晋西黄土区果农间作系统根系生态位特征

为了进一步分析农林复合系统的土壤水肥效应，指导农林复合系统的物种选择和行间配置及其水肥管理等农艺措施，以晋西黄土区核桃—大豆间作系统为研究对象，采用分层挖掘根系法，研究核桃和大豆的根系生态位分布特征及地下种间竞争关系。结果表明，在1.0~3.0 m各区域，核桃根系生态位宽度均大于大豆根系生态位宽度，而在3.0~3.5 m区域，则反之；在垂直方向上，除1.5~2.0 m区域的大豆外，大豆和核桃的根系生态位均随土壤深度的增加而下降；距树行1.0~3.0 m各区域，核桃对大豆的生态位重叠指数均大于大豆对核桃的生态位重叠指数，而在距树行3.0~3.5 m区域，则反之。距树行1.0~2.5 m区域的核桃和大豆根系生态位相似性和地下种间竞争指数均较大，为种间土壤水肥竞争的主要区域。

Niche of Roots in the Economic Tree and Crop Intercropping System in the Western Shanxi Province of Loess Plateau

In order to further study the soil water and fertilizer effect of agroforestry system and guide species selection, spacing form, tillage and fertilize. A walnut-soybean intercropping system in the western Shanxi Province of Loess Plateau was used as material. Distribution of niche and underground competition characteristics of roots in a walnut-soybean intercropping system were examined by stratified digging method. The results showed that niche breadths of walnut roots were higher than that of soybean in plots 1.5-3.0 m from the tree row but it was the opposite situation in plot 3.0-3.5 m, niche breadth of roots for both walnut and soybean were decreased with the depth except for that of soybean in plot 1.5-2.0 m, niche overlap of soybean roots were lower than that of walnut in plots 1.5-3.0 m from the tree row beside the plot 3.0-3.5 m. Both niche similarity of roots and underground species competitive index between walnut and soybean were greater in the 1.0-2.5 m from the tree row, where is the main area competing for soil moisture and nutrients.