Soil methane emissions under the forest ecosystem of Chinese-fir and mixed broad-leaved forest

Abstract:

Abstract: To investigate the effects of different forest management practices on soil methane emissions, CH₄ fluxes was quantified with a static chamber-gas chromatography method under Chinese fir（Cunninghamia lanceolata） stands （CL）and mixed stands of Chinese fir and Cinnamomum cam-phora（CL-CC）, Castanopsis fargesii（CL-CF）, and Alnus cremastogyne（CL-AC）.Results showed that the traits of the methane emissions under four forest management practices are generally characterized by absorption, Castanopsis fargesii(-0.0314 mg·m ^-2·h^-1), Cinnamomum cam-phora(-0.0264 mg· m^{- 2}·h^-1), Alnus cremastogyne（ (-0.0230 mg·m ^-2·h^-1), and Cunninghamia lanceolata stands (-0.0220 mg·m^-2·h^-1), but forest management practices between soil CH₄ emission/uptake difference was not significant. Correlation analysis showed that soil CH₄ emissions were significantly correlated with nitrate nitrogen content and soil soluble nitrogen. Further regression analysis showed that soil nitrate nitrogen content and soil temperature were the main factors affecting soil CH₄ emissions. Soil net nitrogen mineralization rate and net ammonification rate were significantly correlated with soil CH₄ emission/absorption. Forest soils under all four management practices were an important sinks of atmospheric methane. In terms of reducing greenhouse gas emissions, Castanopsis fargesii（CL-CF） is superior to Cunninghamia lanceolata stands, Cinnamomum cam-phora（CL-CC）and Alnus cremastogyne（CL-AC）.

Key words: forest management; Soil carbon pool; Mixed forests; methane