Assessing Vegetation Disturbance Resulting from Extreme Windthrow Events

Toppled trees

Tornado damage and toppled trees assessment.

By Sergio Bernardes and Christopher Strother

In April 2011, a tornado outbreak hit the Southeastern U.S., with dozens of tornadoes touching ground and causing major damage to property and natural ecosystems. In one event, on April 27, an EF4 tornado left a long strip of damaged vegetation on the west side of the Great Smoky Mountains National Park (GRSM). Strong winds exceeding 200 miles per hour broke branches and toppled thousands of old-growth forest trees.

Disturbances of such magnitude may permanently affect the structure and composition of vegetation communities, changing local ecosystems and impacting their services. Little is known of the extent of ecological consequences resulting from extreme windthrow events, partly due to our inability to adequately characterize and monitor wind-driven vegetation disturbance over large areas.

This research uses remote sensing techniques, including digital image processing, to analyze tornado damage in the GRSM resulting from the April 2011 tornado outbreak. Analyses involve the characterization and mapping of the area affected by the GRSM tornado, including the classification of areas by damage severity and vegetation associations affected.

Tornado path

April 2011 tornado path at the Great Smoky Mountains National Park and spatial variation in wind damage severity.

See below for an animation of the April 27, 2011 tornado path and damage assessment next to Pine Mountain, Great Smoky Mountains National Park.

Results from this investigation will be presented at the Remote Sensing of Extreme Climate and Weather Events Special Session at the ASPRS 2013 Annual Conference, in Baltimore, Maryland.