Reduction of mangrove carbon stock ecosystems due to illegal logging using a combination of unmanned aerial vehicle imagery and field surveys

BACKGROUND AND OBJECTIVES: Mangrove habitats play a vital role in the global carbon cycle, decreasing greenhouse gas emissions and mitigating the effects of climate change. Satellite images and aerial photography have been widely utilized to map the dynamics of mangrove ecosystems. These photos were used as inputs for international policy agreements, including Indonesia, in defining regulations about carbon dioxide emissions into the atmosphere caused by deforestation and land use changes. This study aimed to map forest to identify deforested areas and assess the effect of illegal logging on mangrove forest carbon stocks in Lubuk Kertang Village, North Sumtera, Indonesia using unmanned aerial vehicle imagery and field.METHODS: Photometric data analysis was obtained from high-resolution satellite imagery using a da-Jiang innovations Phantom 4 Professional at 150 meters’ altitude. Careful deployment of flight paths to obtain high accuracy in optimal image capture overlapped with 90 percent was conducted from August 5 to 8, 2023. Satellite imagery was captured in some areas considered important, such as rehabilitated mangrove forests and oil palm plantations. Both research sites produced orthophotos and digital surface models, and the integration of unmanned aerial vehicle with the photometry approach led to the development of the structure from motion method of data processing.FINDINGS: This study compared carbon stores in the mangrove forest of Lubuk Kertang Village in 2022 with carbon stock in 2023 or after the recurrence of illegal logging using an unmanned aerial vehicle photogrammetric field survey. The distribution of aboveground biomass in the mangrove covers an area of 253.4 hectares with total carbon in 2022 of 15.819 megagrams per hectare. Meanwhile, in 2023, the aboveground biomass was 70.94 megagrams per hectare with total carbon of 8.927 megagrams per hectare. This study shows that the mangrove forest in Lubuk Kertang Village has lost around 56 percent from the previous year. CONCLUSION: Illegal logging poses a significant threat to carbon sequestration/stock lost. This phenomenon highlights the need for improved monitoring and conservation strategies. The combination of remote sensing techniques and field surveys offers a powerful tool for blue carbon inventories, mangrove conservation planning, and monitoring climate, community, and biodiversity projects in coastal ecosystems.

Reduction of mangrove carbon stock ecosystems due to illegal logging using a combination of unmanned aerial vehicle imagery and field surveys Keywords:

Carbon storage , illegal logging , Mangrove forest , unmanned aerial vehicle (UAV)