Fine Root Production and Its Benefaction to carbon storage of the Sundarbans Mangrove Forest

Abstract

The quantification of fine root production (FRP) and biomass (FRB) is of utmost importance in gaining insights into ecosystem dynamics. However, these aspects have received limited attention in mangrove forests, primarily due to the considerable time and labor required for accurate assessment. Therefore, our study aims to estimate FRP and FRB stocks in the Sundarbans mangrove forest in Bangladesh, specifically focusing on two distinct saline zones: oligohaline and mesohaline. To accomplish our objectives, we employed soil coring and long-term ingrowth core methods to collect soil samples from 20 study plots, each covering an area of 200 square meters. Additionally, we assessed the forest structure by measuring the tree height and diameter at breast height. Our findings revealed that the mean FRB and FRP across the study area were 12.65±1.12 Mgha-1 and 2.25±0.13 Mgha-1 y-1, respectively. Notably, the oligohaline zone, characterized by lower salinity levels, exhibited higher FRB stocks and FRP compared to the mesohaline zone. Furthermore, our analysis showed that FRP in the diameter class of 1-2 mm surpassed that of the 0.5-1 mm and ≤0.5 mm classes. In terms of biomass, the mean above-ground, below-ground, and total biomass carbon were determined to be 87.18 ± 18.3, 48.38 ± 8.0, and 135.57 ± 26.3 Mgha-1, respectively. Through species importance value (Iv) analysis, we identified Excoecaria agallocha as the dominant species in the oligohaline zone, while Sonneratia apetala exhibited the highest Iv value in the mesohaline area. Heritiera fomes emerged as the primary contributor to total biomass carbon, particularly in the oligohaline zone, whereas S. apetala contributed the most biomass carbon in the mesohaline zone. These findings emphasize the importance of protecting and conserving mangrove ecosystems as valuable contributors to global carbon dynamics due to its higher fine root production and its contribution to carbon stocks.