IMPROVING ESTIMATES OF MANGROVE SOIL ORGANIC CARBON STOCKS BY CONSIDERING SOIL PHYSICOCHEMICAL PROPERTIES

The organic carbon sequestered by the world’s mangrove forests plays a key role in the global carbon cycle and may be central to climate change mitigation. This is because mangroves typically exhibit high rates of net primary production and greater carbon sequestration capacity compared to terrestrial ecosystems. This study investigated the influence of selected soil physicochemical properties on the soil organic carbon (SOC) content of Rekawa mangrove forest, Sri Lanka. The effect of soil pH, salinity, conductivity, moisture content (%), bulk density, porosity, phosphate, and nitrate content on SOC was examined along an intertidal gradient. Results showed, SOC was positively correlated with salinity (r² = 0.74), conductivity (r² = 0.76), moisture content (r² = 0.76), porosity (r² = 0.92), and phosphate content (r² = 0.74) while SOC was negatively correlated with bulk density (r² = -0.92) across the entire intertidal zone. Generalised Linear Model (GLM) resolved SOC to be best predicted as a function of soil porosity and soil moisture content [Akaike Information Criterion (AIC): 142.04], with other soil properties modulating the results within some zones. Overall, the present study shows that specific consideration of soil physicochemical properties could allow improved estimates of total carbon stocks which are becoming increasingly important for carbon accounting and national inventories