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Labile soil carbon inputs mediate the soil microbial community composition and plant residue decomposition rates
Author(s) -
de Graaff MarieAnne,
Classen Aimee T.,
Castro Hector F.,
Schadt Christopher W.
Publication year - 2010
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.1469-8137.2010.03427.x
Subject(s) - exudate , residue (chemistry) , chemistry , soil water , decomposition , incubation , respiration , microbial population biology , soil carbon , soil respiration , environmental chemistry , bacteria , botany , biology , biochemistry , ecology , organic chemistry , genetics
Summary• Root carbon (C) inputs may regulate decomposition rates in soil, and in this study we ask: how do labile C inputs regulate decomposition of plant residues, and soil microbial communities? • In a 14 d laboratory incubation, we added C compounds often found in root exudates in seven different concentrations (0, 0.7, 1.4, 3.6, 7.2, 14.4 and 21.7 mg C g −1 soil) to soils amended with and without 13 C‐labeled plant residue. We measured CO 2 respiration and shifts in relative fungal and bacterial rRNA gene copy numbers using quantitative polymerase chain reaction (qPCR). • Increased labile C input enhanced total C respiration, but only addition of C at low concentrations (0.7 mg C g −1 ) stimulated plant residue decomposition (+2%). Intermediate concentrations (1.4, 3.6 mg C g −1 ) had no impact on plant residue decomposition, while greater concentrations of C (> 7.2 mg C g −1 ) reduced decomposition (−50%). Concurrently, high exudate concentrations (> 3.6 mg C g −1 ) increased fungal and bacterial gene copy numbers, whereas low exudate concentrations (< 3.6 mg C g −1 ) increased metabolic activity rather than gene copy numbers. • These results underscore that labile soil C inputs can regulate decomposition of more recalcitrant soil C by controlling the activity and relative abundance of fungi and bacteria.