Bryophytes impact the fluxes of soil non-carbon dioxide greenhouse gases in a subalpine coniferous forest

Abstract

Terrestrial bryophytes substantially regulate ecosystem processes in high latitude and high elevation ecosystems; however, the role of these plants in mediating soil emissions of non-CO2 greenhouse gases (GHGs) (N2O and CH4) in these ecosystems remains poorly understood. A removal experiment was conducted to investigate the influence of bryophytes on soil non-CO2 GHGs emission in a subalpine coniferous forest on the eastern edge of the Tibetan Plateau. Bryophyte removal decreased the average N2O emission rate, but did not significantly alter the CH4 flux rate. The cumulative amount of N2O emission and CH4 uptake was decreased by bryophyte removal. Compared to bryophyte-removal plots, soil in the control plots had higher concentrations of soil organic C (SOC), total N (TN), dissolved organic C (DOC), dissolved N (DN), and exchangeable NH4+. The control plots also had higher cumulative N2O emission and CH4 uptake compared to plots with bryophytes removed. Bryophyte-removal significantly changed the relationship between soil non-CO2 GHGs flux rates and soil water content, induced a linear decreasing relationship between the N2O emission rate and soil water content and a quadratic relationship between CH4 flux rate and soil water content in the bryophyte-removal plots. Results from this study indicate that bryophytes may regulate non-GHG emissions from subalpine coniferous soils and demonstrate that in the presence of bryophytes, these soils may act as a greater N2O source and CH4 sink in southwestern China.