LAUSR

Background Sophora alopecuroides L. (S. alopecuroides L.) is a perennial herb widely distributed throughout Xinjiang, China. It is characterized by its rapid diffusion ability. Methods To reveal the ecological mechanism of the rapid spread of S. alopecuroides, and to elucidate the ecological stoichiometric characteristics of C, N, and P (and the influencing factors) in the leaves of S. alopecuroides, leaves were sampled from four habitats—forest, roadside, farmland, and desert—across the Yili River Valley. The variation rules of the ecological stoichiometric characteristics of C, N, and P in the leaves of S. alopecuroides were analyzed. Correlations between the ecological stoichiometric characteristics of leaves and environmental factors were examined using redundancy analysis (RDA). Results (1) The C, N, and P contents of S. alopecuroides leaves were 391.30–533.10 g/kg, 8.90–43.14 g/kg, and 0.71–2.04 g/kg, respectively, and the C/N, C/P, and N/P ratios were 10.34–4.94, 209.05–698.73, and 10.78–31.43 respectively. (2) The C content and C/P ratio of S. alopecuroides leaves were the highest in the desert habitat, leaf N content and N/P ratio were the highest in the forest habitat, leaf P content was the highest in the farmland habitat, and the leaf C/N ratio was the highest in the roadside habitat. (3) RDA showed that available potassium (AK) and pH were the main factors affecting the ecological stoichiometric characteristics of S. alopecuroides leaves in Yili Valley (p ≤ 0.05), and these factors were positively correlated with C, N, P, and N/P, and negatively correlated with C/P and C/N. AK was the dominant factor that affected the P content of S. alopecuroides leaves, and appropriate reduction of K fertilizer would be conducive to restraining the spread of S. alopecuroides. Soil C, N, P, and K content, soil organic matter (OM), nitrate nitrogen (NO3−-N), ammonium nitrogen (NH4+-N), and AK had no significant effect on the ecological stoichiometric characteristics of leaves (p > 0.05).