Abstract: To evaluate the effects of mixed stands on nutrient limitation for Pinus tabuliformis growth,P. tabuliformis-Quercus mongolica and P. tabuliformis-Platycladus orientalis mixed stands in western Liaoning Province were selected and pure P. tabuliformis stand was taken as control. The concentrations of C, N, and P of P. tabuliformisleaves and soil were measured, and stoichiometric characteristics were analyzed. Results showed that P. tabuliformis-Q. mongolica mixed stand had a better capacity of improving soil fertility. P. tabuliformis-Q. mongolicamixed stand significantly increased soil C, N, and P concentrations, and significantly decreased C∶N and C∶P ratios of soil, leading to a higher N and P availability. The effects of P. tabuliformis-P. orientalis mixed stand on soil C∶N∶P stoichiometry were similar to that of P. tabuliformis-Q. mongolicamixed stand, but without statistical significance. N∶P ratio of P. tabuliformis leaf in themonoculture stands was higher than 16, while that under P. tabuliformis-Q. mongolicamixed stand and P. tabuliformis-P. orientalis mixed stand decreased to 14.88 and 14.02, respectively, indicating that the growth ofP. tabuliformisin monoculture was limited by P, which was improved by mixed stands. Foliar P concentration was not altered by both mixed stands; however, N concentration of leaf was decreased. Foliar C∶N and C∶P ratios were significantly associated with foliar N concentration, indicating that P. tabuliformis changed the stoichiometric characteristics of leaf due to that mixing stand improved soil P supply and N use efficiency.

Key words: blended fertilizer, nitrification inhibitor, regulation, soil nitrogen pool, urease inhibitor