title: Down-regulation of tissue N:P ratios in terrestrial plants by elevated CO2.
abstract: Increasing atmospheric CO2 concentrations generally alter element stoichiometry in plants. However, a comprehensive evaluation of the elevated CO2 impact on plant nitrogen: phosphorus (N:P) ratios and the underlying mechanism has not been conducted. We synthesized the results from 112 previously published studies using meta-analysis to evaluate the effects of elevated CO2 on the N:P ratio of terrestrial plants and to explore the underlying mechanism based on plant growth and soil P dynamics. Our results show that terrestrial plants grown under elevated CO2 had lower N:P ratios in both above- and belowground biomass across different ecosystem types. The response ratio for plant N:P was negatively correlated with the response ratio for plant growth in croplands and grasslands, and showed a stronger relationship for P than for N. In addition, the CO2-induced down-regulation of plant N:P was accompanied by 19.3% and 4.2% increases in soil phosphatase activity and labile P, respectively, and a 10.1% decrease in total soil P. Our results show that down-regulation of plant N:P under elevated CO2 corresponds with accelerated soil P cycling. These findings should be useful for better understanding of terrestrial plant stoichiometry in response to elevated CO2 and of the underlying mechanisms affecting nutrient dynamics under climate change.
authors.forename: Qi
authors.initials: Q
authors.lastname: Deng
authors.forename: Dafeng
authors.initials: D
authors.lastname: Hui
authors.forename: Yiqi
authors.initials: Y
authors.lastname: Luo
authors.forename: James
authors.initials: J
authors.lastname: Elser
authors.forename: Ying-ping
authors.initials: YP
authors.lastname: Wang
authors.forename: Irakli
authors.initials: I
authors.lastname: Loladze
authors.forename: Quanfa
authors.initials: Q
authors.lastname: Zhang
authors.forename: Sam
authors.initials: S
authors.lastname: Dennis
mesh_terms: D002245:Carbon Dioxide / Q000737:chemistry / Q000494:pharmacology*; D057231:Climate Change; D015536:Down-Regulation / Q000502:physiology*; D009584:Nitrogen / Q000378:metabolism*; D010758:Phosphorus / Q000737:chemistry / Q000378:metabolism*; D010944:Plants / Q000187:drug effects* / Q000378:metabolism*; D012987:Soil / Q000737:chemistry
chemical_list: D012987:Soil; D002245:Carbon Dioxide; D010758:Phosphorus; D009584:Nitrogen