Abstract
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.
Highlights
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 objectives of this study were to (1) determine the extent of longleaf pine habitat in Florida impacted by Hurricane Michael using Geographic Information Systems (GIS) and the Longleaf Pine Ecosystem Geodatabase (LPEGDB)[39], (2) perform Before-After field surveys of tree density and estimate mortality by size class at four sites within the path of the storm using generalized linear models, and (3) compare damage types at these sites, which occur in different community types that differ in their soils, hydrology, and species composition
We show that Hurricane Michael resulted in varying rates of mortality on longleaf pines in the Florida Panhandle with the most severe impact highly localized to the center of the storm and resulting in catastrophic losses of mature canopy trees
Summary
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. 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[14,15,16,17]. While gap dynamics driven by typical tropical storm events, in addition to low intensity fires, play an important role in maintaining these open-canopied habitats, the potential for hurricanes of increasing strength to occur over the century[5,52,53] could lead to severe damage and potentially permanent losses of remnant stands of an already vulnerable system[12,35]. The loss of mature trees, creation of large canopy gaps, and severe damage to the understory from extreme events can have negative effects on numerous species that depend on mature trees, impede natural regeneration, alter the fire regime, increase the chance of invasive species establishment, and provide favorable conditions for insect outbreaks[4,5,56,57,58,59,60]
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