【摘要】 基于分形理论,对砒砂岩区内人工种植在不同坡向和坡度下的3 a生沙棘的全根、一级侧根及二级侧根的分形特征,以及沙棘根系生长发育与不同立地下土壤含水率之间的关系进行了研究。结果表明:①分形维数变化为D_东坡> D_北坡> D_南坡> D_西坡,D50°> D40°,不同立地下D₁（二级侧根分形维数）> D（全根分形维数）> D₂（一级侧根分形维数）,且D₁与细根根长呈显著正相关。②南坡与西坡土壤表层含水率低于4%,不利于根系发育,北坡与东坡含水率较高,所以,北坡与东坡分形维数较大;与北坡（西坡）生长的沙棘相比,东坡（南坡）坡面适度的缺水条件刺激了细根向深土层生长,利用深土层水分。③沙棘在水分不足时能够通过调节根系分形适应环境,但是生长状况不如水分充足时好,因此沙棘的生长状况为北坡>东坡>西坡>南坡,40°坡面> 50°坡面。在砒砂岩区不同立地下,种植沙棘建议优先选择北坡与东坡,次选西坡与南坡,而50°坡不利于沙棘生长。更多还原

【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,D50° S> D40° 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.更多还原