Integrating field measurement, remote sensing, and modeling approach to track forest cover and above ground biomass changes in the Northeast Asian temperate forests

This study aims to quantify changes in forest cover and carbon storage of Korean Peninsular during the last two decades by integrating field measurement, satellite remote sensing, and modeling approaches. The annual Landsat based forest cover change metrics and spaceborne lidar (Global Ecosystem Dynamics Investigation, GEDI) derived forest height were ingested into the forest growth model which reflects age, species, and climate-specific growth response to environmental changes. Our analysis based on 30-m Landsat data reveals that the forested area in Korean Peninsular has been diminished significantly by 478,334 ha during the period 2000-2019, and South and North Korea contribute 51.3 % (245,725 ha) and 48.6 % (232,610 ha) of the total change, respectively. This comparable pattern of forest loss in South and North Korea is likely due to both recent reduction of deforestation and degradation in North Korean forests and active forest management activity in South Korea. Our remote sensing based framework estimates respective aboveground biomass (AGB) of South and North Korea at 2000 to 211.5 Tg C and 277.1 Tg C. Independent validation and inter-comparison practices could assess our model performance and concluded that 70-77% of spatial variation in AGB can be explained in this study. Time series of AGB in the Korean Peninsula showed that South and North Korean forests increase their total AGB by 146.4 Tg C (AGB at 2020 = 357.9 Tg C) and 140.3 Tg C (AGB at 2020 = 417.4 Tg C) during the last two decades. This can be translated into a net AGB increase in South and North Korean forests from 34.8 and 29.4 Mg ha-1 C to 58.9 (+24.1) and 44.2 (+14.8) Mg C ha-1, respectively. It indicates that South Korean forests are more productive so have sequestered more carbon during the study period. Our approaches and results can provide useful information for quantifying national scale forest cover and carbon dynamics, and the results further can be utilized for supporting forest restoration planning in North Korea.