Abstract: Taking the 8-and 50-year-old Xanthoceras sorbifolia plantations in Wudan area of southwestern Horqin Sandy Lands as test objects, this paper studied the seasonal variation and nutrient resorption efficiency of their leaf N, P, and K. Throughout the growth season, the leaf N, P, and K concentrations in the two plantations had a decreasing trend, with the decrement being larger from May to June and from August to October, but less from June to August. The nutrient concentrations in living and fallen leaves, except the N concentration in fallen leaves, were significantly (P<0.01) higher in 8-year-old plantation than in 50-year-old plantation. The leaf nutrient resorption efficiency in 8-year-old plantation was in the order of N (50%) > P (32%) > K (30%), while that in 50-year-old plantation was in the order of K (63%) > P (62%) > N (48%). No significant difference (P>0.05) was observed in the leaf N resorption efficiency between 8-year-old and 50-year-old plantations. However, the leaf P and K resorption efficiency in 50-year-old plantation was significantly higher than that in 8-year-old plantation (P<0.01). On the whole, the leaf nutrientresorption efficiency in 50-year-old plantation was higher than that in 8-year-old plantation, reflecting the higher leaf nutrient conservation capability and use efficiency in 50-year-old X. sorbifolia plantation, and the better adaptation capability of this plantation to nutrient-poor habitat.

Key words: Localized compaction and ridge fertilization method, Nitrate transport, Nitrogen use efficiency