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Post Katrina Study Assesses New Gulf Coast Region's Ecological Impacts and Fire Risks

BILOXI, MS (May 30, 2007)—Gulf Coast counties along the path of Hurricane Katrina lost the greatest amount of tree canopy, and suffered the greatest impacts in terms of increased stormwater runoff and poorer air and water quality.

American Forests just completed a 30,000 square mileregional assessment of the impacts Hurricane Katrina had in Louisiana,Mississippi and Alabamaby comparing landcover from 2001 and 2006. The findings show that the greatestconcentrated loss in tree cover was measured in St. Tammany and WashingtonCounties in LA and in Hancock, Pearl River,Lamar, Forrest, Stone and Harrison Countiesin MS. These counties were directly in the path of the Hurricane. The loss intree canopy also means a reduction in the environmental benefits that urbanforests and other vegetation provides to these communities.

The data compiled in this assessment not only provides thebasis for the findings in this report, but is also prepared for on-going use bythe cities, counties and states within the study area.

Moderate resolution Landsat satellite imagery and GeographicInformation Systems (GIS) software was used to 1) assess the change inlandcover pre and post hurricane and the impacts these changes had on air andwater and 2) update post-hurricane landcover data used by state forestryagencies for fire management. The study covers 23 counties in Louisiana,20 counties in Mississippi, and 5 counties in Alabama.

In August of 2005 Hurricane Katrina slammed into the Gulf Coast and changed the physicalmakeup of tens of thousands of square miles of land. Along with the human made infrastructure,natural systems such as forests and streams were damaged. Accounting for the impacts to the naturalsystem in terms of wildfire susceptibility and ecosystem services losses is anecessary part of the recovery process, as is supporting local decision makerswith the data and management tools they need to make good decisions aboutrebuilding the area. The data willprovide local planning agencies with the base maps and technical modeling toolsneeded to rebuild their communities to take advantage of the ecosystem servicesthat natural systems provide in terms of cleaner air and water and reducedstormwater runoff and erosion.

The data will also be used to update wildfire risk in thesepredominately rural regions of the country. The updated digital data will beincorporated into a wild land fire risk model (Southern Fire Risk AssessmentSoftware) that will quantify the effects of the storm damage on wildfire riskin the region, pinpointing areas where risk has increased. This will enable theUS Forest Service, Southern Group of State Foresters, and state agency firechiefs to prioritize areas for managing vegetation for fuel reduction.

The most evident changes occurred in the city of Gulfport,MS. The area lost 13% of its tree canopy and gained 12% shrub cover and 4% ofits open space in the five year time span. At the same time the area onlygained 4% urban (impervious surfaces) area. These changes indicate thathurricane damage rather than development caused the majority of the landcover changes.The city’s 13% percent loss tree canopy increased the need to manage an additional305,000 cubic feet of stormwater management, valued at $610,500. The loss ofcanopy also resulted in a 28,000 pounds loss of air pollution removal, valuedat $68,000 annually; and a 10,700 ton loss of carbon storage and a 83 poundloss of carbon sequestration annually.

Inaddition to the regional study, high resolution satellite imagery was analyzedof St. Louis Bayand a portion of Biloxi. "Thisstudy provides local leaders and state agencies with the data and softwaretools they need to rebuild their communities with an understanding of thenatural conditions on the land," explains Gary Moll,senior vice president of the Urban Ecosystem Center at American Forests. "Thebase maps, wildfire fuel modeling and urban ecosystem analyses will provide thetechnical capacity needed by local planning agencies for modeling scenarios forland planning." American Forests will also provide technical assistance andtraining to agency personnel on the air, and water impacts and benefitsproduced by natural systems and train them to use software tools for makingdecisions.

This project was sponsored by the USDA Forest Service. TheAnalysis was conducted by American Forestsand Sanborn.

American Forests emphasizes the important role that greeninfrastructure plays in air and water quality and stormwater runoff in urbanareas. Trees help reduce stormwater runoff by intercepting rainwater, allowingit to evaporate or soak slowly into the ground. Trees absorb air pollutants andtheir roots filter pollutants from the water.

Gary Moll
American Forests
P.O. Box 2000
Washington DC 20013
Remote Sensing, Storms (hurricane), Fire
Alabama, Louisiana, Mississippi
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