Preprints
https://doi.org/10.5194/egusphere-2024-1226
https://doi.org/10.5194/egusphere-2024-1226
01 Jul 2024
 | 01 Jul 2024
Status: this preprint is open for discussion.

CO2 flux characteristics of the grassland ecosystem and its response to environmental factors in the dry-hot valley of Jinsha River, China

Chaolei Yang, Yufeng Tian, Jingqi Cui, Guangxiong He, Jingyuan Li, Canfeng Li, Haichuang Duan, Zong Wei, Liu Yan, Xin Xia, Yong Huang, and Aihua Jiang

Abstract. The dry-hot valley of Jinsha River is distinguished by prolonged drought and high temperatures, making it a distinct non-zonal hot island habitat in the global temperate zone. It is an ideal location for studying changes in plant carbon budget under sustained drought and high-temperature conditions. However, there is currently a dearth of reports on CO2 flux variations within plant ecosystems in this region. The study quantitatively analyzed the characteristics of CO2 flux variation in the grassland ecosystem in this region and its response mechanisms to environmental factors using continuous observation data obtained from static assimilative chamber. The results indicate that both the environmental factors and CO2 flux variations in grassland ecosystems exhibit significant seasonal characteristics. During the dry season (March to May), the grassland acts as a carbon source, exhibiting a daily average CO2 flux of 0.1632 μmol·m-2·s-1, which cumulative CO2 emissions for each month were 18.64 g·m-2, 15.96 g·m-2, and 20.64 g·m-2, respectively. The ecosystem showed noteworthy carbon absorption characteristics during the rainy season (August to October), with a daily average CO2 flux of -0.1062 μmol·m-2·s-1, which cumulative CO2 absorption for each month were 6.42 g·m-2, 24.41 g·m-2, and 5.14 g·m-2, respectively. Throughout the year, the ecosystem was a weak carbon source, emitting an annual cumulative CO2 of 0.7078 t·ha-1·a-1, demonstrating carbon-neutral traits. In terms of environmental factors, there was a robust negative correlation exists with CO2 flux between photosynthetically active radiation during the rainy season (R= -0.578, P<0.01). The daily CO2 flux in different seasons was positively correlated with precipitation and relative humidity (P<0.01), and negatively correlated with air temperature, soil temperature and vapor pressure deficit (P<0.01). The diurnal variation of CO2 flux in dry season was mainly affected by relative humidity, while that in rainy season was mainly affected by relative humidity and vapor pressure deficit. The variation of CO2 flux was most influenced by soil water content, relative humidity, and vapor pressure deficit at both daily and monthly scales throughout the year. The influence of temperature factor on CO2 flux changes at different time scales is generally weak.

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Chaolei Yang, Yufeng Tian, Jingqi Cui, Guangxiong He, Jingyuan Li, Canfeng Li, Haichuang Duan, Zong Wei, Liu Yan, Xin Xia, Yong Huang, and Aihua Jiang

Status: open (until 12 Aug 2024)

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Chaolei Yang, Yufeng Tian, Jingqi Cui, Guangxiong He, Jingyuan Li, Canfeng Li, Haichuang Duan, Zong Wei, Liu Yan, Xin Xia, Yong Huang, and Aihua Jiang
Chaolei Yang, Yufeng Tian, Jingqi Cui, Guangxiong He, Jingyuan Li, Canfeng Li, Haichuang Duan, Zong Wei, Liu Yan, Xin Xia, Yong Huang, and Aihua Jiang

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Short summary
The environmental factors and CO2 flux of the grassland ecosystem in the dry-hot valley of the Jinsha River exhibited highly seasonal characteristics. During the rainy season, the grassland showed a carbon sink feature, while during the dry season, it exhibited carbon emission status. Throughout the entire year, the grassland ecosystem acted as a weak carbon source, exhibiting a carbon-neutral. The CO2 flux was most influenced by vapor pressure deficit, relative humidity, and soil water content.