Carbon and nitrogen pools in a mangrove stand of Kandelia obovata (S., L.) Yong: Vertical distribution in the soil-vegetation system

Attempts were made to quantify the carbon and nitrogen pools in a monospecific and pioneer mangrove stand of Kandelia obovata Sheue, Liu & Yong, Okinawa Island, Japan. The leaf C and N concentrations on a leaf area basis decreased with increasing PPFD (Photosysthetic Photon Flux Density). The total C and N stocks in foliage were estimated as 3.55 Mg ha-1 and 0.105 Mg ha-1, respectively. The bark (45.6-48.6% for C and 0.564-0.842% for N) contained significantly higher amount of C (P < 0.05) and N (P < 0.01) than wood (46.2-47.8% for C and 0.347-0.914% N). The total C stock of stem was 23.2 Mg ha-1 in wood and 8.33 Mg ha-1 in bark, and the total N stock was 0.222 Mg ha-1 in wood and 0.116 Mg ha-1 in bark. The root wood (37.1-45.0%) contained significantly higher amount of C than root bark (35.4-40.7%) (P < 0.01). The total C stock of root was 14.2 Mg ha-1 in wood and 12.6 Mg ha-1 in bark, and the total N stock of root was 0.157 Mg ha-1 in wood and 0.155 Mg ha-1 in bark. The soil organic C and total N stocks within 1 m soil depth were estimated as 57.3 Mg ha-1 and 2.73 Mg ha-1, respectively. The C pool in aboveground biomass (35.1 Mg ha-1) was 1.3 times as large as that in belowground biomass (26.9 Mg ha-1). However, the soil organic C pool (57.3 Mg ha-1) was similar to the total C pool (62.0 Mg ha-1) of vegetation, indicating that the mangrove stored a large part of production in the soil. About 50% of the C was in the soil. The N pool in aboveground biomass (0.442 Mg ha-1) was 1.4 times as large as that in belowground biomass (0.312 Mg ha-1). The soil N stock was 3.3 times as large as the biomass N stock (0.754 Mg ha -1). © 2006 Springer Science+Business Media, Inc.