Carbon and nutrient dynamics in soil profile of different vegetation types of the Sundarbans, Bangladesh
Mangrove is the most productive ecosystem in the world. Sundarbans is the largest contiguous mangrove forest in the world located in the south-west of Bangladesh. The present study focused on the carbon and nutrient dynamics (N, P and K) of the Sundarbans. A total of 150 soil samples were collected from 30 sites of the Sundarbans using purposive stratified sampling that contains different vegetation types (pioneer species dominated sites and other than pioneer species) as well as different salinity zones (less saline, moderate and high saline). The organic carbon concentration in different layers was not varied significantly (p>0.05). The highest carbon concentration was detected for the top layer in both stands and lowest for the 80-100 cm depth in pioneer and 20-40 cm for the mature stand. In the case of Nitrogen, the mean nitrogen concentration among the layers and stands were not varied significantly (p>0.05). Comparatively higher nitrogen concentration was detected for 20-40 and 80-100 cm layers of pioneer stand and 0-20 cm for the mature stand. Comparatively higher phosphorus concentration was detected for 60-80 cm layers of pioneer stand; 40-60 and 80-100 cm depth for the mature stand. A higher concentration of Potassium was detected in 80-100 cm layers for both pioneer and mature stand. In the case of stocking, the higher stock was observed at the lowest layer (80-100 cm) for Carbon, Nitrogen, Phosphorus and Potassium. However, the stock of carbon, nitrogen, phosphorus and potassium showed significant positive relationship with the increasing depth of soil layers up to 1 m depth. The statistical models for the stock of carbon, nitrogen, phosphorus, and potassium were y = 1.2996x + 37.458, y = 15.455x0.0669, y = 10.696e0.0321x and y = 1.2139x + 16.829 respectively.