<![CDATA[Abstract. Lestarina PM, Bengen DG, Prartono T, Rifa'i MA, Zamani NP, Selviani. 2026. Organic carbon in Rhizophora and Avicennia mangrove litter of South Kalimantan, Indonesia. Biodiversitas 27 (1): d270132. https://doi.org/10.13057/biodiv/d270132. Mangrove ecosystems serve as major blue carbon sinks due to their high productivity and slow decomposition under anaerobic conditions. This study examined organ and species-level variations in the organic carbon content of Rhizophora mucronata and Avicennia marina at two coastal sites in South Kalimantan, Indonesia-Kintap and Asam-Asam. Samples of stems, twigs, leaves, roots, and flowers were analyzed using the Walkley-Black method. The average organic carbon content of R. mucronata was 7.603%, while that of A. marina was 6.193%. The highest carbon concentration occurred in stems and twigs, followed by roots, leaves, and flowers. Mean carbon content was slightly higher in Kintap (7.091%) than in Asam-Asam (6.704%), though the difference was not statistically significant. Regression analysis indicated that plant organs significantly influenced organic carbon levels (p = 0.004), whereas location, station, and species did not. These findings emphasize that organ-specific characteristics-particularly lignin-rich woody tissues-are key determinants of carbon retention in mangroves. Incorporating such organ-level variability enhances the accuracy of blue carbon estimates and supports ecosystem-based conservation and climate mitigation strategies. Moreover, these findings highlight the ecological significance of organ-specific carbon storage in dominant mangrove species, reinforcing their role in sustaining ecosystem diversity and supporting blue carbon conservation strategies under global climate change agendas.]]>
