Precipitation Controls on Carbon Sinks in an Artificial Green Space in the Taklimakan Desert

Control of desertification can not only ameliorate the natural environment of arid regions but also convert desertified land into significant terrestrial carbon sinks, thereby bolstering the carbon sequestration capacity of arid ecosystems. However, longstanding neglect of the potential carbon sink benefits of desertification management, and its relationship with environmental factors, has limited the exploration of carbon sequestration potential. Based on CO₂ flux and environmental factors of artificial protective forest in the Taklamakan Desert from 2018 to 2019, we found that the carbon storage capacity of the desert ecosystem increased approximately 140-fold after the establishment of an artificial shelter forest in the desert, due to plant photosynthesis. Precipitation levels less than 2 mm had no impact on carbon exchange in the artificial shelter forest, whereas a precipitation level of approximately 4 mm stimulated a decrease in the vapor pressure deficit over a short period of about three days, promoting photosynthesis and enhancing the carbon absorption of the artificial shelter forest. Precipitation events greater than 8 mm stimulated soil respiration to release CO₂ and promoted plant photosynthesis. In the dynamic equilibrium where precipitation stimulates both soil respiration and photosynthesis, there is a significant threshold value of soil moisture at 5 cm (0.12 m³ m⁻³), which can serve as a good indicator of the strength of the stimulatory effect of precipitation on both. These results provide important data support for quantifying the contribution of artificial afforestation to carbon sequestration in arid areas, and provide guidance for the development and implementation of artificial forest management measures.