Soil organic carbon study in mangroves with diverse vegetation and seasonal variations

Abstract

Importance of the work: Mangroves are major global carbon sinks, where effective coastal
ecosystem management is crucial to understand seasonal soil organic carbon (SOC) dynamics.
Objectives: To analyze the spatial distribution and seasonal variation in SOC in the mangrove
forest of Segara Anakan Lagoon, Indonesia.
Materials and Methods: An observational method with purposive sampling was
used across two primary stations, each containing three sites with five replicate plots
(30 plots total). Sampling was conducted during four seasonal periods May 2023–February
2024. The main parameter measured was SOC concentration, with supporting variables
including temperature, salinity and pH.
Results: The highest mean ± SD SOC concentration (3.09 ± 0.61%) was at Station 1.1,
dominated by Sonneratia caseolaris (L.) Engl., while the lowest (1.61 ± 0.34%) occurred
at Station 2.1, characterized by Acanthus ilicifolius L. and Derris trifoliata Lour., indicating
ecosystem degradation. Seasonally, the SOC peaked in February (3.98 ± 0.12%) and was
lowest in August (1.20 ± 0.39%). Dunn’s post-hoc test showed significant differences in SOC
between the dry and rainy seasons and across transitional periods. Principal components
analysis revealed strong associations between SOC, rainfall and the number of rainy days.
During the rainy season, increased litterfall and soil moisture supported anaerobic conditions,
slowing decomposition and enhancing SOC accumulation.
Main finding: The distribution of SOC concentrations in the Segara Anakan Lagoon was
influenced by litter productivity and rainfall patterns.