Eric wrote:
>Interesting. I'm sure it varies a lot depending on many factors (temp.,
>slope, soil, other species, etc.), but in my area (Coastal Range, just
>north of San Francisco, California), the Douglas Fir tend to grow into
>forests on the (shadier, cooler, wetter) north slopes, growing up through a
>mixed forest of Oaks, Madrone and Bay (which had taken over areas of
>Manzanita, Chapparel, brushy stuff).
Yes, this relationship between plants and different growing conditions
leads to a couple of design rules and also to some interesting facts.
The design rules i see are:
1. Designs are site specific and communications about a
designs often need local verification of the facts.
2. General rules and literature about design components
need to be adjusted to fit a site.
The interesting fact about Douglas fir is that the seeds are
programmed to grow at one specific elevation. So, when we
say Douglas fir we are talking about a whole array of
trees. This gets even more interesting if the foresters i've
talked to are right. They claim that a seed from an old growth
Douglas fir does not produce the same tree. Lumber mills claim
that the wood from an old growth is different from the wood of
a second growth. Another interesting view is that we can't
clone an old growth forest because the plants have changed and
so has other factors. Once you cut an old growth down it is
gone forever.
Here is a useful table of growing factors for trees in Oregon's
Willamette valley (large numbers = increased hardness):
Shade Drought Frost
Tolerance Tolerance Tolerance
Douglas fir 2 3 4
Ponderosa Pine 1 5 5
Grand fir 4 2 3
Noble fir 3 2 2
W. Red Cedar 5 1 2
W. Hemlock 5 1 1
Incense cedar 2 5 3
O. White Oak 2 5 5
Bigleaf Maple 3 3
Red Alder 1 1 2
Cottonwood 1 1
Oregon Ash 3 2 5
Chinkapin 3 4
Madrone 2 5
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Jeff Owens ([EMAIL PROTECTED]) Zone 6-7
Underground house, solar energy, reduced consumption, no TV
