Clearcuts & sustainability

Richard Scott rscott at
Thu Oct 15 09:49:57 EST 1998


Thanks for your reply.  It seems your people & my people need to get
together, because even though I have worked in DF forests for over 20
yrs., I have never heard of a Formes annotosum.  Probably the
mycologists & pathologists just don't talk frequently enough.

I have heard of a disease we used to call Fomes annosus (now
Heterobasidion annosus), which I suspect is the same thing--scientific
names do change and perhaps that's what has happened.  Annosus, in the
experience of foresters & pathologists, however, is not as infective
as you suggest and healthy trees can often overcome an attack. It does
spread by root contact and by spores which are released from
honey-colored mushrooms.  Although large stumps do take a long time to
decay, I have never read any literature that suggests infection by
annosus slows the decay process.

Species vary in their susceptibility and the seriousness of the
disease varies by region.  Furthermore, the disease has different
strains, each of which is associated with a specific species of tree,
so that the strain that infects pines is not effective at attacking

Treatment for annosus infected stands depends on whether the stand is
east or west of the Cascade crest, as it is more serious on the east
side.  I have never heard of a hot burn being employed to treat an
infection, although I would not be surprised if it had been tried.  I
also would not expect it to work, because one would have to almost
totally consume the stump and roots, which never happens in fresh cut
stumps--only old stumps which have had a year or more to dry out in a
dry climate.

Since the different strains are associated with different tree
species, we can manage the disease simply by switching conifer
species, rather than going to hardwoods.

Again, thanks for your reply.  See you at Tree School?

Dick Scott

dwheeler at wrote:

>In article <nS9V1.1634$Gq.1807 at>,
>  rscott at wrote:
>> Can someone give me a brief rundown on the environmentalists' claim
>> that clearcutting is an unsustainable practice?  I would  like to know
>> the reasoning and the factual basis for this assertion.
>> Dick Scott

>I don't know that I can give a claim from an environmentalists' viewpoint,
>but certainly I can give one from a mycological view: clearcutting provides a
>lot of material for growing Fomes annotosum, aka Douglas fir root rot. Once
>infected, wood degrades much more slowly than with other saprophytic fungi.
>Degradation of a single 3 foot diameter chunk of wood may take centuries (in
>other words, no one really knows how long). Until the chunk has become
>_totally_ consumed, it acts as a potential inoculation site to infect nearby
>growing conifers, and eventually kills them. Almost all conifers are
>susceptible to this fungus.

>Ironically, the only known way of controlling the spread of the fungus is to
>clearcut, following by a very hot slashburn. Even afterwards, the site should
>be planted to hardwoods, which are not affected by the fungus.

>If an infected site is clearcut but not burnt, the debris is not sterilized,
>and Fomes annotosum often comes in. A single sporocarp (fungal fruiting) can
>produce millions, if not billions of spores. These are wafted about on the
>air, along with other fungal spores. The average breath inhaled by a human
>contains about 10,000 fungal spores.

>It's pretty obvious that clearcutting is an excellent method to provide food
>for this fungus, and ensure its continued health.

>There may be a way out, but it hasn't been tested. It has been noted that,
>with live trees associated with Tuber gibbosum (Oregon White truffle), the
>truffle seems to act as a fungal prophylactic, disallowing Fomes annotosum to
>infect Douglas fir roots. While this has been observed, it has not been
>tested to my knowledge, because most people don't know how to grow Tuber

>BTW, Tuber gibbosum is spread most quickly by a small noctural bird called
>the Northern Spotted owl, which dines on voles and squirrels, which in turn
>eat mostly truffles. Clearcuts over 100 yards wide allow Great Horned owls to
>attack and kill Northern Spotted owls. But Great Horned owls seldom catch
>voles from old-growth forests, and thus cannot effectively spread truffle
>spores from those areas.

>As trees mature, there appears to be a succession of mycorrhizal fungi.

>Without mycorrhizal fungi, neither plants nor people would exist long on

>Daniel B. Wheeler

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