Most people recognize the role living trees play in ecosystems. As individuals they provide shade and shelter, together they form the familiar landscape of the forest.
Of less common knowledge are the services that trees provide after they die. Standing dead trees offer forage and nesting habitat, fallen trunks enrich the forest floor, and woody debris carves out new niches in aquatic environments.
When woodpeckers feed on the insects in standing dead trees, they leave behind holes. Cavity-dwelling animals that are unable to excavate their own homes, such as chickadees and bluebirds, turn these holes into homes.
Branches that fall off dead trees provide nest material for hawks, eagles, and other large birds—while smaller birds and mammals use twigs to create nests and dens.
Dead trees can stand for up to 40 years before falling. When trees fall into streams, they can transform running water into stable, slow-moving habitat.
On the ground, rotting wood provides nursery habitat for seedlings. Pathogenic soil fungi, which attack and kill young seedlings, are unable to survive on dead wood.
Microorganisms break down dead wood, taking up nutrients that would otherwise be washed out of the forest. These nutrients are returned to the soil when invertebrates, such as slugs and millipedes, feed on decaying wood. These animals are a rich food source for reptiles, amphibians, birds, and small mammals.
The next time you feel the urge to clean up your yard or woodlot, leave some dead wood behind. You will reap the reward of richer soil while increasing resident biodiversity.
Photo, taken on May 6, 2010, courtesy of Christopher Sessums via Flickr.