Nitrogen deposition influences the response of Potentilla tanacetifolia to phosphorus addition

Abstract

Phosphorus is an essential macronutrient for all livingplants and plant production. Simultaneously, atmospheric nitrogendeposition also affects plant productivity at a global scale. However,few studies have investigated how plants respond to P addition whilesimultaneously considering N deposition. We investigated plant biomass,nutrient status and stoichiometric ratios on Potentilla tanacetifoliain response to P fertilization under contrasting N addition ratesin a typical meadow steppe in Inner Mongolia, China. Abovegroundbiomass of P. tanacetifolia increased under increasing levels of P fertilizationunder conditions of N addition. However, there was no significantchange in biomass when only phosphorus was added. Plantleaf and stem P concentrations increased linearly with P additionwhen there was no N addition. Our results suggest that increasedplant P nutrition under P addition will not turn into plant growthenhancement unless N demands are also satisfied. Nitrogen additionsignificantly increased leaf N concentrations, and leaf and seed N:Pratios, when there was no P fertilization. Nevertheless, the effects ofN addition were weakened, and eventually disappeared when P fertilizationrates increased. This indicates that N-induced alterationsof the plant nutrition status and stoichiometric ratios were P availability-dependent. Overall, our results suggest that multiple-nutrientconstraints and their interactions must be considered when assessingplant nutrient and growth responses to nutrient enrichment.