IOWA – From tornados to ice storms to hurricanes, weather events take a toll on habitat, both natural and human. Before a storm has even cleared, questions about the extent of damage begin rolling in. Working with the Iowa Department of Natural Resources, researchers with the Northern Research Station‘s Forest Inventory and Analysis Program developed a technique for rapid assessment that is described in a new study published this month’s issue of Forests, a journal from the Multidisciplinary Digital Publishing Institute Journal.

The most accurate way to use FIA data to assess damage following a weather event is to remeasure a series of plots, according to lead author Thomas Goff, a forester with FIA based in Columbia, Missouri. “Given that plots are revisited over a 7-year time period, it could be years after the event before that information is available,” Goff said. “Emergency responders, insurance adjusters and officials working to determine appropriate levels of emergency funding from government agencies all need a more rapid assessment of damage.”

The Midwest Derecho of August 10-11, 2020, produced powerful straight-line winds and traveled 770 miles across Iowa and adjacent states. The storm damaged structures, crops and trees and knocked out electrical power for approximately 1 million people. It was the most expensive thunderstorm-related event since 1980. In response to a need for fast but still reliable estimates of damage to Iowa forest resources, researchers combined pre-disturbance forest inventory data with post-disturbance aerial survey to produce estimates of affected forest land area, and numbers of trees and total sound volume with new damage or mortality likely caused by the derecho.

The FIA assessment estimated that 2.67 million trees and 1.67 million m3 of sound bole volume were damaged or killed by the 2020 derecho. This study originated with the need for preliminary results so that Iowa officials could meet obligations for emergency funding following the August 2020 storm. After submitting estimates, the research team began working on techniques to make future assessments faster without compromising accuracy, and continued refinement of the method proposed is likely to continue.

In addition to outlining the methodology for rapid assessment, authors Mark Nelson, Greg Liknes, Scott Pugh and Randall Morin and Tivon Feeley of the Iowa Department of Natural Resources offer the caveats, cautions and lessons learned in rapid estimation of forest damage.