Response of nutrient resorption ofLeymus chinensisto nitrogen and phosphorus addition in a meadow steppe of northeast China

Nutrient resorption, one of the most important strategies for plant nutrient conservation, is significantly affected by soil fertility. However, the effects of experimentally altered soil fertility on plant N and P resorption are poorly understood. The potential nutrient resorption response mechanisms of the dominant speciesLeymus chinensisto six N addition levels (0, 2.5, 5, 10, 20 and 40 g center dot N center dot m(-2)center dot year(-1)), two P addition levels (0 and 10 g P center dot m(-2)center dot year(-1)) and their interactions were studied after 3 years of treatments in a temperate meadow steppe. In both green leaves and culms, N and P addition significantly increased N and P concentrations, respectively. Nitrogen addition led to a decrease in the N resorption efficiency (NRE) of both leaves and culms. Within each N treatment, P addition decreased the P resorption efficiency (PRE) of both leaves and culms and the NRE of leaves, except in the N2.5 treatment. Both NRE and PRE in leaves were higher than those in culms under N and P addition conditions. The nutrient concentrations and resorption efficiency were significantly correlated with the soil nutrient availability. Our results suggest that plants rely more on nutrient absorption from the soil, reducing the proportion of elements obtained through nutrient resorption in nutrient-rich environments.