Biomass accumulation in a rehabilitated mangrove forest at Gazi Bay

Abstract

Estimation of biomass in woody ecosystems is important because of its role in wood yield determination, relevance to nutrient turnover, and the potential to store carbon. Most studies on mangrove biomass have over the years tended to concentrate on standing biomass with very little on below-ground biomass. The present study estimates total above and below ground biomass in mangroves. Allometric relations were developed relating biomass with easily measurable parameters in a young six-years Rhizophora mucronata plantation established in 2001 in an originally El Nino impacted site at Gazi Bay. Twelve isolated trees were sampled using destructive method. The stem diameters were measured at first branching (DB) and diameter at 30 cm from the highest prop root (D sub(30)). Total above-ground biomass gave the best fit (r2=0.97) when regressed against the independent variable D302H. There was a clear correlation between below-ground biomass (BGB) and D30(30) 2H (r2=0.98). The best estimator for total biomass gave the best fit when regressed against D302H (r2=0.98) using the equation B total (g dry weight) =2.0095 x D302H (cm2) + 1463.1. Overall, above-ground biomass and below ground biomass accounted for 63-82% and 18-37% of the total dry weight respectively. Allometric equations developed in this study provide a useful tool of estimating total biomass in replanted mangroves and hence improve on forest management.