Bridhikitti A.Prasopsin S.Sawangproh W.Mahidol University2026-05-162026-05-162026-05-01Trees Forests and People Vol.25 (2026)https://repository.li.mahidol.ac.th/handle/123456789/116729Tropical karst forests are ecologically fragile ecosystems with shallow soils, high fire susceptibility, and limited recovery capacity, yet they function as important carbon reservoirs. This study quantified ecosystem carbon stocks, fire-induced potential carbon losses, and associated economic implications in mixed deciduous karst forests in Sai Yok, western Thailand. Field measurements in primary and secondary forests were used to assess tree biomass, understory biomass, soil carbon stocks, and vegetation diversity. Laboratory fire simulations at 300°C, 450°C, and 650°C represented low-, moderate-, and high-severity fires to quantify potential carbon losses from understory biomass and surface soils. Carbon stocks were further evaluated using Thailand's Voluntary Emission Reduction Program. Total ecosystem carbon stocks ranged from 246 to 693 t C ha⁻¹, with soil carbon dominating (64.6–79%), followed by tree biomass, while understory vegetation contributed minimally. Secondary forests showed higher tree density but lower biomass compared to primary forests, reflecting differences in successional stages. Fire simulations indicated that carbon losses increased sharply with fire severity, with biomass carbon loss ranging from 18 to 37% at low temperatures to over 97% under high-severity conditions, while soil carbon losses reached up to 95%. Carbon valuation indicated that effective carbon management in tropical karst forests requires including soil carbon in accounting frameworks and minimizing fire disturbances to maintain carbon stocks. Sustainable resource use and long-term monitoring are essential to balance carbon market benefits with ecosystem resilience.Environmental ScienceAgricultural and Biological SciencesEconomics, Econometrics and FinanceArticleSCOPUS10.1016/j.tfp.2026.1012952-s2.0-10503822281326667193