Chapter Using multispectral UAV imagery and ground truthing to assess the success of vegetation reinforcement in a coastal area – the case of Inwadar National Park, Malta

Abstract

Ground-based methods of vegetation survey are slow and expensive, but recent technological developments have made UAVs (Unoccupied Aerial Vehicles or drones) accessible to consumer budgets, facilitating their use in vegetation monitoring. We propose a method for using UAVs to evaluate a vegetation reinforcement programme in a coastal area in Malta and compare its accuracy and cost-effectiveness with that of ground-based methods (including walkthrough-surveys and measurements of chlorophyll-a content). Multi-seasonal imaging of the site was captured using a DJI Phantom 4 drone equipped with sensors sensitive to visible, near infrared (NIR) and red edge (RE) light. These images were used to construct NDVIs of the site from which vegetation characteristics were deduced. Results suggest that UAVs provides a cost-effective way to map, quantify, and detect changes in vegetation cover which can enable assessment of physiological performance once a calibration procedure has been carried out. With an accuracy comparable to ground-based surveys, but quicker and cheaper, drone-based methods provide a viable and economically-attractive alternative to manual surveying methods.