Carbon loss hotspots in Loma Mountains National Park

By Mees Huisman

Abstract
Tropical forests have a high carbon sequestration potential, making them crucial for climate change mitigation. Most tropical forests are located in developing countries, where conversion of forests to agricultural land is common. This pressure calls for effective forest monitoring, allowing carbon loss hotspots to be identified and targeted policy to be put in place. Remote sensing products may facilitate the implementation of a forest monitoring program, through the use of global deforestation and aboveground biomass products. These products are widely available but may fail to capture local characteristics specific to an area of interest. The goal of this study is therefore to gain insight into the patterns and amount of carbon loss from deforestation using local aboveground biomass data in the Loma Mountains National Park in Sierra Leone. In this study, aboveground biomass data of the forests in the park was collected and used to adjust the global Climate Change Initiative (CCI) 2020 Biomass product. In addition, 2 annual deforestation products and 2 near real-time products were compared to assess where they agree and where they differ in detecting deforestation. Subsequently, deforestation patterns were combined with field aboveground biomass data to identify carbon loss hotspots in the area. This study found that the CCI Biomass product underestimates aboveground biomass in and surrounding the park. Following the comparison of deforestation products, Tropical Moist Forests was found to detect more forest loss, and on smaller scale compared to Global Forest Change. For the near real-time products, Radar for Detecting Deforestation Alerts was found to provide the most extensive overview of monthly patterns compared to Global Land Analysis and Discovery Alerts, although validation of the detected patches is still required. Using the annual products, two main carbon loss hotspots were identified, one of which is entangled with a discrepancy in the park boundaries described by literature and the boundaries perceived by the inhabitants of the region. The ambiguity surrounding the park boundary may increase carbon loss inside the park in the future. In a broader context, the results of this study provide evidence that global biomass products may benefit from the incorporation of local biomass data. In addition, the choice of which deforestation product to use in forest monitoring requires weighing of the amount of forest disturbances that need to be detected and the capacity to validate them.