Quantifying landscape-level annual nitrous oxide fluxes in the Tibetan Plateau

Quantifying landscape nitrous oxide (N2O) fluxes and identifying how they are spatiotemporally controlled are critical for predicting N2O fluxes feedback to climate change and/or human disturbances. Here, we measured two-year N2O fluxes and environmental variables from a typical landscape in the Tibetan Plateau.

Annual N2O emissions showed large spatial variations (0.05–0.78 kg N ha–1 yr–1 from meadows to forest) which was significantly (p < 0.01) controlled by soil carbon-to-nitrogen ratios and dissolved organic carbon concentrations. Results also highlighted the importance of the non-growing seasons (particular soil freezethaw period) as they contributed 12–57% to annual fluxes.

Tibetan Plateau (TP, the ‘third pole’ of the earth), is a key region for studing climate change (Seddon et al., 2016). It has been observed that there existing a high spatial heterogenity in ecosystems types in this plateau (Chen et al., 2013). Therefore, one can postulate that N2O fluxes vary largely among ecosystems, as the high heterogenity in soil hydro-thermal conditions, soil properties, and microbial processess. However, there is a scaricity for this information in the TP. Accordingly, we initiated this study from a typical alpine landscape in the eastern TP, and we hypothesized that the magnitudes of soil N2O emissions increased with increasing soil moisture across ecosystems (i.e., from steppes to wetlands), and we also hypothesized that N2O emission during the non-growing season may contribute substantially to annual fluxes, as the long vegetation dormant period.