Mangrove Carbon Stock Calculator

Mangroves are prized as "blue carbon" ecosystems because they store carbon in three separate pools, and this calculator estimates all three rather than just counting trees. Above-ground biomass per tree comes from the Komiyama et al. (2005) allometric equation ("Common allometric equations for estimating the tree weight of mangroves," Journal of Tropical Ecology), which predicts dry biomass from trunk diameter at breast height (DBH) raised to the 2.46 power — a relationship derived from destructive tree-harvest studies across mangrove species — scaled by an assumed average wood density of 0.7 g/cm³. That per-tree figure is multiplied by tree density to get above-ground biomass per hectare, then below-ground (root) biomass is estimated at 39% of above-ground biomass, a standard root:shoot ratio from the same literature rather than a separately measured input.

Both biomass pools are converted to carbon using the common assumption that dry plant matter is about 47% carbon by mass. Soil organic carbon is calculated independently from the trees entirely: it's a function of how deep you sample, the soil's bulk density, and its measured organic carbon percentage, scaled up to a full hectare — and in mangrove soils this pool is often the largest of the three, sometimes dwarfing the biomass carbon above it. The final CO2-equivalent and carbon-credit-value outputs are straightforward conversions (carbon × 3.67 for CO2, times a $15/tonne mid-range voluntary-market price) and should be treated as rough planning estimates, not a number a real carbon-credit buyer would accept without field verification.