Time-series analysis of carbon density over Malaysia’s forests using open-access Landsat imagery on Google Earth Engine platform

Abstract The production of high-resolution carbon density map at national level requires substantial amount of data and time-consuming. This study presents estimates of aboveground carbon density (ACD) changes over the forests that have occurred in the previous three decades in the State of Johor, as a case study. The entire process was streamlined by Google Earth Engine (GEE), which makes it effective and scalable. The ACD estimation was produced based on the Aboveground Carbon Density Indicator (ACDI) generated from Landsat imagery datasets. Based on the estimates, a 30-metre resolution, wall-to-wall map of AGC across the entire forested region of Johor has been created. Forest cover carbon density changes have been assessed for the period between 1990 and 2023, with a chrono sequence of years 1990, 2010, 2016 and 2023. Results indicated that the ACD has reduced 28.49 million Mg C, which was from 113.4 to 84.91 million Mg C in years 1990 and 2023, respectively. The high-resolution maps products offer valuable information for various stakeholders, with important implications for carbon sequestration efforts, conservation goals, and sustainable forest management. The methodology demonstrated the effectiveness of using open-access datasets and open-source GEE technologies to generate AGC information at the sub-national and national levels. This research will eventually increase our understanding of carbon dynamics in Malaysian forests and stimulate the implementation of realistic forest management and conservation practices in order to use forest resources responsibly and mitigate the consequences of climate change.