Using UAV (drone) technology to measure the dynamics of Abies religiosa (Kunth) Schltdl. & Cham. decline in the Monarch Butterfly Biosphere Reserve, Mexico, and its relationship to climate change

A significant decline in the health of Abies religiosa trees within Mexico's Monarch Butterfly Biosphere Reserve (MBBR) was linked to extreme drought conditions exacerbated by climate change. Using UAV technology, researchers detected a sharp drop in tree vigor—measured via NDVI and a new Monthly Dryness Index (MDI)—during a June 2023 heat wave (+2.7°C anomaly), with healthy trees plummeting from 37% to 18%. Regression models confirmed MDI's strong predictive power (R² ≥ 0.94) for tree vitality shifts, underscoring the species' vulnerability during dry seasons. This study highlights how drone-based remote sensing can track climate impacts on ecosystems in real time.

Gallardo-Salazar, J. L., Lindig-Cisneros, R., Lopez-Toledo, L., Endara-Agramont, A. R., Blanco-García, A., García-Serrano, E., Guadarrama-León, R., & Sáenz-Romero, C. (2026). Using UAV (drone) technology to measure the dynamics of Abies religiosa (Kunth) Schltdl. & Cham. decline in the Monarch Butterfly Biosphere Reserve, Mexico, and its relationship to climate change. The Forestry Chronicle, 1–18. https://doi.org/10.5558/tfc2026-001