 United
States Department of Agriculture -
Forest Service |
 Southern Research Station200 W.T. Weaver Boulevard Asheville, NC 28804 |
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 Hurricane Katrina approaching the gulf coast, August 29,2005 Photo courtesy of NASA/JAXA |  US Forest Service employee Jim Gray measures trees in Mississippi after Hurricane Katrina Photo by Andy Edwards. |
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Measuring Impacts of Hurricane Katrina on Mississippi's Forest Resources
Knoxville,TN -- When Hurricane Katrina came ashore in August 2005, Mississippi forests took a beating from wind, rain, and tornado damage. The majority of the state experienced peak wind gusts exceeding 50 mph. Shortly afterwards, federal, state, and local government personnel began surveying the damage to aid in developing recovery and salvage logging plans. Forest Service Forest Inventory and Analysis (FIA) crews continued collecting data throughout Mississippi for two years. Southern Research Station FIA resource analysts Sonja Oswalt and Chris Oswalt wanted to examine how stand-level factors influence damage likelihood in forests in Mississippi. They also wanted to know how the initial estimates made using remote sensing compared to the data collected on the ground. In the article Relationships between Common Forest Metrics and Realized Impacts of Hurricane Katrina on Forest Resources in Mississippi, published in Forest Ecology and Management, Oswalt and Oswalt state that tree species and diameter at breast height (dbh) consistently affected the probability of trees suffering at least some wind-related damage in each zone of damage. Stand density was significant only in interaction with other main effect variables. Hurricane path and damage zones were developed by FIA research forester Dennis Jacobs. Zone numbers rose from one to five based on distance from landfall. The percentage of FIA survey plots experiencing damage decreased as distance from landfall increased, with the exception of zone five, the most western area. Damage in that zone was most likely also impacted by damage caused from spin-off tornado activity. Analysis revealed that damage figures calculated by models using remotely sensed data were comparable with on-the-ground inventory. Hardwood forests sustained more damage from Hurricane Katrina than softwoods. This likely relates to the dominance of hardwoods in forest composition rather than susceptibility to damage. Oswalt and Oswalt found that, in softwoods, stand spacing and tree height were more important than species type for determining potential breakage. The Oswalts believe that trying to reduce the vulnerability of forests to hurricanes by management may be subject to too many variables. Sonja Oswalt says, “We are not making recommendations for managing for stochastic wind events like a hurricane or tornado. While our data show that height and diameter play a role in the probability of damage, we were unable to successfully make predictions using those variables. ” For additional information, please contact Dr. Sonja Oswalt at 865-862-2058 or by email at soswalt@fs.fed.us You can read the full text of the article at http://www.srs.fs.usda.gov/pubs/29784
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