Nitrogen and phosphorus resorption of Artemisia scoparia, Chenopodium acuminatum, Cannabis sativa, and Phragmites communis under nitrogen and phosphorus additions in a semiarid grassland, China

A factorial nitrogen (N) x phosphorus (P) addition experiment was conducted to evaluate responses of leaf nutrient resorption to increased soil N and P availability in a semiarid grassland in Keerqin Sandy Lands, China. Four plant species were selected, among which Artemisia scoparia and Chenopodium acuminatum were dominant species in the control and P-added plots, and Cannabis sativa and Phragmites communis were dominant in the N- and N + P-treated plots. Results showed that N and P resorption varied substantially among species (P < 0.01). A general trend of decrease in N resorption efficiency (NRE) and N resorption proficiency (NRP) was observed in response to increased soil N availability for all species, except P. communis only for NRE. Similarly, P resorption proficiency (PRP) decreased in response to P addition for all species, whereas P resorption efficiency (PRE) was not affected by P addition. Species responded differently in terms of PRE and PRP to N addition, whereas no changes in NRE and NRP occurred in response to P addition except P. communis for NRE. Our results suggest that increased soil nutrient availability can influence plant-mediated nutrient cycling directly by changing leaf nutrient resorption and indirectly by altering species composition in the sandy grassland.