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



Publication Details
Authors:
Xu, Y.; Fan, J.; Ding, W.; Gunina, A.; Chen, Z.; Bol, R.; Luo, J.; Bolan, N.
Publisher:
ELSEVIER SCIENCE BV
Publication year:
2017
Journal:
Geoderma
Pages range:
116-124
Volume number:
286
Start page:
116
End page:
124
Number of pages:
9
ISSN:
0016-7061

Abstract
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.


Keywords
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