European livestock systems are increasingly affected by climate change, particularly summer droughts and heatwaves. Integrating trees into pastures can mitigate these effects by providing shade and an additional forage resource. Tree leaves are generally less affected by summer weather extremes than herbaceous vegetation, have comparable nutritive value, and decline more slowly in quality, offering greater feeding flexibility (Mesbahi et al., 2025). However, knowledge on leaf biomass production in forage trees remains limited and highly variable among species and pruning practices (Larsen et al., 2025). Moreover, no standardized method exists to assess this biomass, as most approaches were developed for wood production. Destructive sampling is time-consuming, while allometric equations are often species-specific and difficult to generalize (Galland et al., 2025). Unmanned aerial vehicles (UAVs, or drones) are increasingly used to estimate tree height or crown area (Bossoukpe et al., 2021). Here, we evaluated whether UAV-derived metrics can estimate leaf biomass in four forage tree species.