Journal article
Characterization of organic carbon in decomposing litter exposed to nitrogen and sulfur additions: Links to microbial community composition and activity

Publication Details
Xu, Y.; Fan, J.; Ding, W.; Gunina, A.; Chen, Z.; Bol, R.; Luo, J.; Bolan, N.
Publication year:
Pages range:
Volume number:
Start page:
End page:
Number of pages:

Understanding the links between litter chemical transformations and functional microbial communities is key to elucidating the mechanisms of litter decompotition processes under nitrogen (N) and sulfur (S) deposition. Carbon (C)-13-labelled Pinus massoniana needles were incubated in a subtropical plantation forest soil exposed to: no amendment (Control), N amendments of 81 (N1) and 270 (N2) mg kg(-1), S amendments of 121 (S1) and 405 (S2) mg kg-1 and combined N and S amendments. Litter decomposition was measured as litter-derived carbon dioxide (CO2) emissions and the litter C pools were partitioned using a two-pool model. Relationships between litter residue chemistry (assessed by C-13 nuclear magnetic resonance spectroscopy analysis) and microbial community composition (probed by phospholipid fatty acid analysis, PLFA) and activity (the metabolic quotient, qCO(2)) were investigated. Over the 420 days incubation period, N and S additions (except N and S addition alone at low rate) significantly increased litter decomposition by 72-18.9% compared to the Control. Decomposition was stimulated by 10.2-61.9% during the"initial 56 days (stage 1) and in contrast, 83-42.1% inhibition was measured during 57-420 days (stage 2) across the addition treatments. Stimulation on litter-derived CO2 emissions under the N and S additions was largely dependent on the loss of O-alkyl C, a dominant component of the litter active C pool. During the initial 7 days, N and S additions increased the ratio of fungal to bacterial PLFAs compared to the Control, which was accompanied by the increases in methoxyl C. The activity of microbes, particularly gram-negative bacteria, was also increased by N and S additions at stage 1, which was related to di-O-alkyl C. In contrast, fungal activity decreased under N and S additions at stage 2, accompanied by lowered C availability and increased methoxyl C. Alkyl C and aromatic C in the litter had positive relationships with the half-life of the slow C pool. Accordingly, the residue recalcitrance was increased under N and S additions compared with Control at stage 2, and was largely responsible for the inhibition of litter" decomposition. Thus, N and S deposition is likely to increase the persistence of litter-derived recalcitrant C in subtropical forest soils in the long term. (C) 2016 Elsevier B.V. All rights reserved.

Litter C pools, Litter decomposition, Microbial activity, N and S deposition, PLFA, Solid-state C-13 NMR

Last updated on 2019-25-07 at 16:10