Digital Mapping Of Invasive Acacia Mangium Willd. Trees Along Telisai-Lumut Highway Along The Andulau Forest Reserve

Abstract

Invasive alien Acacia trees have become a serious environmental problem in Brunei Darussalam, spreading into the vulnerable heath and mixed dipterocarp forest ecosystem where it has started replacing the native flora and contributing to forest fire.In this work, we study the spread of Acacia trees by analyzing images taken by drones along a newly developed highway within the vicinity of Andulau Forest Reserve in Brunei Darussalam. Based on the analysis, we aim to understand the Acacia spread and its habitat preference, which will be a critical factor in planning the future roadmap to maintain a sustainable and healthy forest ecosystem, and safety from potential forest fires. The Unmanned Aerial Vehicles (UAVs) were utilized to capture high-resolution images along the Telisai-Lumut highway and were subsequently analyzed images using ArcGIS software, to map and study the Acacia's distribution and habitat preferences, which will aid in understanding of Acacia's rapid dispersion. Our preliminary results show highest Acacia density and numbers closer to the highway. The barren loose sandy soil combined with the open terrain limits local forest tree growth but seems to provide good habitat for Acacia trees. Our results suggest that the highway provides an important dispersal opportunity for Acacia trees, bringing them in direct proximity of an undisturbed forest reserve. This may increase the risk of spread of this species into the forest, and importantly, given the fire proneness of Acacia, may lead to wildfires that threaten the neighbouring forest reserve. Keeping vegetation short and removing Acacia's close to the highway may mitigate these risks. Efforts such as spreading awareness on Acacia's invasiveness, identification and removal of Acacia trees, habitat restoration projects and meticulous evaluation for any introduced species should be done.