The Ecosystem Value of Dead Wood

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A long-term study log decomposition at the H.J. Andrews LTER site, planned to last 200 years and now beginning its third decade, is yielding valuable information about the ecological functions of dead wood. This information is having profound impacts on both the scientific understanding as well as the management of forest ecosystems.
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Traditionally dead wood has been considered a wasted resource and a hazard in forested landscapes that needed to be eliminated. This all changed starting in the 1970s when Andrews scientists began to examine the many roles dead wood played in forests and streams. This included a wide range of ecological and geomorphic functions including as a habitat and food source for many terrestrial and aquatic species; seedbeds for plants (including trees); a store and source of water, energy, carbon, and nutrients; and as an influential geomorphic agent that controlled stream structure and function. These findings were summarized in a widely cited and highly influential publication (Harmon et al. 1986) based on Andrews science that set the stage for an entirely new field of study. Since that time scientific studies on this topic have greatly expanded globally and dead wood is a key feature of understanding forest biodiversity and carbon cycling as well as how riparian systems function.

Given the many functional roles of dead wood in forests and streams, in the 1980s Andrews scientists and forest managers began a collaboration to see how a system of dead wood removal could be replaced by one of restoration and maintenance. These efforts lead to management plans and guidelines that greatly modified the management of forested landscapes. The ecological values of dead wood in forests and streams strongly influenced the forest management practices and development of riparian reserves in the Northwest Forest Plan, which as influenced forest management throughout North America. While increasing ecological values, these actions also reduced economic costs. For example, ending the practice of removing unmerchantable dead wood saved tens of millions of dollars per year in Pacific Northwest National Forests.

These key science and management findings have strongly influenced how forests and their associated aquatic systems are managed today (Harmon 2001). While the initial research focused on old-growth forests within the Pacific Northwest, management of dead wood in forests throughout the globe now focuses on how this structure as a key biological legacies in forests of all ages. Research at the H.J. Andrews led to an international synthesis of research on large wood in aquatic ecosystems and has stimulated global awareness of the role of wood in ecosystems (Gregory et al. 2003). Many stream habitat restoration efforts focus on the reintroduction and maintenance of large pieces of dead wood in channels to create desirable habitat for target species such as salmon. Collaborative efforts with international scientists highlighted fundamental differences in social perceptions of the ecological values of wood in ecosystems and major discrepancies between science and social management decisions.

Emerging policy issues center on the role of dead wood as a carbon store versus as a source of bioenergy. The rationale for the latter management objective harkens back to dead wood as a wasted resource and it remains to be seen whether the other ecosystem functions of this material, including as a carbon store, will influence forest-based biofuel polices.

For further reading: 
Harmon, M. E. 2001. Moving towards a new paradigm for dead wood management. Ecological Bulletins (Sweden) 49:269-278.
Harmon, M. E., J. F. Franklin, F. J. Swanson, P. Sollins, J. D. Lattin, N H. Anderson, S. V. Gregory, S. P. Cline, N. G. Aumen, J. R. Sedell, G. W. Lienkaemper, K. Cromack, Jr., and K.W. Cummins. 1986. The ecology of coarse woody debris in temperate ecosystems. Recent Advances in Ecological Research 15: 133 302. (reprinted in Advances in Ecological Research Classic Papers Volume 34 in 2004).
Gregory, S.V., K.L. Boyer, and A.M. Gurnell, editors. 2003. The ecology and management of wood in world rivers. American Fisheries Society, Symposium 37, Bethesda, Maryland.
For further information: 
Dr. Mark Harmon
Dr. Stan Gregory
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