Above and below ground carbon stock assessment of natural and planted mangrove forest in Davao Occidental, Philippines

Mangrove forests are important blue carbon ecosystems due to their ability to store carbon in aboveground biomass, belowground biomass, and soil. This study compared the carbon stock of natural and planted mangrove forests in Malita and Jose Abad Santos, Davao Occidental, Philippines. Carbon stocks were quantified using non-destructive quadrat and stratified random sampling across landward, mid, and seaward zones. Aboveground and belowground biomass was estimated using allometric equations, while soil organic carbon was determined through laboratory analysis and bulk density measurements. Total carbon stock in natural mangrove forests ranged from 372.28 to 8,167.92 Mg C ha⁻¹, whereas planted mangrove forests ranged from 245.92 to 2,506.52 Mg C ha⁻¹. The maximum carbon stock in natural forests was recorded in the landward zone of Transect 2 (8,167.92 Mg C ha⁻¹), while the highest value in planted forests occurred in the midzone of Transect 1 (2,506.52 Mg C ha⁻¹). Non-parametric analysis showed a significant effect of forest type on carbon stock (H= 16.81, p < .001), whereas ecological zone (H= 0.18, p= .914) and the forest type × zone interaction (H= 0.03, p= .987) were not significant. Correlation analyses indicated no significant relationships between total carbon stock and tree density or average basal area in either natural (r= .01–.48, p > .05) or planted forests (r= .32–.38, p > .05). These results demonstrate clear differences in carbon stock between natural and planted mangrove forest types.