A significant number of mature Austrian Pines planted along a roadside greenbelt behind my house are dying. The area is located between a subdivision and a 40 mph roadway. In 2012, my subdivision cleared the variety of growth under the trees and also bottom cut the branches of most all the fir trees to a bottom height of about six feet. Last year, three (3) dead Austrian pines were removed from behind my property (12"+ diameter) and another one fell over a few houses down). Many more have brown needles and appear dead. My question is whether there is a disease currently affecting Austrian Pines, or if the clearing/tree trimming done in 2012 may have contributed to this situation.