Open AccessN deposition and elevated CO 2 on methane emissions: Differential responses of indirect effects compared to direct effects through litter chemistry feedbacks
Author(s) -
Pancotto V. A.,
van Bodegom P. M.,
van Hal J.,
van Logtestijn R. S. P.,
Blokker P.,
Toet S.,
Aerts R.
Publication year - 2010
Publication title -
journal of geophysical research: biogeosciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2009jg001099
Subject(s) - litter , zoology , chemistry , plant litter , incubation , mineralization (soil science) , environmental chemistry , human fertilization , nitrogen , agronomy , nutrient , biology , biochemistry , organic chemistry
Increases in atmospheric CO 2 concentration and N deposition are expected to affect methane (CH 4 ) production in soils and emission to the atmosphere, directly through increased plant litter production and indirectly through changes in substrate quality. We examined how CH 4 emission responded to changes in litter quality under increased N and CO 2 , beyond differences in CH 4 resulting from changes in litter production. We used senesced leaves from 13 C‐labeled plants of Molinia caerulea grown at elevated and ambient CO 2 and affected by N fertilization to carry out two experiments: a laboratory litter incubation and a pot experiment. N fertilization increased N and decreased C concentrations in litter whereas elevated CO 2 decreased litter quality as reflected in litter C and N concentrations and in the composition of lignin and saturated fatty acids within the litter. In contrast to our expectations, CH 4 production in the laboratory incubation decreased when using litter from N‐fertilized plants as substrate, whereas litter from elevated CO 2 had no effect, compared to controls without N and at ambient CO 2 . Owing to high within‐treatment variability in CH 4 emissions, none of the treatment effects were reflected in the pot experiment. C mineralization rates were not affected by any of the treatments. The decrease in CH 4 emissions due to indirect effects of N availability through litter quality changes (described here for the first time) contrast direct effects of N fertilization on CH 4 production. The complex interaction of direct effects with indirect effects of increased N on litter quality may potentially result in a net decrease in CH 4 emissions from wetlands in the long term.