As woods and forests become more comercialised with single species predominating with ideals of economic efficiency little wood is left to rot. Contracters will attempt to use as much of the wood as possible and do not want dead wood to get in the way of machinery.
Incidence:
From what we know of northern Canada, Russia and Poland, at any time up to 60% of the forest trees and bushes would have been dead or dying, providing a habitat for thousands of different kinds of fungi, ferns, flowering plants, insects and other invertebrates, mammals and birds.