Unmanned aerial vehicles for assessing biomass and carbon stocks in mangrove forests: A systematic review

Unmanned Aerial Vehicles (UAVs) have become transformative tools for monitoring mangrove ecosystems, offering high-resolution data for biomass, carbon stock, and ecosystem health assessments. This review screened 279 publications and analyzed 19 that explicitly applied UAVs to mangrove carbon studies. Most studies employed RGB cameras and LiDAR sensors in China, Indonesia, Malaysia, Australia, and Colombia. Biomass analysis centered on Above-Ground Biomass (AGB), ranging from 9.26 Mg/ha to 128.27 Mg/ha, while carbon stock assessments included Above-Ground Carbon (AGC) and Below-Ground Carbon (BGC), ranging from 42.86 Mg C/ha to 400.1 Mg C/ha for AGC and 20.81 Mg C/ha to 21.1 Mg C/ha for BGC. Combinations of RGB and LiDAR sensors produced more accurate AGC estimates, yet consistent approaches for BGC remain limited. These findings underscore mangroves’ role in carbon sequestration and climate mitigation. UAV proved effective in capturing structural and temporal data, particularly in remote environments. Integration with machine learning and satellite imagery further enhanced accuracy and scalability. However, major gaps persist: BGC estimation is uncertain, geographic coverage uneven, and standardized methodologies lacking. The review advances beyond earlier syntheses by highlighting methodological limitations, geographic imbalances, and validation challenges, while identifying opportunities in UAV-satellite integration and machine learning. With advancements in UAV technology, such as thermal imaging and open-source platforms, the scalability and accessibility of these tools are expected to improve, enabling broader adoption for environmental monitoring. UAVs are poised to become indispensable for addressing the dual challenges of mangrove ecosystem conservation and climate change mitigation.