Abstract: [Objective] This study aimed to investigate the variation of stoichiometry in soil under crown and in leaves of desert halophytes along soil salinity gradients, and the major soil factors that affect leaf stoichiometry of desert halophytes, which is of great significance to ecological conservation in drought and salinization zone.[Method] This study was conducted at the Ebinur Lake Wetland National Nature Reserve in Xinjiang Uygur Autonomous Region of China. Three plots with 10 m×10 m for each desert halophyte (Alhagi sparsifolia and Nitraria tangutorum) were set along soil salinity gradients. Based on the 216 samples of soil under crown and plant, the concentration of carbon (C), nitrogen (N) and phosphorus (P) and the ratios of C:N, C:P, and N:P in soil under crown and leaves of two desert halophytes in different soil salinity gradients were studied. Besides, the main soil properties that affect the leaf stoichiometry of the two halophytes were determined with redundancy analysis.[Result] The results showed that a modest increase in the soil salinity obviously improved C, N and P concentration in soil under crown of desert halophytes, while heavy salinity reduced C, N and P concentration in soil under crown of A. sparsifolia. The C:N, and C:P in soil under the crown of A. sparsifolia in medium salinity were the highest, while the largest values of N:P of A. sparsifolia and C:N, C:P, N:P of N. tangutorum appeared in light salinity plot, and, without striking difference with soil salinity gradient (P > 0.05). The concentration of C, N and P in leaves of N. tangutorum increased significantly with the increase of soil salinity (P < 0.05). The C:N, and C:P ratios under medium salinity treatment were greater than that under heavy salinity treatment. Light salinity increased the content of C and P in leaves of A. sparsifolia, but reduced N content. Medium salinity caused increases in C:N, and C:P in A. sparsifolia leaves. The leaf N:P of the two desert halophytes did not show a marked difference (P > 0.05) along with salinity gradient, and the average value was 15.41 ±2.16 and 8.01 ±0.83, respectively. Redundancy analysis showed that the P content in soil under crown, and salinity were the main factors that affect C, N and P stoichiometry in A. sparsifolia and N. tangutorum leaves, respectively.[Conclusion] A modest increase in soil salinity improved the content of C, N, P in the soil under crown, and changed the content of C, N, P and the C:P ratio in leaves of the two desert halophytes. Leaf stoichiometry of halophytes was influenced by salinity and sodicity as well as element content in soil, and the interspecific difference resulted in the difference in main soil factor that affected leaf stoichiometry of the two desert halophytes.

Key words: Alhagi sparsifolia, Nitraria tangutorum, soil salinity gradients, ordination, redundancy analysis