Wildlife needs dead trees

From Wildlife & Trees in British Columbia:

It is important to remember that, under natural conditions, a tree remains part of the forest ecosystem long after its death. It's rate of decay varies according to the species, cause of death, climate and other factors. If left undisturbed by humans, a dead tree may remain standing in the forest for up to half the time it stood while alive. A tree's ecological importance continues as it breaks apart and falls to the ground or after it topples, and eventually all its nutrients are cycled back into the soil to be taken up by new plants.