Aboveground biomass, carbon stock, and economic valuation of a tiny forest in a small Brazilian City

Abstract Urban forests have gained increasing attention as nature-based solutions, yet quantitative information on aboveground biomass and carbon storage in small urban forest remnants remains limited, particularly in small municipalities. This study aimed to quantify aboveground biomass, carbon stocks, and their illustrative economic valuation in an urban Tiny Forest located in southeastern Brazil. A complete tree inventory was conducted across a 2.76-ha area, including all living trees with a diameter at breast height (DBH) ≥ 5 cm. Aboveground biomass was estimated using an allometric equation developed for urban trees, carbon stocks were calculated using a conversion factor of 0.47, and an illustrative economic valuation was derived from a reference price in the voluntary carbon market. The inventory recorded 539 trees belonging to 68 species and 24 botanical families, with native species accounting for 79.0% of the individuals. Total aboveground biomass was estimated at 95.09 Mg (34.45 Mg ha⁻¹), corresponding to 44.69 Mg of carbon (16.19 Mg C ha⁻¹) and 163.88 Mg CO₂e. The illustrative economic valuation of the stored carbon was US$3,349.64. Native species accounted for 86.46% of the estimated carbon stock, with Moquilea tomentosa and Handroanthus impetiginosus among the main contributors. Carbon storage varied with species composition and tree structural characteristics, indicating that abundance alone does not determine species contributions to carbon stocks. These findings demonstrate that small urban forest remnants can represent measurable carbon reservoirs and provide local-scale information to support urban green infrastructure planning. However, the estimates represent carbon stocks at a single point in time and do not establish carbon sequestration rates or potential revenue from certified carbon credits.