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RESEARCH NOTES
Damage from Hurricane Michael to longleaf pine woodlands in southwest Georgia
By Dr. Jeffery B. Cannon and Brandon T. Rutledge
HOW DO HURRICANES SHAPE
longleaf pine ecosystems?
Photos courtesy of The Jones Center at Ichauway
Disturbance in longleaf pine forests Readers of this publication are familiar with the importance of low-intensity fire for healthy and biodiverse longleaf pine (Pinus palustris) forests. A century of research reveals fire’s principal place in the cycle of plant death and birth that supports the high diversity and open structure of pine woodlands1. As a coastal species, longleaf pine endures less frequent, but potentially catastrophic winds from hurricanes. Like fire, wind can be an important force that shapes the development and change within a longleaf forest. High-intensity winds can cause elevated levels of mortality, release resource-starved saplings from their taller competitors, shift dominance among understory plants, and even alter the frequency or intensity of future fires2. It is difficult to overstate the intensity of hurricane impacts on coastal forests. Winds from Hurricane Michael (2018) affected a substantial portion of longleaf pine habitat, causing mortality rates that rose from 15% on the outer edges of the storm to 88% near its center3. Even more dramatically, Hurricane Katrina (2005) toppled enough trees to set back an entire year’s worth of the nation’s forest growth4.
Longleaf as a wind-resistant species Climate forecasts of the southeastern U.S forewarn of increased drought, heightened risk of wildfire, and intense hurricanes that pose elevated risk to forests5. Recent research proposes longleaf pine as a candidate for more drought-resistant forestry6. With its thick bark, resinous needles, and brevity of vulnerable growth stages, longleaf pine has long been known as a fire-resistant species7. But could longleaf pine also fare better in a world with more extreme hurricanes? Pines are important to the ecology and economy of the Southeast, and longleaf pine occurs in hurricane-prone areas throughout its range. Nevertheless, little research rigorously tests wind resistance of the species. Several post-hurricane studies have documented fewer numbers of longleaf pine killed or damaged by severe winds compared to other species. Drawing conclusions from these studies is a challenge as they do not account for other important wind risk factors such as soil type and tree size. Apples-to-oranges comparisons of mortality can complicate conclusions about wind risk. To illustrate, slash pine is thought to be more vulnerable to wind compared to longleaf pine, but the species naturally occurs on wetter soils which can accentuate
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