Abstract: Sophora alopecuroides is a mid-xerotrophic and salt-tolerant plant species that grows mostly in deserts and semi-desert areas. It is one of the typical poisonous grasses in the mountain grasslands of the Yili River Valley in Xinjiang. Root is the important organ for absorbing soil nutrients. In this study, we collected roots and rhizosphere soil of S. alopecuroides in four different habitats (forest, wasteland, roadside, and cropland) in the Yili River Valley to analyze their stoichiometric characteristics and the relationship between stoichiometric characteristics of S. alopecuroides roots and soil physicochemical factors by redundancy analysis. The results showed that the average root C, N, and P concentrations were 422.99, 10.06, and 1.16 g·kg^-1, respectively. Among those three elements, the coefficient of variation of N concentration was the largest (0.25), and that of P concentration was the smallest (0.17). The C/N ratio was 9.93, C/P ratio was 10.54, and N/P ratio was 1.06. We quantified the importance of soil physical and chemical factors to the stoichiometric characteristics of S. alopecuroides roots in different habitats by redundancy analysis. The importance of all the factors ranked as available potassium > nitrate > total carbon > available phosphorus > organic matter > total phosphorus > pH > total potassium > total nitrogen > ammonium in forest habitat; as ammonium > pH > total phosphorus > available potassium > total potassium > organic matter > total carbon > available phosphorus > total nitrogen > nitrate in roadside habitat; as organic matter > pH > available potassium > nitrate > available phosphorus > total phosphorus > total carbon > total potassium > total nitrogen > ammonium in uncultivated land; as organic matter > nitrate > total nitrogen > pH > available potassium > total carbon > available phosphorus > total potassium > ammonium > total phosphorus in cropland habitat. Our results provide a theoretical basis for controlling poisonous grasses in the Yili mountain grassland.

Key words: habitat, Sophora alopecuroides, root, stoichiometric characteristics, soil physical and chemical factors.