Methane Emissions Offset Net Carbon Dioxide Uptake From an Alpine Peatland on the Eastern Qinghai-Tibetan Plateau

Peatlands store large amounts of carbon (C) and actively exchange greenhouse gases (GHGs) with the atmosphere, thus significantly affecting global C cycle and climate. Large uncertainty exists in C and GHG estimates of the alpine peatlands on Qinghai-Tibetan Plateau (QTP), as direct measurements of CO₂ and CH₄ fluxes are scarce in this region. In this study, we provided 32-month CO₂ and CH₄ fluxes measured using the eddy covariance (EC) technique in a typical alpine peatland on the eastern QTP to estimate the net C and CO₂ equivalent (CO₂-eq) fluxes and investigate their environmental controls. Our results showed that the mean annual CO₂ and CH₄ fluxes were −68 ± 8 g CO₂-C m⁻² yr⁻¹ and 35 ± 0.3 g CH₄-C m⁻² yr⁻¹, respectively. While considering the traditional and sustained global warming potentials of CH₄ over the 100-year timescale, the peatland acted as a net CO₂-eq source (1,059 ± 30 and 1,853 ± 31 g CO₂-eq m⁻² yr⁻¹, respectively). The net CO₂-eq emissions during the non-growing seasons contributed to over 40% of the annual CO₂-eq budgets. We further found that net CO₂-eq flux was primarily influenced by global radiation and soil temperature variations. This study was the first assessment to quantify the net CO₂-eq flux of the alpine peatland in the QTP region using EC measurements. Our study highlights that CH₄ emissions from the alpine peatlands can largely offset the net cooling effect of CO₂ uptake and future climate changes such as global warming might further enhance their potential warming effect.