Vegetation monitoring in areas affected by plant pathogens is essential for assessing the vulnerability of plant communities and supporting the management of infected territories. Although field surveys remain the cornerstone of vegetation monitoring, RGB UAV technology is increasingly proving its value at local and regional scales for mapping plant communities and detecting diagnostic species of Annex I habitats. This study presents the results of a vegetation monitoring program carried out in 2021 and 2025 in a natural area of Monte Argentario (southern Tuscany, Italy), where Xylella fastidiosa subsp. multiplex ST87 has been spreading since 2018. Field surveys were integrated with UAV-based photogrammetric mapping and photointerpretation of ultra-high-resolution orthomosaics over a 2.5 ha polygon encompassing a mosaic of three Natura 2000 habitats (H9340, H5330, and H6220*). Multivariate analyses identified three floristically distinct assemblages corresponding to the main habitat types, and species-area analysis confirmed the representativeness of the sampling design. Comparing the two survey campaigns, the plant community showed remarkable compositional stability: species richness remained unchanged, and the minor increase in Shannon diversity reflected subtle shifts in relative dominance rather than any directional floristic change. Among the Xylella target species, Cytisus laniger showed a significant and counter-intuitive increase in cover, possibly reflecting a pre-symptomatic phase of infection or the intrinsic canopy expansion dynamics of this fast-growing resprouting shrub. The study establishes an important pre-symptomatic baseline for long-term monitoring of these habitats.
UAV-based RGB imagery for assessing vegetation status in a Mediterranean area affected by Xylella fastidiosa 1
Diego Orazi;Tiziana Lombardi
2026-01-01
Abstract
Vegetation monitoring in areas affected by plant pathogens is essential for assessing the vulnerability of plant communities and supporting the management of infected territories. Although field surveys remain the cornerstone of vegetation monitoring, RGB UAV technology is increasingly proving its value at local and regional scales for mapping plant communities and detecting diagnostic species of Annex I habitats. This study presents the results of a vegetation monitoring program carried out in 2021 and 2025 in a natural area of Monte Argentario (southern Tuscany, Italy), where Xylella fastidiosa subsp. multiplex ST87 has been spreading since 2018. Field surveys were integrated with UAV-based photogrammetric mapping and photointerpretation of ultra-high-resolution orthomosaics over a 2.5 ha polygon encompassing a mosaic of three Natura 2000 habitats (H9340, H5330, and H6220*). Multivariate analyses identified three floristically distinct assemblages corresponding to the main habitat types, and species-area analysis confirmed the representativeness of the sampling design. Comparing the two survey campaigns, the plant community showed remarkable compositional stability: species richness remained unchanged, and the minor increase in Shannon diversity reflected subtle shifts in relative dominance rather than any directional floristic change. Among the Xylella target species, Cytisus laniger showed a significant and counter-intuitive increase in cover, possibly reflecting a pre-symptomatic phase of infection or the intrinsic canopy expansion dynamics of this fast-growing resprouting shrub. The study establishes an important pre-symptomatic baseline for long-term monitoring of these habitats.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
