The use of UAV-based systems in monitoring forest health: Potentials and challenges

Natural ecosystems, especially forests, are undergoing severe degradation due to climate change and human-induced actions like forest clearance, environmental pollution, and modifications to land utilization. This systematic review synthesizes recent research on using unmanned aerial vehicles (UAVs) for forest health monitoring (FHM), specifically focusing on detecting tree stress and assessing overall forest health through vegetation indices. The UAVs have emerged as a leading tool in FHM because they provide high-resolution imagery and flexible operational capabilities. Adhering to the Preferred Reporting Items for Systematic Reviews and Meta‑Analyses (PRISMA) guidelines, this review ensured a thorough and transparent synthesis of information, enhancing the reliability of evidence for informed decision-making. This systematic review analyzed 40 studies conducted across 23 countries. The results highlighted the versatility of UAVs in addressing abiotic stressors such as drought and fire, which are becoming increasingly relevant due to climate change. The findings underscore UAVs' significant role in detecting phytoparasitic infestations that impact tree vitality, thereby improving forest management practices. Various tree species were examined concerning specific threats posed by pests and diseases, such as Norway spruce (Picea abies) affected by honey fungus (Armillaria) and Scots pine (Pinus sylvestris) impacted by the pine processionary moth (Thaumetopoea pityocampa). This complexity reflects the intricate nature of forest ecosystems and the unique challenges biological stressors present. Overall, integrating UAV technology into forest health monitoring represents a substantial advancement in enhancing management strategies amid environmental challenges, especially for African vegetation and forest health, through improved monitoring capabilities and sustainable management practices.