Evaluation of the effectiveness of UAV platforms in monitoring Pueraria lobata (Willd.) Ohwi subsp. lobata

Abstract

Pueraria lobata (Willd.) Ohwi subsp. lobata is listed as one of the top 100 invasive alien species in the world. In controlling P. lobata subsp. lobata, early detection and monitoring of invasions are the most important. UAV platforms should be useful for early detection and monitoring of P. lobata subsp. lobata invasions, but there are no cases of their application. Therefore, in this study, we aimed to evaluate the effectiveness of UAV platforms for monitoring P. lobata subsp. lobata in open spaces where P. lobata subsp. lobata invasions have been confirmed, and to obtain basic information for strategic management. The survey area was the forest of the Natural and Cultural Park (approx. 25 ha) in the Expo Commemorative Park (Suita City, Osaka Prefecture). Orthomosaic images were created using a UAV platform, and patch polygons of P. lobata subsp. lobata were created by visual interpretation. The distribution characteristics of P. lobata subsp. lobata were analyzed using Digital Canopy Height Model (DCHM) and park path data. In the Expo Commemorative Park, it was found that the patch area of P. lobata subsp. lobata increased 2.2 times from 2021 to 2024, and that the number of P. lobata subsp. lobata covering the tree canopy increased significantly. More than 83% of P. lobata subsp. lobata patches were distributed within 30 m of the park paths. It was found that P. lobata subsp. lobata was expanding to higher tree canopy heights. The UAV platform can be said to be effective for monitoring P. lobata subsp. lobata.