Variations in CO<sub>2</sub> and CH<sub>4</sub> Exchange in Response to Multiple Biophysical Factors from a Mangrove Wetland Park in Southeastern China
Mangrove ecosystems can be both significant sources and sinks of greenhouse gases. The restoration of mangrove forests is increasingly used as a natural climate solution tool to mitigate climate change. However, the estimates of carbon exchanges remain unclear, especially from restored mangroves. In...
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MDPI AG
2023-04-01
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| Online Access: | https://www.mdpi.com/2073-4433/14/5/805 |
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| author | Chunlin Wang Xiaosong Zhao Xianyan Chen Chan Xiao Xingwang Fan Chong Shen Ming Sun Ziqi Shen Qiang Zhang |
| author_facet | Chunlin Wang Xiaosong Zhao Xianyan Chen Chan Xiao Xingwang Fan Chong Shen Ming Sun Ziqi Shen Qiang Zhang |
| author_sort | Chunlin Wang |
| collection | DOAJ |
| description | Mangrove ecosystems can be both significant sources and sinks of greenhouse gases. The restoration of mangrove forests is increasingly used as a natural climate solution tool to mitigate climate change. However, the estimates of carbon exchanges remain unclear, especially from restored mangroves. In this study, we observed the temporal variations in carbon dioxide (CO<sub>2</sub>) and methane (CH<sub>4</sub>) fluxes and their biophysical controls for 4 years, based on a closed-path eddy covariance (EC) system. The measurements were conducted in a mangrove wetland park with 14-year-old restored mangroves surrounded by open waters in Guangdong Province, China. The EC measurements showed that the mangrove ecosystem acted as a CO<sub>2</sub> source with a net CO<sub>2</sub> ecosystem exchange (NEE) of 305 g C m<sup>−2</sup> from January 2019 to May 2020 by the 5-m tower measurement. After the tower was adjusted to 10 m, the mangrove showed a CO<sub>2</sub> sink with an NEE of −345 g C m<sup>−2</sup> from June 2020 to December 2022. The change in tower height influenced the interpretation of interannual trends on NEE. There were no significant interannual trends in the gross primary productivity (GPP) and the ecosystem respiration (Re) values. The change from CO<sub>2</sub> source to sink may be attributed to the decrease in land surface proportion by the tower replacement, which reduces the proportion of the mangrove canopy respiration and, therefore, captures lower CO<sub>2</sub> fluxes from open waters. The restored mangroves indicated strong CH<sub>4</sub> sources of 23.2–26.3 g C m<sup>−2</sup> a<sup>−1</sup>. According to the random forest analysis, the land surface proportion, radiation, and relative humidity were the three most important predictors of NEE, while the CH<sub>4</sub> flux was most sensitive to air temperature. Compared to the natural and long-term restored mangroves, this 14-year-old restored mangrove had not yet achieved a maximum carbon sequestration capability. Our study highlights the need for the careful design of long-term observations from restored mangroves and proposes future needs in the context of carbon neutrality. |
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| language | English |
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| spelling | doaj.art-13566eef0062445ab7cd3cc78b63c6bf2023-11-18T00:25:06ZengMDPI AGAtmosphere2073-44332023-04-0114580510.3390/atmos14050805Variations in CO<sub>2</sub> and CH<sub>4</sub> Exchange in Response to Multiple Biophysical Factors from a Mangrove Wetland Park in Southeastern ChinaChunlin Wang0Xiaosong Zhao1Xianyan Chen2Chan Xiao3Xingwang Fan4Chong Shen5Ming Sun6Ziqi Shen7Qiang Zhang8Guangzhou Climate and Agrometeorology Center, Guangzhou 510080, ChinaSouthern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai 519000, ChinaNational Climate Center, China Meteorological Administration, Beijing 100081, ChinaNational Climate Center, China Meteorological Administration, Beijing 100081, ChinaKey Laboratory of Watershed Geographic Sciences, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, ChinaGuangzhou Climate and Agrometeorology Center, Guangzhou 510080, ChinaGuangxi Institute of Meteorological Sciences, Nanning 530022, ChinaGuangzhou Climate and Agrometeorology Center, Guangzhou 510080, ChinaNational Climate Center, China Meteorological Administration, Beijing 100081, ChinaMangrove ecosystems can be both significant sources and sinks of greenhouse gases. The restoration of mangrove forests is increasingly used as a natural climate solution tool to mitigate climate change. However, the estimates of carbon exchanges remain unclear, especially from restored mangroves. In this study, we observed the temporal variations in carbon dioxide (CO<sub>2</sub>) and methane (CH<sub>4</sub>) fluxes and their biophysical controls for 4 years, based on a closed-path eddy covariance (EC) system. The measurements were conducted in a mangrove wetland park with 14-year-old restored mangroves surrounded by open waters in Guangdong Province, China. The EC measurements showed that the mangrove ecosystem acted as a CO<sub>2</sub> source with a net CO<sub>2</sub> ecosystem exchange (NEE) of 305 g C m<sup>−2</sup> from January 2019 to May 2020 by the 5-m tower measurement. After the tower was adjusted to 10 m, the mangrove showed a CO<sub>2</sub> sink with an NEE of −345 g C m<sup>−2</sup> from June 2020 to December 2022. The change in tower height influenced the interpretation of interannual trends on NEE. There were no significant interannual trends in the gross primary productivity (GPP) and the ecosystem respiration (Re) values. The change from CO<sub>2</sub> source to sink may be attributed to the decrease in land surface proportion by the tower replacement, which reduces the proportion of the mangrove canopy respiration and, therefore, captures lower CO<sub>2</sub> fluxes from open waters. The restored mangroves indicated strong CH<sub>4</sub> sources of 23.2–26.3 g C m<sup>−2</sup> a<sup>−1</sup>. According to the random forest analysis, the land surface proportion, radiation, and relative humidity were the three most important predictors of NEE, while the CH<sub>4</sub> flux was most sensitive to air temperature. Compared to the natural and long-term restored mangroves, this 14-year-old restored mangrove had not yet achieved a maximum carbon sequestration capability. Our study highlights the need for the careful design of long-term observations from restored mangroves and proposes future needs in the context of carbon neutrality.https://www.mdpi.com/2073-4433/14/5/805carbon dioxidemethanemangrove restorationSoutheast Chinaeddy covariance |
| spellingShingle | Chunlin Wang Xiaosong Zhao Xianyan Chen Chan Xiao Xingwang Fan Chong Shen Ming Sun Ziqi Shen Qiang Zhang Variations in CO<sub>2</sub> and CH<sub>4</sub> Exchange in Response to Multiple Biophysical Factors from a Mangrove Wetland Park in Southeastern China Atmosphere carbon dioxide methane mangrove restoration Southeast China eddy covariance |
| title | Variations in CO<sub>2</sub> and CH<sub>4</sub> Exchange in Response to Multiple Biophysical Factors from a Mangrove Wetland Park in Southeastern China |
| title_full | Variations in CO<sub>2</sub> and CH<sub>4</sub> Exchange in Response to Multiple Biophysical Factors from a Mangrove Wetland Park in Southeastern China |
| title_fullStr | Variations in CO<sub>2</sub> and CH<sub>4</sub> Exchange in Response to Multiple Biophysical Factors from a Mangrove Wetland Park in Southeastern China |
| title_full_unstemmed | Variations in CO<sub>2</sub> and CH<sub>4</sub> Exchange in Response to Multiple Biophysical Factors from a Mangrove Wetland Park in Southeastern China |
| title_short | Variations in CO<sub>2</sub> and CH<sub>4</sub> Exchange in Response to Multiple Biophysical Factors from a Mangrove Wetland Park in Southeastern China |
| title_sort | variations in co sub 2 sub and ch sub 4 sub exchange in response to multiple biophysical factors from a mangrove wetland park in southeastern china |
| topic | carbon dioxide methane mangrove restoration Southeast China eddy covariance |
| url | https://www.mdpi.com/2073-4433/14/5/805 |
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