Impacts of mangrove land use change on carbon stocks in coastal ecosystems

BACKGROUND AND OBJECTIVES: Mangrove ecosystems are critical blue carbon reservoirs, yet carbon dynamics in intensively used coastal landscapes remain poorly understood. Along the northern coast of Java, aquaculture expansion, rehabilitation, and community-based management coexist within the same coastal mosaic. This study aims to examine how land-use trajectory influences ecosystem carbon stocks and carbon partitioning across recovered, semi-natural, and degraded mangrove systems.METHODS: Total ecosystem carbon stocks, including aboveground biomass, belowground biomass, and soil organic carbon to ۱۵۰ centimetres depth, were quantified across representative sites. Differences among land-use treatments were tested using non-parametric statistics (Kruskal–Wallis and Dunn’s tests), and Spearman correlation analysis was applied to assess relationships between years since land-use change and carbon stocks. Community interviews were incorporated to contextualize management practices and land-use history.  FINDINGS:  Total ecosystem carbon stocks ranged from ۱۲۱.۶۳ ± ۳۳.۹۱ to ۲۱۷.۸۶ ± ۱۶۱.۲۷ megagrams of carbon per hectare, with the highest values observed in semi-natural mangrove systems and the lowest in long-term degraded sites. Statistical analyses showed no significant differences in total carbon stocks among recovered, semi-natural, and degraded mangroves. Instead, land-use trajectories strongly influenced carbon partitioning. Soil carbon dominated ecosystem carbon storage, contributing ۷۱.۸–۹۳.۵ percent of total carbon, while biomass carbon accounted for only ۶.۵–۲۹ percent. Vertical soil profiles revealed that deep soil layers (۵۰–۱۵۰ centimetres) contained the largest carbon pools, indicating that long-term sedimentary processes govern carbon storage. Correlation analyses showed weak relationships between total carbon stocks and years since land-use change, highlighting strong legacy effects in subsurface carbon pools. CONCLUSION:  These results demonstrate that mangrove carbon storage in working coastal landscapes is controlled by sediment properties, hydrological connectivity, and long-term disturbance history, rather than land-use classification alone. The persistence of deep soil carbon pools explains why ecosystem carbon stocks remain relatively stable even in aquaculture-dominated landscapes where vegetation structure varies substantially. Effective blue carbon management should therefore prioritize protecting existing soil carbon and maintaining hydrological connectivity, particularly in semi-natural systems with long-term sediment stability. This study provides empirical evidence supporting process-based mangrove management and more nuanced coastal land-use policies in rapidly developing tropical coastlines.

کلیدواژه ها:

Aquaculture ، Carbon stock ، Coastal ، Land-use management ، mangrove ، Indonesia.