Data on investigation of Carbon Dynamics Regulated by Microorganisms in Mangrove Wetlands of Hainan, China

This study conducted an experiment on exogenous nitrogen input carried by tidal action in coastal wetlands from August 1, 2023 to January 27, 2024, aiming to investigate the impact of nitrogen input in coastal wetlands on soil carbon dynamics and the microbial mechanisms underlying the changes in carbon dynamics. The experiment lasted for 180 days. Before the experiment, in-situ soil samples and microbial samples were collected to determine the baseline values of soil properties and soil microorganisms (Pre). Meanwhile, the plant height and diameter were measured before the experiment. The soil testing indicators included TN (Total Nitrogen), TC (Total Carbon), TOC (Total Organic Carbon), DOC (Dissolved Organic Carbon), NH₄⁺-N (Ammonium Nitrogen), NO₃-N (Ammonia Nitrogen), pH, and moisture content. After the experiment started, soil samples were collected and tested every 15 days, and the concentrations of CO₂ and CH₄ gases were measured. The ambient temperature during gas measurement was recorded, and the fluxes of CO₂ and CH₄ were obtained through calculation. At the end of the experiment (180 days), data such as plant height and stem diameter were measured again. Meanwhile, microbial samples were collected, and 16S DNA data and functional gene data were obtained through testing. These data were used to monitor changes in soil properties, variations in CO₂ and CH₄ fluxes, and changes in microbial community structure under the condition of exogenous nitrogen input, so as to study the influencing factors of CO₂ and CH₄ emissions, the influencing factors of DOC concentration changes, and the microbial mechanisms of carbon dynamic changes under nitrogen input conditions.
The results showed that the release of carbon into the environment in this study mainly came from soil CO₂ emissions and DOC loss. The simulated tidal action caused a large amount of DOC loss, which was the main factor for DOC loss in mangrove wetland soils. The threshold value of nitrogen addition for the transformation effects on soil nutrients (TN, NO₃⁻-N), soil carbon storage (TC, TOC) and plant biomass in mangrove wetlands was 2 (mg/L). Salinity, NH₄⁺-N, and changes in DOC are the key soil components that drive variations in the abundance of microbial functional genes. Nitrogen input increased the abundances of carbon-degrading genes such as amyA, pgu, glx, chiA, and apu, promoted the carbon degradation process, and the production of more substrates led to an increase in CO₂ emissions.