil moisture content on the northern and eastern slopes was high,so the fractal dimensions of these two slopes were higher compared with that for the root growth of H.rhamnoides on the northern and western slopes,and the moderate lack of water on the eastern (southern) slope could stimulate the fine roots to grow down to deep soil; ③ H.rhamnoides could adapt to the environment through root fractal regulation when water is insufficient,but its growth conditions were not as good as that when water is sufficient. Therefore,the growth conditions were in orders of northern slope>eastern slope>western slope>southern slope,and 40°slope>50°slope. It is suggested that the priority should be given to the northern and eastern slopes when planting H.rhamnoides,and the slope steeper than 50° is not conducive to the growth of H.rhamnoides.

Key words: Hippophae rhamnoides, root, fractal dimension, slope stabilization, sandstone area, Inner Mongolia