Abstract: Nitrogen (N) and phosphorus (P) cycles control plant growth and development, community structure and function of grassland ecosystems. In order to define patterns of change in leaf N and P stoichiometry in Ningxia grasslands, and their main driving factors, leaf N and P contents were determined for 409 dominant plant species at 111 sampling sites. The geographic distribution of leaf stoichiometry patterns was analyzed in relation to the climatic factors, mean annual temperature (MAT) and mean annual precipitation (MAP), as well as altitude and latitude of the sampling site. The arithmetic means for leaf N and P content of Ningxia grassland plants were 22.47 and 1.83 mg·g^-1, respectively, and the mean N∶P ratio was 14.24. The growth of Ningxia grassland plants was limited by N and P. Leaf N and N∶P ratio increased with the increasing latitude and MAT, and with decreasing altitude and MAP. Leaf P increased with increase in MAP, while leaf N and P both increased with increased longitude. Spatial distribution and hydrothermal conditions explained 70.83% of the variance for leaf N, leaf P and N∶P ratio, indicating that the hydrothermal environment is the main driving factor for the Leaf N and P stoichiometry of Ningxia grassland plants. The results provide a theoretical basis for the management and improvement of productivity in Ningxia grassland.

Key words: Ningxia natural grassland plants, leaf N, P concentration, N/P ratio, stoichiometry characteristics