VOLUME 18 (Supplement)

Mangrove extent mapping using different mangrove vegetation indices and sentinel-2 for ecosystem accounting in Occidental Mindoro, Philippines

The Philippines is home to about half of the world's 65 mangrove species, representing 50% of mangroves globally. As an archipelagic country, mangrove forests offer a variety of ecosystem goods and services, from coastal protection to carbon sequestration, which play a vital role in climate change mitigation. Understanding mangroves' changing extent and condition is critical and valued, as these impact climate, biodiversity, and ecosystem service provision. However, little has been done to account for these attributes. Thus, the study aimed to construct physical ecosystem accounts for mangroves in Occidental Mindoro, Philippines, encompassing spatial distribution and extent, and develop a physical accounting table. Using cloud-based remote sensing on the Google Earth Engine (GEE) platform, this research contributes to broader ecosystem accounting efforts for the West Philippine Sea, providing evidence-based insights for effective policymaking and decision-making. Mangrove extent modeling was conducted using a three-tiered approach, guided by the spatial framework of the System of Environmental-Economic Accounting (SEEA) Ecosystem Accounting, to improve accuracy.

Vegetation indices such as Mangrove Vegetation, Normalized Difference Vegetation, Normalized Difference Mangrove, Modified Normalized Difference Water, and the Green Chlorophyll Vegetation were employed. Statistical parameters for feature objects were selected and applied in the random forest classifier. In 2021-2023, during the dry season with lesser clouds, composite images were produced by combining spatially overlapping ones into a single picture based on an aggregation function. These indices delineated the area of mangroves using remotely sensed imagery efficiently and precisely. Combining these spectral indices resulted in an overall mangrove extent of about 2,096.74 ha, with an overall classification accuracy of 87.33 percent and a Kappa coefficient of 0.80. Similarly, Sentinel-2A images and the GEE platform accurately assessed changes in the extent of mangrove forests within the coastal ecosystems of the West Philippine Sea.