Seasonal variations of soil respiration and its effect on blue carbon sink function in the restored mangrove wetland in southern Zhejiang province

Soil respiration (R_soil) is the largest source of carbon dioxide (CO₂) released from ecosystems to the atmosphere, and small changes in R_soil have a great impact on mangrove wetland carbon sequestration. Based on the data of R_soil and correlative environmental factors monitored monthly in the restored mangrove wetland in south Zhejiang throughout 2021, we explored the seasonal variations of R_soil and its contribution to ecosystem respiration (R_eco), and the influence of R_soil on carbon sequestration ability. The results showed that the R_soil of the mangrove wetland had obvious seasonal variations and reached the peak in summer. The key environmental drivers of R_soil were soil temperature (T_S) and soil humidity (W_S), the combined effects of T_S and W_S could explain 84.6% changes in R_soil. Though R_soil was the main contributor to R_eco in the restored mangroves wetland, the annual average value of R_soil(0.69±0.54) µmol/(m²·s)was lower than that of other coastal wetlands. R_soil increased gradually with stand age, but the increasing degree of R_soil was considerably lower than that of net ecosystem CO₂ exchange (NEE), indicating that the restored mangrove was conducive to the coastal blue carbon. The results will be beneficial to deepen the understanding of the change characteristics of R_soil and carbon budget in order to accurately evaluate carbon neutralization potential of mangroves wetlands in southern Zhejiang province.