Abstract: Uncovering plant C, N, and P stoichiometric characteristics contributes to betterunderstanding of plant adaptation strategies. To clarify the responses of the contents and stoichiometry of main elements in dominant plant species to the cessation of N and P fertilization, a longterm field experiment was carried out to measure C, N, P contents in mature leaves of three main dominant species in a Horqin sandy grassland, including Chenopodium glaucum (collected in 2010), Phragmites australis (collected in 2010 and 2019), and Cannabis sativa (collected in 2019). The results showed that after the cessation of fertilization, foliar C content of the three dominant species did not differ significantly among the treatments. Two years after the cessation of N application (2010), foliar N content in Chenopodium glaucum significantly differed among the treatments (P=0.001). In the 2nd year after the cessation of P application, foliar P contents ofChenopodium glaucum and Phragmites australis were significantly differed among the treatments (P=0.000; P=0.029). Eleven years after the cessation of N and P fertilization, foliar N contents of Chenopodium glaucum, Phragmites australis did not differ significantly among the treatments. Foliar P content of Phragmites australisremained different in the P added plots while no difference in foliar P content of Cannabis sativawas observed. Foliar N∶P ratio was 5.33-12.63 and 19.78-24.63 for Chenopodium glaucum and Phragmites australis after two years of N and P cessation, respectively, and was 4.96-5.67 and 15.86-20.38 for Phragmites australisand Cannabis sativa after 11 years of fertilization cessation, respectively. The combined N and P fertilization promoted plant N and P absorption, with reversible and shortterm legacy effects of N and P addition on the foliar N and P contents of dominant species. Our results provide scientific basis for fertilization management in the restoration of Horqin grassland ecosystems.

Key words: nitrogen use efficiency, rice, nitrogen fertilizer, yield, quality.