It was presented on March 4, 2016 at the University of Oregon as part of the 34th Annual Public Interest Environmental Law Conference (PIELC).
[D]ying and dead wood provides one of the two or three greatest resources for animal species in a natural forest … if fallen timber and slightly decayed trees are removed the whole system is gravely impoverished of perhaps more than a fifth of its fauna.
–Charles S. Elton, The Pattern of Animal Communities, 1966
I recently attended one day of the four day long Public Interest Environmental Law Conference (PIELC) held at the University of Oregon. One panel in particular titled “Rethinking Forest Health” serves as the inspiration for this post. The panel included George Wuerthner. The purpose of the panel was to reconsider what it means for a forest to be in good health. Wuerthner’s portion of the presentation focused largely on the need for dead trees and down wood in a healthy forest—a requirement no less vital to forest health, according to Wuerthner, than living trees.
I was most interested in the many ways that wildlife—including birds, mammals, reptiles, amphibians, and others—depend on the presence of dead trees. Below are some examples drawn from the available scientific and technical literature (bold emphasis on species names has been added):
The above examples focus exclusively on what dead trees and down wood—commonly referred to as “coarse woody debris” in the relevant literature—provide to animal species. The list could be expanded with both by listing additional benefits to animals but also by listing benefits to plant life or things such as preventing erosion and enriching the soil.
In intensely managed forests—glorified tree farms—dead wood is often nearly absent wheras “[i]n naturally dynamic forests dead wood is a dominating feature and makes up 30-40% of the total wood volume.” After a single logging event, dead wood may be reduced to 20 percent and after several logging rotations, dead wood may be a mere one percent of the total volume of wood that remains. (Source)
Current logging practices are often defended by pointing out that a clearcut, for example, might sometimes appear to mimic large scale fires. The significant difference in these cases is that even intense fires tend to consume less than 10 percent of available wood whereas clearcuts can remove upwards of 95 percent of available wood. Wuerthner describes this down wood as a “biological legacy” in contrast to the timber industry which often characterizes it as “wasted” or “squandered”.
During the question and answer portion of the panel that inspired this post, Wuerthner was asked what this information meant for the prospect of “sustainable forestry”. Admitting that his answer was likely to be “unsatisfying” and imprecise, he suggested that any rate of harvesting timber that was economically viable was almost sure to have exceeded a sustainable level.
Perhaps an alarming conclusion for those with an almost religious faith in the idea that industry and nature can co-exist; less alarming for those such as Aldo Leopold who, albeit resorting to a mechanical metaphor, asked: “who but a fool would discard seemingly useless parts? To keep every cog and wheel is the first rule of intelligent tinkering.”
Wild Fire: A Century of Failed Forest Policy by George Wuerthner
Proceedings of the Symposium on the Ecology and Management of Dead Wood in Western Forests (2002)
“The Seen and Unseen World of the Fallen Tree”
“All Treesearch publications were written or produced by Forest Service personnel and are in the public domain.”