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Linkages of plant stoichiometry to ecosystem production and carbon fluxes with increasing nitrogen inputs in an alpine steppe
Author(s) -
Peng Yunfeng,
Li Fei,
Zhou Guoying,
Fang Kai,
Zhang Dianye,
Li Changbin,
Yang Guibiao,
Wang Guanqin,
Wang Jun,
Yang Yuanhe
Publication year - 2017
Publication title -
global change biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.146
H-Index - 255
eISSN - 1365-2486
pISSN - 1354-1013
DOI - 10.1111/gcb.13789
Subject(s) - primary production , ecosystem , ecosystem respiration , terrestrial ecosystem , environmental science , steppe , nitrogen , productivity , biosphere , carbon cycle , soil respiration , ecology , atmospheric sciences , agronomy , environmental chemistry , chemistry , biology , macroeconomics , organic chemistry , economics , geology
Unprecedented levels of nitrogen (N) have entered terrestrial ecosystems over the past century, which substantially influences the carbon (C) exchange between the atmosphere and biosphere. Temperature and moisture are generally regarded as the major controllers over the N effects on ecosystem C uptake and release. N‐phosphorous (P) stoichiometry regulates the growth and metabolisms of plants and soil organisms, thereby affecting many ecosystem C processes. However, it remains unclear how the N‐induced shift in the plant N:P ratio affects ecosystem production and C fluxes and its relative importance. We conducted a field manipulative experiment with eight N addition levels in a Tibetan alpine steppe and assessed the influences of N on aboveground net primary production ( ANPP ), gross ecosystem productivity ( GEP ), ecosystem respiration ( ER ), and net ecosystem exchange ( NEE ); we used linear mixed‐effects models to further determine the relative contributions of various factors to the N‐induced changes in these parameters. Our results showed that the ANPP , GEP , ER , and NEE all exhibited nonlinear responses to increasing N additions. Further analysis demonstrated that the plant N:P ratio played a dominate role in shaping these C exchange processes. There was a positive relationship between the N‐induced changes in ANPP (Δ ANPP ) and the plant N:P ratio (ΔN:P), whereas the Δ GEP , Δ ER , and Δ NEE exhibited quadratic correlations with the ΔN:P. In contrast, soil temperature and moisture were only secondary predictors for the changes in ecosystem production and C fluxes along the N addition gradient. These findings highlight the importance of plant N:P ratio in regulating ecosystem C exchange, which is crucial for improving our understanding of C cycles under the scenarios of global N enrichment.