Salinity based allometric equations for biomass estimation of Sundarban mangroves

Biomass estimation was carried out for three even-aged dominant mangrove species (Avicennia alba, Excoecaria agallocha and Sonneratia apetala) in two regions of Indian Sundarbans with two distinct salinity regimes for three consecutive years (2008-2010) and the results were expressed in tons per hectare (t ha−1). In the western region, the total mean biomass of the mangrove species varied as per the order A. alba (41.65 t ha−1 in 2008, 55.79 t ha−1 in 2009, 60.86 t ha−1 in 2010) > S. apetala (31.76 t ha−1 in 2008, 32.81 t ha−1 in 2009, 39.10 t ha−1 in 2010) > E. agallocha (13.89 t ha−1 in 2008, 15.54 t ha−1 in 2009, 18.28 t ha−1 in 2010). In the central region, the order was A. alba (42.06 t ha−1 in 2008, 57.09 t ha−1 in 2009, 64.57 t ha−1 in 2010) > E. agallocha (15.30 t ha−1 in 2008, 20.02 t ha−1 in 2009, 24.24 t ha−1 in 2010) > S. apetala (6.77 t ha−1 in 2008, 9.46 t ha−1 in 2009, 11.42 t ha−1 in 2010). Significant negative correlation was observed between biomass of S. apetala and salinity (p < 0.01), whereas in case of A. alba and E. agallocha positive correlations were observed (p < 0.01). Species-wise linear allometric regression equations for biomass prediction were developed for each salinity zone as a function of diameter at breast height (DBH) based on high coefficient of determination (R2 value). The allometric models are species-specific, but not site-specific.