Quantification of Litter Fall and Estimation of Nutrient Release Through in-Situ Decomposition of Leaf Litter From Some Important Mangrove Species of Indian Sundarbans

Abstract Looking into the importance of mangrove leaf litter in regulation of sediment carbon sequestration and nutrient flux in Sundarbans ecosystem, an experiment was conducted at Jharkhali island of Sundarbans. In this experiment, collection of leaf litter-shedding from nine dominant mangrove species during December 2012 to November 2013 was donemonthly using ‘litter traps’ (1 m2) in Eco-garden on the bank of Herobhanga creek.Seasonal litter fall was highest in Geon (Excoecariaagallocha)(103 gm-2) followed by Keora (Sonneratiaapetala) (98.5 gm-2). Kal Bain (Avicennia alba) produced the highest amount (414.37 gm-2) of total annual leaf litter followed by Bruguieragymnorrhiza (410.43 gm-2). Kankra (Bruguieragymnorrhiza), Garjan (Rhizophoramucronata) and Geon (Excoecariaagallocha) dry leaf litters contained more than 50% carbon (oven dry basis). Litter from Avicennia group contained more nitrogen and carbon. Decomposition rates of various mangrove litters were estimated through twoshort-term (30 days and 52 days) in-situ experiments using mangrove leaf litter in nylon net bags (0.6 mm mesh) subjected to periodical diurnal submergence by tidalriver water at Jharkhali. During decomposition process,observation said thatmost susceptible and resistant litter with respect to mass loss were Geon (Excoecariaagallocha) (81±5.5%) and Taura (Aegialitisrotundifolia) (26±4%) respectivelyafter 30 days. The biomass retained after decomposition losses (average45±15.2%after 30 days and 56±20.2 % after 52 days) indicated the amount of carbon retained in mangrove soil and ultimately determines the carbon sequestered in soil through mangrove litter fall. The study gives important insight into contribution of different mangrove species in carbon sequestration and nutrient dynamics in mangrove ecosystem of Indian Sundarbans.