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Hierarchical saturation of soil carbon pools near a natural CO 2 spring
Author(s) -
KOOL DORIEN M.,
CHUNG HAEGEUN,
TATE KEVIN R.,
ROSS DES J.,
NEWTON PAUL C. D.,
SIX JOHAN
Publication year - 2007
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/j.1365-2486.2007.01362.x
Subject(s) - saturation (graph theory) , soil carbon , soil science , environmental science , environmental chemistry , sink (geography) , carbon sink , chemistry , hydrology (agriculture) , soil water , ecology , ecosystem , geology , mathematics , biology , geography , cartography , geotechnical engineering , combinatorics
Soil has been identified as a possible carbon (C) sink to mitigate increasing atmospheric CO 2 concentration. However, several recent studies have suggested that the potential of soil to sequester C is limited and that soil may become saturated with C under increasing CO 2 levels. To test this concept of soil C saturation, we studied a gley and organic soil at a grassland site near a natural CO 2 spring. Total and aggregate‐associated soil organic C (SOC) concentration showed a significant increase with atmospheric CO 2 concentration. An asymptotic function showed a better fit of SOC and aggregation with CO 2 level than a linear model. There was a shift in allocation of total C from smaller size fractions to the largest aggregate fraction with increasing CO 2 concentration. Litter inputs appeared to be positively related to CO 2 concentration. Based on modeled function parameters and the observed shift in the allocation of the soil C from small to large aggregate‐size classes, we postulate that there is a hierarchy in C saturation across different SOC pools. We conclude that the asymptotic response of SOC concentration at higher CO 2 levels indicates saturation of soil C pools, likely because of a limit to physical protection of SOC.