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ELEVATED CO 2 STIMULATES NET ACCUMULATIONS OF CARBON AND NITROGEN IN LAND ECOSYSTEMS: A META‐ANALYSIS
Author(s) -
Luo Yiqi,
Hui Dafeng,
Zhang Deqiang
Publication year - 2006
Publication title -
ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.144
H-Index - 294
eISSN - 1939-9170
pISSN - 0012-9658
DOI - 10.1890/04-1724
Subject(s) - ecosystem , shoot , biomass (ecology) , litter , nitrogen , soil carbon , terrestrial ecosystem , plant litter , environmental science , agronomy , ecology , soil organic matter , soil water , chemistry , biology , organic chemistry
The capability of terrestrial ecosystems to sequester carbon (C) plays a critical role in regulating future climatic change yet depends on nitrogen (N) availability. To predict long‐term ecosystem C storage, it is essential to examine whether soil N becomes progressively limiting as C and N are sequestered in long‐lived plant biomass and soil organic matter. A critical parameter to indicate the long‐term progressive N limitation (PNL) is net change in ecosystem N content in association with C accumulation in plant and soil pools under elevated CO 2 . We compiled data from 104 published papers that study C and N dynamics at ambient and elevated CO 2 . The compiled database contains C contents, N contents, and C:N ratio in various plant and soil pools, and root:shoot ratio. Averaged C and N pool sizes in plant and soil all significantly increase at elevated CO 2 in comparison to those at ambient CO 2 , ranging from a 5% increase in shoot N content to a 32% increase in root C content. The C and N contents in litter pools are consistently higher in elevated than ambient CO 2 among all the surveyed studies whereas C and N contents in the other pools increase in some studies and decrease in other studies. The high variability in CO 2 ‐induced changes in C and N pool sizes results from diverse responses of various C and N processes to elevated CO 2 . Averaged C:N ratios are higher by 3% in litter and soil pools and 11% in root and shoot pools at elevated relative to ambient CO 2 . Elevated CO 2 slightly increases root:shoot ratio. The net N accumulation in plant and soil pools at least helps prevent complete down‐regulation of, and likely supports, long‐term CO 2 stimulation of C sequestration. The concomitant C and N accumulations in response to rising atmospheric CO 2 may reflect intrinsic nature of ecosystem development as revealed before by studies of succession over hundreds to millions of years.