The United States Department of Agriculture (USDA) conducts annual forest damage aerial surveys using fixed-wing aircraft along predetermined routes across Alaska’s forests, with up to 25% of the total forested area surveyed each year. Insect damage within one to two miles on either side of the flight path is recorded by drawing polygons onto 1:250,000 scale USGS topographic maps or a digital elevation model (DEM) (FS-R10-FHP 2012, 2013). Damage observed has been attributed with severity in three categories: high, moderate, and low. From 1999 to 2013, the period for which survey flight lines are available, approximately 105,545 km2, or 46% of the study area, was surveyed.
