Greenhouse gases emissions from riparian wetlands: an example from the Inner Mongolia grassland region in China

Gradual riparian wetland drying is increasingly sensitive to global warming and contributes to climate change. Riparian wetlands play a significant role in regulating carbon and nitrogen cycles. In this study, we analyzed the emissions of carbon dioxide (inline-formulaCO2), methane (inline-formulaCH4), and nitrous oxide (inline-formulaN2O) from riparian wetlands in the Xilin River basin to understand the role of these ecosystems in greenhouse gas (GHG) emissions. Moreover, the impact of the catchment hydrology and soil property variations on GHG emissions over time and space was evaluated. Our results demonstrate that riparian wetlands emit larger amounts of inline-formulaCO2 (335–2790 inline-formula $M5inlinescrollmathmlunit\mathrm{normal mg}\phantom{\rule{0ex}{0ex}}{\mathrm{normal m}}^{-normal 2}\phantom{\rule{0ex}{0ex}}{\mathrm{normal h}}^{-normal 1}$ 56pt15ptsvg-formulamathimg21fd9beb3b9b8119b6e5a3dce7b97099 bg-18-4855-2021-ie00001.svg56pt15ptbg-18-4855-2021-ie00001.png in the wet season and 72–387 inline-formula $M6inlinescrollmathmlunit\mathrm{normal mg}\phantom{\rule{0ex}{0ex}}{\mathrm{normal m}}^{-normal 2}\phantom{\rule{0ex}{0ex}}{\mathrm{normal h}}^{-normal 1}$ 56pt15ptsvg-formulamathimg2a5473a062b20eaf103feb361cb37799 bg-18-4855-2021-ie00002.svg56pt15ptbg-18-4855-2021-ie00002.png in the dry season) than inline-formulaCH4 and inline-formulaN2O to the atmosphere due to high plant and soil respiration. The results also reveal clear seasonal variations and spatial patterns along the transects in the longitudinal direction. inline-formulaN2O emissions showed a spatiotemporal pattern similar to that of inline-formulaCO2 emissions. Near-stream sites were the only sources of inline-formulaCH4 emissions, while the other sites served as sinks for these emissions. Soil moisture content and soil temperature were the essential factors controlling GHG emissions, and abundant aboveground biomass promoted the inline-formulaCO2, inline-formulaCH4, and inline-formulaN2O emissions. Moreover, compared to different types of grasslands, riparian wetlands were the potential hotspots of GHG emissions in the Inner Mongolian region. Degradation of downstream wetlands has reduced the soil carbon pool by approximately 60 %, decreased inline-formulaCO2 emissions by approximately 35 %, and converted the wetland from a inline-formulaCH4 and inline-formulaN2O source to a sink. Our study showed that anthropogenic activities have extensively changed the hydrological characteristics of the riparian wetlands and might accelerate carbon loss, which could further affect GHG emissions.

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Liu, Xinyu / Lu, Xixi / Yu, Ruihong / et al: Greenhouse gases emissions from riparian wetlands: an example from the Inner Mongolia grassland region in China. 2021. Copernicus Publications.

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