Effects of the Coastal Mangrove Restoration on the Soil Carbon, Nitrogen and Phosphorus Content and Stoichiometric Characteristics

In order to explore the effect of mangrove restoration on the soil carbon, nitrogen and phosphorus contents, the artificial mangrove wetland, natural mangrove wetland and aquaculture tidal flat in Fuding City were selected as the research objects, and the in-situ and laboratory analysis was carried out to explore the effect of mangrove restoration on the soil nutrient dynamics. The results showed that: (1) Compared with the natural mangrove wetlands, the restoration of artificial mangrove increased the soil nitrogen and phosphorus contents, and its carbon content of soil also returned to the level in the natural mangrove wetlands. (2) Among different wetland types, the carbon and phosphorus storage of soil in the aquaculture tidal flats were the highest. Compared with the natural mangrove wetland, the restoration of artificial mangrove increased the soil nitrogen and phosphorus storage. (3) The ratio of carbon, nitrogen and phosphorus in soil among different wetland types generally followed the pattern: carbon-phosphorus ratio＞carbon-nitrogen ratio＞nitrogen-phosphorous ratio. The carbon-nitrogen ratio of soil was the highest in the aquaculture tidal flats, followed by the natural mangroves and artificial mangroves. The carbon-phosphorus ratio and nitrogen-phosphorous ratio of soil were the highest in the natural mangroves, followed by the artificial mangroves and aquaculture tidal flats. The studies have shown that with the restoration of mangroves, their ecological functions have gradually returned to the level of natural mangroves, but their carbon storage was not much better than that of aquaculture tidal flats. In the future, the longer time-scale observation and research should be carried out to clarify the process and mechanism of mangrove restoration in regulating the soil carbon and nutrient dynamics.