Canopy openings in the Trans-Mexican Neovolcanic Belt: Characteristics, distribution, and conservation relevance in a biosphere reserve

Canopy openings are key drivers of forest dynamics, influencing tree regeneration, species composition, and ecosystem resilience. However, their structural characteristics remain poorly quantified in Mexican forests, particularly in the Monarch Butterfly Biosphere Reserve (MBBR), where forest conservation is critical for maintaining the monarch butterfly’s wintering habitat. This study aimed to (i) quantify the size and density of canopy openings and the proportion of cleared area across management zones and forest types, (ii) assess their relationship with topographic factors, and (iii) determine their association with disturbances. Canopy openings were identified using the normalized difference vegetation index (NDVI) and Google Earth imagery. Results showed that core zones and Abies religiosa forests exhibited higher canopy opening density than buffer zones and pine-oak forests. The highest density of canopy openings occurred on gentle slopes (0-0.9°) and at high (>3000 m a.s.l.) and low (