Subject: more on spotted owl old growth, from a researcher
Date: May 3 12:13:59 1995
From: Erran_Seaman at nps.gov - Erran_Seaman at nps.gov


I have some further comments about spotted owls and old growth. I work for
the National Biological Service at Olympic National Park, and have been
studying spotted owls here for 3 years.

I agree with Keith Swindle's comments. Much of the problem is generated
semantically because we encompass many things in the terms "second growth"
and "old growth". As Keith said, the structural complexity (rather than the
age) of the stand is most important for spotted owls.

The reasons for the importance of structural complexity are the subject of
much conjecture at this point. Forest structure may be important in
providing at least: thermal cover; hunting perches; and nest structures for
spotted owls. In addition, it provides habitat for prey species
(principally nest cavities for flying squirrels).

Keith emphasized the fact that redwood forests can develop structural
complexity very quickly, and in fact this is where most of the controversy
has been generated from. Greg Easterbrook's article in the New Republic
(and the book it was excerpted from) has been widely circulated. Much of
his argument is based on taking facts from the redwood area and maliciously
applying them to Washington and Oregon (where they do not correctly apply).

In Washington and Oregon, the only way to maintain structural complexity
among young stands is to leave it there (i.e. don't cut or burn it all).
Wildfires generally DO leave pockets of old trees (particularly in the
drainages where conditions are moister) when they burn. Clear-cuts rarely
leave any large timber behind. Contrary to the claims of the timber
industry, clear-cuts are NOT exactly like wildfires!

In addition to leaving forest structure, leaving the soil intact may be very
important. The fungi in the soil are an important food source for flying
squirrels, and are important for tree growth. Clear-cut methods (and some
"shelterwood" methods) generally destroy the soil fungi and result in very
poor owl habitat. Wildfire leaves the soil intact, allowing quicker
regeneration of owl habitat. Furthermore, leaving dead trees on the ground
can provide valuable substrate for other fungi, and habitat for voles
(other important owl prey species).

There is no doubt about the fact that some spotted owls live in second
growth, some even in the poor quality second growth that results from
logging. However, reproductive success decreases as the amount of
old-growth around an owl site decreases, and owls in vast tracts of second
growth will have such low reproduction (and probably low adult survival)
that they could not maintain a stable population in such habitat.

Erran Seaman