Applegater Fall 2012 17
Forest maintenance work leads to questions
bY SAnDY ShAffER
It’s been 10 years since my husband
and I took advantage of fuel reduction
grants and had almost all of our forested
property thinned. This spring as I was
pruning, mowing, weed whacking and
such in preparation for fire season, I
noticed that too many of our stands
had closed up, and the ladder fuels were
plentiful.
Maybe it’s because we were short on
stacked firewood, or maybe because we
haven’t had a fire out in this part of the
Applegate in a decade, but I realized it
was time to do some major thinning! My
husband and I feel that protecting our
trees from wildfire is just as important as
protecting our home.
So out came the blue ribbon to mark
trees for removal this fall. Sometimes I
found it easy to tag a tree, but much of the
time I wasn’t sure how to decide between
two perfectly healthy trees of different
species. I realized that while I’ve learned
a lot about defensible space over the years,
when it came to trees and fire, I had more
questions then answers! So I called on
our local OSU Extension forester, Max
Bennett, for some advice on how to decide
which types of trees I should cut and which
I should leave.
Our 20-acre parcel here in the
Applegate is basically a hilltop, so that
gives us a 360-degree changing aspect.
Consequently, we are lucky to have four
conifer species (ponderosa pine, Douglas
fir, sugar pine and incense cedar) and three
species of hardwoods (Pacific madrone,
Oregon white oak and black oak) on
our property. It’s fun (and challenging)
to manage this mix of species, and I like
to maintain a good balance for wildlife
habitat and stand resilience, as well as for
our firewood supply.
My questions for Max mainly revolved
around the fire resilience of these seven
various tree species. (But first, a quick
clarification on the difference between
fire resistance and fire resilience, because
they do have “practical implications”
per Max. “Resistance means the ability
to resist change from a disturbance like
fire. A ponderosa pine is resistant to fire.
Resilience means the ability to return to
the original state after the disturbance.
Madrone is pretty resilient to fire, but
not very resistant.” So resistance means
surviving a fire, and resilience means being
able to bounce back from fire, usually by
resprouting.)
So here are my questions, with Max’s
responses in italics:
Q1: If a ground fire were to come
through my mixed stands, how would
these seven species fare with a scorching
of the bark?
A1: Fire kills trees by killing the
cambium layer just underneath the bark
near the base of the tree, and by killing
leaves (needles) and buds. Death can result
from either one of these, but usually it’s a
combination of the two. Trees with thicker
bark are more resistant to cambial damage.
Trees with larger buds and longer needles
are more resistant to crown scorch. Of the
trees listed, ponderosa pine is the most fire-
resistant. It has thick bark and can survive
surface fires at the sapling/pole stage (a few
inches in diameter). Its large buds, long
needles (which help protect the buds) and
elevated crown make it less vulnerable to
scorch. Douglas fir is the next most fire-
resistant species. When small/young, it is
more vulnerable to cambial damage than
pine, but old-growth Douglas fir trees have
very thick bark and are just as, or perhaps
even more, fire-resistant than ponderosa pine.
Sugar pine and incense cedar have thinner
bark and are more vulnerable to fire than
pine and Douglas fir. Of the hardwoods,
Oregon white oak is the most fire-resistant,
California black oak is in the middle, and
madrone is least fire-resistant. Of course, the
hardwoods sprout right back after fire, while
local conifers lack that ability. (See photo,
top right.)
Q2: Does this depend upon the size
of the tree—are smaller trees always more
susceptible to scorched bark?
A2: Yes, smaller trees are generally
more susceptible to bark scorch and cambial
damage. The bigger the tree, the thicker the
bark. Some trees, such as pine, can survive
fires at relatively small sizes while others must
grow much larger to attain the same degree
of fire-resistance. (See photo, bottom right.)
Q3: So, in general, how would you
rank these seven species for fire resistance?
A3: Here’s a table summarizing fire-
resistance of the species and the size/age at
which they attain medium to high fire-
resistance.
Fire-resistance
Species
Size
at maturity
Ponderosa pine
Douglas fir
Sugar pine
Incense cedar
Black oak
White oak
Madrone
Sapling/pole
Pole/mature
Mature
Mature
Mature
Pole
None
High
High
Medium
Medium
Low/medium
Medium
Low
Q4: Which of these seven species are
the most flammable?
A4: Conifers are generally more
flammable than hardwoods due to the chemical
compounds in needles that burn readily when
ignited. Differences in the
flammability of the foliage
between individual conifer
species are less important
than the density of foliage
and how close the branches
are to the ground. (So keep
pruning up those branches!)
Deciduous hardwoods
are less flammable, because
their leaves do not contain
those types of resins that
conifer do.
Q5: If I were
choosing between one
of the three hardwoods
Pacific madrones (right) peel off a thin layer of their bark each
year, unlike thick ponderosa pine bark (left).
to keep near my house,
which would be safer and
more fire-resistant?
A5: Choosing among
the hardwoods when close
to the house, I’d prefer
to have an oak, all other
things equal. Madrone
foliage (live on the tree and
dead on the ground) seems
a little more flammable,
its bark sheds, and its
habit of dropping leaves
in the summer make it
a maintenance headache
near the house.
Q6: Which of
This old white oak (left) has a much better chance of surviving
these seven species can
a ground fire than the smaller oak saplings (right).
withstand low water years
ribbon! You know, private landowners
or a drought best?
A6: The species in order of drought don’t need to do this alone. There are tons
of resources across our valley to help us
tolerance, from highest to lowest, are:
out, so use them! The more acres being
Oregon white oak
managed, the better for all of our lands
California black oak
here in the Applegate. (FYI: Max and his
Ponderosa pine
colleague Steve Fitzgerald have an article
Incense cedar and Pacific madrone
on page 16 on how to thin stands for
Douglas fir
optimum management—check it out.)
Sugar pine
Well, I hope that these questions
Sandy Shaffer
and answers have helped some of you
Landowner/
a bit in your forest-stand management
Applegate Fire Plan Coordinator
decisions. Thanks to Max, I feel a lot more
sassyoneOR@q.com
comfortable walking around with my blue
“A
banker is a fellow who lends you his umbrella when the
sun is shining and wants it back the minute it begins to rain.”
—Clarence Darrow