title: Intensified plant N and C pool with more available nitrogen under experimental warming in an alpine meadow ecosystem.
abstract: Nitrogen (N) availability is projected to increase in a warming climate. But whether the more available N is immobilized by microbes (thus stimulates soil carbon (C) decomposition), or is absorbed by plants (thus intensifies C uptake) remains unknown in the alpine meadow ecosystem. Infrared heaters were used to simulate climate warming with a paired experimental design. Soil ammonification, nitrification, and net mineralization were obtained by in situ incubation in a permafrost region of the Qinghai-Tibet Plateau (QTP). Available N significantly increased due to the stimulation of net nitrification and mineralization in 0-30 cm soil layer. Microbes immobilized N in the end of growing season in both warming and control plots. The magnitude of immobilized N was lower in the warming plots. The root N concentration significantly reduced, but root N pool intensified due to the significant increase in root biomass in the warming treatment. Our results suggest that a warming-induced increase in biomass is the major N sink and will continue to stimulate plant growth until plant N saturation, which could sustain the positive warming effect on ecosystem productivity.
authors.affiliation: key laboratory of desert and desertification northwest institute of eco-environment and resource Chinese Academy of Sciences.
authors.forename: Fei
authors.initials: F
authors.lastname: Peng
authors.affiliation: key laboratory of desert and desertification northwest institute of eco-environment and resource Chinese Academy of Sciences.
authors.forename: Xian
authors.initials: X
authors.lastname: Xue
authors.affiliation: key laboratory of desert and desertification northwest institute of eco-environment and resource Chinese Academy of Sciences; University of Chinese Academy of Sciences Beijing China.
authors.forename: Quangang
authors.initials: Q
authors.lastname: You
authors.affiliation: Taiyuan Normal University Taiyuan China.
authors.forename: Manhou
authors.initials: M
authors.lastname: Xu
authors.affiliation: key laboratory of desert and desertification northwest institute of eco-environment and resource Chinese Academy of Sciences; University of Chinese Academy of Sciences Beijing China.
authors.forename: Xiang
authors.initials: X
authors.lastname: Chen
authors.affiliation: key laboratory of desert and desertification northwest institute of eco-environment and resource Chinese Academy of Sciences.
authors.forename: Jian
authors.initials: J
authors.lastname: Guo
authors.affiliation: key laboratory of desert and desertification northwest institute of eco-environment and resource Chinese Academy of Sciences.
authors.forename: Tao
authors.initials: T
authors.lastname: Wang
keywords: alpine meadow; incubation; infrared heater; microbial biomass; mineralization