Global biodiversity hotspots (GBHs) are increasingly vulnerable to human stressors such as anthropogenic climate change, which will alter the ecology of these habitats, even where protected. the longleaf pine (Pinus palustris) ecosystem (Lpe) of the north American coastal plain is a GBH where disturbances are integral for ecosystem maintenance. However, stronger storms due to climate change may be outside their historical norm. in this study, we estimate the extent of florida Lpe that was directly affected by Hurricane Michael in 2018, an unprecedented Category 5 storm. We then leveraged a unique data set in a Before-After study of four sites within this region. We used variable-area transects and generalized linear mixed-effects models to estimate tree densities and logistic regression to estimate mortality by size class. We found at least 28% of the global total remaining extent of LPE was affected in Florida alone. Mortality was highest in medium sized trees (30-45 cm dbh) and ranged from 4.6-15.4% at sites further from the storm center, but increased to 87.8% near the storm center. As the frequency and intensity of extreme events increases, management plans to mitigate climate change need to account for large-scale stochastic mortality events to preserve critical habitats. Ecological disturbances play an integral role in maintaining ecosystem structure and functioning 1-3. Many ecological disturbances are expected to change with anthropogenic climate change 4 , altering the frequency, intensity, duration, and timing of events 5. Shifting disturbance regimes due to climate change pose a threat to the conservation of biodiversity as species experience conditions outside their historical norms 6-8. In savanna systems, which are characterized by a grassy or herbaceous understory and low tree densities, changing disturbance regimes can trigger demographic transitions altering the density of trees 9-11 , upon which biodiversity depends. Longleaf pine (Pinus palustris Mill.) habitats located within the North American Coastal Plain (NACP) are a global biodiversity hotspot 12,13. These savanna-type systems provide critical habitat for numerous endangered plant and animal species, which are dependent on the presence of sparse but critically important mature longleaf pine trees 14-17. The canopy of longleaf pine habitats is generally monotypic, with a range of tree densities (from <100 to 300+ tree/ha), a largely open canopy, and an herbaceous, grass dominated understory 18-20. Frequent seasonal fire is an integral part of this ecosystem and is the most important process for maintaining ecosystem structure and function 12,21-24. The highest quality stands are dominated by mature trees with a sufficiently frequent fire interval (1-5 year return) to promote regeneration and maintain a highly biodiverse understory-containing as many as >40 species per m 2,17,25-28. Canopy gaps are critical in promoting this biodiverse understory 29 and allow for recruitment and regeneration of longleaf pine 30,31. Gaps allow for greater li...