Effects of rainfall amount and frequency on carbon exchange in a wet meadow ecosystem on the Qinghai-Tibet Plateau

• Published in: Catena (Giessen) Vol. 219; p. 106629
• Main Authors: Wu, Jiangqi, Wang, Haiyan, Li, Guang, Lu, Yanhua, Wei, Xingxing
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.12.2022
• Subjects: Ecosystem CO2 exchange; Extreme rainfall pattern; Qinghai-Tibet Plateau; Soil carbon components; Soil properties; Wet Meadow; Ecosystem CO2 exchange; Wet Meadow; Qinghai-Tibet Plateau; Soil properties; Extreme rainfall pattern; Soil carbon components
• ISSN: 0341-8162; 1872-6887
• DOI: 10.1016/j.catena.2022.106629

•High-frequency extreme rainfall promotes the carbon sink function of wet meadows.•Increase in extreme rainfall frequency affects soil properties and promotes CO2 absorption.•The increase in extreme rainfall frequency increases aboveground net primary productivity.•The increase in extreme rainfall frequency decreases soil bulk density.•The CO2 flux was affected by soil carbon components under different extreme rainfall frequency. Extreme rainfall amount and frequency can alter carbon dioxide (CO2) exchange between the soil and vegetation in wetlands. Seasonal redistribution of extreme rainfall events is one component of a hydrological regime that affects soil water content (SWC), but its impacts on ecosystem CO2 exchange in the Qinghai-Tibet Plateau (QTP) wetlands remain unclear. Here, we conducted field simulation experiments to understand the effects of extreme rainfall with high to low frequency once every-one, two, three, and four weeks on CO2 exchange of wet meadow ecosystem in QTP. The ecosystem absorbed more CO2 with high-frequency extreme rainfall (−1468.52 mg C m-2h−1) than with current natural amounts and frequency of rainfall (−1162.51 mg C m-2h−1) throughout local vegetation growing seasons. However, under low-frequency extreme rainfall (−916.72 mg C m-2h−1) the wetland absorbed less CO2 than under natural rainfall frequency. This difference comes from the changes in net ecosystem productivity (NEP) and ecosystem respiration (ER) in wet meadows due to soil temperature (ST) and soil nutrient content. In the rapid growth stage of plants, ER and NEP exhibited single-peak curves due to increases in ST and SWC, and they reached their maximum values in August. Our results indicate that the distribution pattern of extreme rainfall events plays a critical role in regulating ecosystem CO2 exchange in the wet meadows of the QTP. More research on the related changes between contents of soil nutrient contents and extreme rainfall events could improve the accuracy of C budget estimation in wet meadows. The predicted regional impacts of future climate extremes of rainfall will rely on changes in their frequency and timing.