Study on Distribution of Sediment Carbon and Nitrogen in Laguncularia racemosa Artificial Forest Wetland of Jiulong River Estuary, Fujian Province

This study analyzed the variations and distribution characteristics of TOC and TN contents of the sediments of Laguncularia racemosa artificial forest in Jiulong River estuary, Fujian Province. Three sampling zones were set up in each forest: the seaward forest margin, forest center, and landward forest margin. Soil samples were collected from depths of 0–10, 10–20, and 20–40 cm at each sampling point, totaling 108 samples. The results showed that: (1) The TOC content was higher in autumn than in winter, and the 12-year L. racemosa forests was higher than the 8-year. As soil depth increased, the overall TOC content showed a decreasing trend. The TOC content at the seaward forest margin was lower than forest center and the landward forest margin. The TOC content in the sediments of L. racemosa forests ranged from 13.05  to  28.18 g/kg, showing a strong TOC storage ability of L. racemosa forests. (2) The TN content in the sediments of L. racemosa forests varied between 1.59  and  2.60 g/kg. The vertical distribution of TN showed no consistent pattern. The TN content at landward forest margin was less than seaward forest margin and forest center. (3) The coefficient of variation for TOC content in the sediments at different depths in L. racemosa forests was consistently higher than that for TN content. This suggested that the horizontal distribution of TN content was less influenced by L. racemosa forests than TOC content.