Abstract:Increased atmospheric nitrogen (N) deposition may adjust the nutrient resorption efficiency of the plant species in the coastal wetlands due to the changing of soil nutrients availability. Most studies concentrated on the nutrient resorption of the leaf, whereas the nutrient resorption of the non-leaf organs, such as culm, is still less known. Moreover, little attention is concentrated on differentiating the effects of nitrate and ammonium additions on nutrient resorption. In this study, an in situ experiment was conducted to investigate the effects of nitrate and ammonium additions on the nutrient resorption efficiency of leaf and culm for reed (Phragmites australis) in the coastal wetlands of the Yellow River Delta, China. Results showed that N additions increased the concentrations of N and phosphorus (P) in senesced organs, ranging from 32.71% to 43.22% for N, and ranging from 30.91% to 36.51% for P. The N resorption efficiency (NRE) ranged from 54.14% to 67.66% for the leaf and ranged from 50.60% to 62.85% for the culm. The P resorption efficiency (PRE) ranged from 56.80% to 70.38% for the leaf and ranged from 77.43% to 84.95% for the culm. Both two types of N addition had similar and negative effects on nutrient resorption efficiency (P<0.001). The NRE of leaf was similar to that of culm, whereas the culm had larger PRE than leaf (P<0.01). Overall, both N additions decreased the NRE and PRE of reed. Furthermore, the culm of reed had a non-negligible contribution to nutrient resorption.