Characterizing the post-monsoon CO_2, CH_4, N_2O, and H_2O vapor fluxes from a tropical wetland in the Himalayan foothill

摘要

Wetlands are emitters of greenhouse gases. However, many of the wetlands remain understudied (like temperate, boreal, and high-altitude wetlands), which constrains the global budgets. Himalayan foothill is one such data-deficient area. The present study reported (for the first time) the greenhouse gas fluxes (CO2, CH4, N2O, and H2O vapor) from the soils of the Nakraunda wetland of Uttarakhand in India during the post-monsoon season (October 2020 to January 2021). The sampling points covered six different types of soil within the wetlands. CO2, CH4, N2O, and H2O vapor emissions ranged from 82.89 to 1052.13 mg m(-2) h(-1), 0.56 to 2.25 mg m(-2) h(-1), 0.18 to 0.40 mg m(-2) h(-1), and 557.96 to 29,397.18 mg m(-2) h(-1), respectively, during the study period. Except for CO2, the other three greenhouse gas effluxes did not show any spatial variability. Soils close to "swamp proper" emitted substantially higher CO2 than the vegetated soils. Soil temperature exhibited exponential relationships with all the greenhouse gas fluxes, except for H2O vapor. The Q(10) values for CO2, CH4, and N2O varied from 3.42 to 4.90, 1.66 to 2.20, and 1.20 to 1.30, respectively. Soil moisture showed positive relationships with all the greenhouse gas fluxes, except for N2O. The fluxes observed from Nakraunda were in parity with global observations. However, this study showed that wetlands experiencing lower temperature regime are also capable of emitting a substantial amount of greenhouse gases and thus, requires more study. Considering the seasonality of greenhouse gas fluxes should improve global wetland emission budgets.