Allometric Modelling of the Vegetative Carbon Content in Avicennia Marina in a Tropical Mangrove Ecosystem

Mangrove ecosystems play an important role in managing global climate change by sequestering carbon and mitigating the concentration of atmospheric carbon dioxide. This study constructed allometric equations to evaluate the carbon sequestration capacity of the stems, leaves, and above-ground roots of Avicennia marina, a prevalent species in a distinctive mangrove ecosystem in northern Sri Lanka. This study examined the allometric relationships between the carbon content of leaves (CL), stems (Cs), and above-ground roots (CR) and specific, measurable tree parameters of Avicennia marina, such as diameter at breast height (DBH), merchantable stem height (MSH), crown height (CH), leaf area (LA), total tree height (TH), above-ground root height (RH), and above-ground root diameter (RD). Stepwise regression modelling with backward elimination was used to develop these relationships in SPSS Version 26 statistical software. The allometric equations derived from the models for carbon content of stems (Ln Cs = -0.922 + 0.72 Ln DBH + 0.17 Ln LA), leaves (Ln CL = -0.647 + 0.335 Ln LA), and above-ground roots (Ln CR = -5.5 + 0.463 Ln RD) showed a reliability of 84.9%, 89.9%, and 62.5%, respectively. These models were identified as the best fit for predicting the respective carbon contents. They permit unrestricted reuse, distribution, and reproduction provided that the original article is properly cited. Based on the model bias value, modelling efficiency value, p-value, and residual plot, these models were identified as the best fit to predict the respective carbon contents of Avicennia marina. The allometric models developed in this study will be useful for monitoring the annual carbon sequestration potential of mangrove ecosystems in the Jaffna Lagoon in Sri Lanka. These models will also provide insight for assessing tradeable carbon credits in alignment with the REDD+ and Blue Carbon frameworks.