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Transpiration alters the contribution of autotrophic and heterotrophic components of soil CO 2 efflux
Author(s) -
Grossiord Charlotte,
Mareschal Louis,
Epron Daniel
Publication year - 2012
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/j.1469-8137.2012.04102.x
Subject(s) - transpiration , soil respiration , autotroph , heterotroph , efflux , flux (metallurgy) , soil carbon , chemistry , xylem , respiration , environmental chemistry , environmental science , agronomy , botany , soil water , photosynthesis , soil science , biology , biochemistry , genetics , organic chemistry , bacteria
Summary• An unbiased partitioning of autotrophic and heterotrophic components of soil CO 2 efflux is important to estimate forest carbon budgets and soil carbon sequestration. The contribution of autotrophic sources to soil CO 2 efflux ( F A ) may be underestimated during the daytime as a result of internal transport of CO 2 produced by root respiration through the transpiration stream. • Here, we tested the hypothesis that carbon isotope composition of soil CO 2 efflux (δ FS ) in a Eucalyptus plantation grown on a C 4 soil is enriched during the daytime, which will indicate a decrease in F A during the periods of high transpiration. • Mean δ FS of soil CO 2 efflux decreased to −25.7‰ during the night and increased to −24.7‰ between 11:00 and 15:00 h when the xylem sap flux density was at its maximum. • Our results indicate a decrease in the contribution of root respiration to soil CO 2 efflux during the day that may be interpreted as a departure of root‐produced CO 2 in the transpiration stream, leading to a 17% underestimation of autotrophic contribution to soil CO 2 efflux on a daily timescale.