The Impact of Land Use and Land Cover Changes on Carbon Storage and Sequestration in Coastal Ecosystems and Along the Elevation Using InVEST Model and Google Earth Engine Platform

Abstract

Coastal ecosystems play a pivotal role in climate change mitigation through carbon storage and sequestration, yet they are increasingly threatened by land use and land cover (LULC) change. This study investigates the spatiotemporal impacts of LULC change on carbon dynamics in Phang Nga Bay, southern Thailand, from 2000 to 2020, with a focus on elevation gradients. By integrating the Random Forest algorithm in Google Earth Engine (GEE) with the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) model, this study establishes a scalable, high-accuracy framework that overcomes the limitations of resource-intensive field assessments in complex coastal terrains. The results reveal extensive LULC changes, driven primarily by the expansion of oil palm plantations replacing evergreen and para rubber forests. These transitions led to a net carbon storage loss of approximately 821,000 Mg C, with the greatest losses occurring between 2000 and 2010. In contrast, mangrove forests, although covering only about one-fifth of the area, consistently contributed over 50 percent of carbon storage and showed localized gains in sequestration that offset some conversion losses. Carbon storage declined across all elevation zones, especially between 100 and 400 m, indicating agricultural expansion into upland forested areas. These findings highlight the need for elevation-sensitive land management and targeted conservation strategies that prioritize high-carbon ecosystems, particularly evergreen and mangrove forests, to ensure long-term carbon sequestration and resilience in tropical coastal landscapes.