The value of "dead" trees

In a local park here, I often see birds like woodpeckers visiting snags or dead trees, looking for insects therein. The holes woodpeckers drill get occupied by them and other bird species across seasons. Although these trees are dead or dying they continue to provide. The Urban Forest Management Strategy should incorporate the role of "dead" trees. They should be allowed to remain if possible. If they have to be removed they should be installed elsewhere so that their benefit continues.