Response of net ecosystem CO2 exchange to precipitation events in the Badain Jaran Desert

It is of great significance to study the effects of precipitation events on carbon exchange in the ecosystem for an accurate understanding of the carbon cycle. However, the response of net ecosystem CO2 exchange (NEE) in the desert to precipitation events is elusive. In this study, the NEE in response to precipitation events of varying intensities in the Badain Jaran Desert (BJD) in China was continuously monitored using the eddy covariance (EC) technique. The following results were obtained: (1) The BJD ecosystem was a net CO2 sink throughout the study period, with NEE values of -113.4, -130.7, and -175.4 g C m(-2)a(-1) in 2016, 2018, and 2019, respectively. The total precipitation yielded a higher carbon sequestration capacity in 2019 than in the other two years. In addition, the intensity, time, and frequency of precipitation had significant impacts on CO2; (2) the threshold value of the NEE response to precipitation was similar to 1.4 mm, indicating the extreme sensitivity of the BJD to precipitation events; (3) the variations in the NEE response to precipitation events conformed to a dual exponential model. The analytical results of the model indicate that precipitation intensity was positively correlated with the carbon sequestration capacity of the desert. The model revealed that the greater the precipitation intensity, the longer it takes the NEE to reach the maximum, and the lengthier the duration of the residual effects. With an increase in the total precipitation and frequency of extreme precipitation events under warm and humidification climates, the carbon sequestration capacity of the BJD will likely be enhanced. The results of this study are of great significance for revealing the carbon cycle mechanism of the desert ecosystem.

Automated summary

Studying the effects of precipitation events on carbon exchange in the ecosystem is crucial for understanding the carbon cycle. This study continuously monitored the net ecosystem CO2 exchange (NEE) in response to varying intensity precipitation events in the Badain Jaran Desert in China. The results showed that precipitation intensity, time, and frequency had significant impacts on CO2, with the desert being highly sensitive to precipitation events. Higher precipitation intensity led to increased carbon sequestration capacity in the desert. With increased total precipitation and frequency of extreme precipitation events under warm and humid climates, the carbon sequestration capacity of the desert is expected to enhance.