A meta-analysis of aboveground and belowground biomass and carbon stocks across major forest types in Cambodia

Cambodia’s forests—evergreen, semi-evergreen, deciduous (including dry dipterocarp), flooded forests, and mangroves—store substantial carbon in living biomass, but estimates of aboveground biomass (AGB), belowground biomass (BGB), and biomass carbon vary widely among studies because of differences in allometric equations, diameter thresholds, plot designs, wood density inputs, height models, carbon fractions, and root-to-shoot assumptions. This meta-analysis-style review synthesizes Cambodia-relevant peer-reviewed literature and national MRV/REDD+ technical evidence to (i) describes expected AGB/BGB patterns across major forest types, (ii) identify dominant sources of heterogeneity and uncertainty, and (iii) provide a meta-analysis workflow (random-effects pooling + moderator analysis) that can be applied once study-level estimates are extracted. Using Cambodia’s Second Forest Reference Level (FRL) as a harmonized benchmark, semi-evergreen and evergreen forests generally show the highest AGB and biomass carbon, deciduous and flooded forests are lower, and mangroves exhibit comparatively high BGB (via higher root-to-shoot ratios and mangrove-specific allometry). We recommend Cambodia-focused meta-analyses adopt transparent harmonization rules (units, carbon fraction, CO₂ conversion), stratify by forest type and disturbance, and test methodological moderators (allometry family; inclusion of height and wood density; DBH threshold; plot size; and BGB method).