Quantitative Assessment of Vegetation Carbon Stocks in Cacao Agroforestry Systems across the 3rd District of Bohol, Philippines

Cacao ( Theobroma cacao L.) agroforestry systems (CAFS) are multifunctional landscapes that simultaneously support livelihoods and deliver critical ecosystem services, including carbon sequestration. Globally, multi-strata cacao integrating diverse shade trees sequester significantly more carbon than monocultures; yet, detailed, pool-specific assessments in the Philippines remain limited, constraining their inclusion in national carbon accounting and climate mitigation strategies.. This study quantified vegetation carbon stocks across five municipalities in the Third District of Bohol, Philippines, capturing spatial variation in both above- and belowground pools. Field inventories of cacao and associated trees were conducted in seventy-nine (79) 25 × 25 m quadrats, with litter and understorey vegetation sampled destructively. Aboveground biomass was estimated using species-appropriate allometric equations, root biomass derived from established models, and total carbon calculated with a 45% carbon fraction. Descriptive statistics and ANOVA were used to examine carbon distribution and site-specific variability. Total carbon stocks ranged from 30.34 t C ha⁻¹ in Bilar to 174.96 t C ha⁻¹ in Pilar, with associated shade trees dominating the carbon pool (60–72%), cacao trees contributing 10–16%, and belowground biomass 15–16%. Minor pools, including litter and herbaceous vegetation, represented < 5% of total carbon. Spatial differences reflected variations in stand age, structural complexity, and management intensity rather than administrative boundaries. The results underscore that shade tree diversity and structural complexity are the primary drivers of carbon sequestration in CAFS. By providing precise, site-specific carbon estimates, this study informs climate-smart cacao management, strengthens evidence for agroforestry-based carbon mitigation, and supports sustainable land-use planning in tropical uplands