Deadwood, Take a Bow

A Changing View

"Come to me," says the site, "Design a habitat, buy plants, restore my ecological structure and function, and let me develop." We have heard this song many times and it is the soundtrack for our actions. But we rarely hear, "Find deadwood and scattered it on the ground." The siren's call is incomplete.

A long series of studies has shown that deadwood, standing or fallen (coarse woody debris = "CWD" in academic circles), is integral to habitats' long-term health. Our culture commonly uses the phrase "dead wood" as a metaphor for uselessness, for stagnation where there once was vitality. In restoration ecology, a different stance is more appropriate as we have learned the many critical roles that deadwood plays to sustain and prolong the fate of living habitats.

Values, Long Obscured

Rotting wood plays many roles as the specific habitat for so many species. Sometimes it is a site for fungi and invertebrates who use deadwood as critical niche space. These species then drive higher trophic level resources, including food for many animals who search for insects and other critters in rotting wood. The wood also can serve as nesting, resting, and hiding places for many vertebrates. In fact, the diminution of standing deadwood has directly led to population crashes of some hole-nesting animals. The rarity of red-cockaded woodpeckers in the American Southeast may be the most known example.

The arthropods and fungi that reside in deadwood do more than just break down the fibers that become elements in soil creation and influence the forests carbon budget and nutrient recycling rates. Many deadwood dwellers, saproxylic insects, are pollinators. These can include beetles, flies, bees, and wasps. Some of these also dwell in fungi whose brackets serve as domiciles. Similar functions occur in streams where deadwood serves as protection for juvenile fish and as habitat for many aquatic invertebrates. (The book Trout Stream Therapy is a charming summary of these services.) Accumulations of deadwood also modify hydraulic patterns and are important to slow and store water flows which then create wet meadows and improve soil moisture for surrounding woodlands. Direct and indirect advantages to aquatic habitats are blessings from recently deceased trees.

Rotting wood also serves as a microsite for seedlings and this function can be significant in certain forest stands. Rotting wood is moist, of course, high in organic matter, and devoid of competition of established roots from the surrounding plant community. In some conifer forests, a high percentage of seedlings are found preferentially on rotting logs. For ant-dispersed plant species, many seeds and subsequent seedlings appear on rotting logs, where the ant workers nests are found.

The age of the rotting log can be associated with the number of seedlings, showing the subtlety of the interaction between deceased trees and the next woodland generation. Restoration ecology always considers the species identity and proportions of plants to be added to a project site. Extending this concern to the age and species identity of the wood on the ground is a daunting complexity.

Time will help, as accumulation of deadwood and its slow degradation will add a variety of microsites upon which seedlings can thrive. In natural stands, the accumulation of deadwood is episodic, advancing after storms, infestations, and seasonal droughts. This dynamic then drives the life history parameters of those plants, fungi, and animals which use the deadwood resource. We sometimes think of natural processes as continuous and predictable, what we call the Walt Disney Theory of Nature. But the fits and starts of disturbances are natural and the availability of the deadwood resource for all other species also ebbs and rises with physical and biotic change.

Design and Management Challenges

We are convinced that deadwood is part of a winning hand in the game of restoration ecology. We now tell the landscape architect and the contractor that we want deadwood on the ground and maybe some dead trees standing. What comes next? You get a tsunami of questions, following the blank if not bemused stare. How much? What size? What state of decay? What density? What location? How long should each piece be? What species...