The age and species composition of mangrove forest directly influence the net primary productivity and carbon sequestration potential

Although mangroves inhabit only 0.7% of global coastal zone, but they have a significant contribution to the global carbon. Primary production by mangroves provides a substantial source of energy for aquatic food webs. Net primary productivity and carbon sequestration potential play a pivotal role in understanding the characteristics of the forest ecosystem. Therefore, in order to assess whether the age of mangrove forest and species composition has any influence on the net primary productivity and carbon sequestration potential; six plots of different age group (2, 7, 8, 12, 13 yrs and natural population), and mangrove species combinations were studied in Pichavaram mangrove forest, Tamil Nadu, India. Soil temperature, net canopy photosynthesis and forest functional index significantly varied between mangrove species and age. Regression analysis showed that the soil pH and bulk density positively influenced the carbon sequestration potential which was significant between age group. Higher age group (13yrs) and the natural site showed two-fold higher (21.52 +/- 0.72 gC/m(2)/day) net canopy photosynthesis. Forest functional index, shoot Biomass, root Biomass, plant biomass, carbon biomass and CO2 equivalent showed significant variation with species or age having maximum value in natural plot. Net primary productivity was significant between mangrove species or age. However, carbon sequestration potential increased with the increase in age of plants. Maximum carbon sequestration potential was found in Xylocarpus mekongensis. The data obtained from the present study can be effectively used for drafting conservation and management policies for the fragile mangrove forest ecosystem.