[obol] (Off topic somewhat) Habitat notes

[Bruce Newhouse]

Greg posted some thoughtful comments about habitat, to which I would 
like to add.
/
"Might I heretically suggest that blackberries taking over former 
grasslands or other habitats is less a problem with the blackberries 
than it is a result of strict fire suppression."/

If I understand the intent of that comment correctly, I agree.  It isn't 
the blackberry's fault.

/"Grasslands in the Willamette Valley are almost totally artificial 
(farming and grazing).  Left alone, even without blackberries, the 
grasses will give way to roses, hawthorns, scotch broom, and other 
brushy plants within a dozen years."/

I second that comment.  I spend a lot of time walking in them doing 
wetland delineations, botanical inventories, and bird and butterfly 
inventories, and native woody encroachment is a very serious problem.  
(The paragraph above contains some native and some exotic invasive 
species.)  Native tree encroachment also is a huge problem: Douglas-fir 
in uplands and Oregon ash in wetlands, for example.  Encroachment by all 
these tree and shrub species converts the grassland habitats so critical 
for our grassland species in decline, to (using uplands as an example) 
coniferous forest habitat that is very, very common and widespread.

/"If low-heat fires come through every few years then an oak stand may
become established over these brushy plants."

/Maybe.  There are a lot of other variables at play with vegetation, 
soil and soil moisture, fuel buildup, proximity of seed source, slope 
and aspect, etc.  For a look at what the Willamette Valley looked like 
after several thousand years of indigenous people's management before 
EuroAmerican settlement, check out the 1850 "presettlement vegetation" 
map on the PNW Ecosystem Research Consortium web site at OSU. There was 
a lot of upland prairie out there, and lots of savanna, and only tiny 
traces are left.  (If you aren't familiar with definitions of those 
terms, "prairies" have large treeless areas with occasional, scattered 
trees, and "savannas" have widely spaced trees, but with mostly prairie 
species growing between (lots of light).  "Woodlands" are denser, and 
"forests" are the most dense.)/
/
/"Without fire the blackberries will give way soon to Douglas-fir--the 
climax
species--even on the Valley floor. Actually, in my area, grasslands (farms)
give way to blackberries only for a few months before they are then 
succeeded
by the ultimate climax species--strip malls and condominiums. Personally,
I prefer the blackberries, as I  think that even nasty ole blackberries 
are better
for birds than parking lots."/

Well, I have to disagree with a couple of things here. While fire may be 
a "tool of choice" in many management situations, other tools may be 
required in other situations (and likely will not yield the same result 
as burning).  I'd also like to comment on the climax species mentioned.  
Generally, a climax tree species has to be able to reproduce under it's 
own shade, and Douglas fir cannot (which is why forester's prefer to 
clearcut it, so new stands can be replanted in full sun; and why they 
drop their lower branches in closed stands).  According to Franklin and 
Dyrness in their classic, Natural Vegetation of Oregon and Washington, 
grand fir would be the likely low elevation climax in NW Oregon in most 
upland areas, as it can reproduce under itself.  There are way many 
sites where that would not occur, and in general, because of 
disturbances setting back succession, climax ecosystems (at least in 
this area) are often referred to as "hypothetical"  or "theoretical."  I 
have heard botanist's mention that Armenian blackberry possibly may be 
considered a climax on some sites as nothing else can reproduce under 
it.  (Of course, kudzu hasn't become established here yet, so that may 
change.....)

/"For an overview of plant succession see:
http://www.cnr.uidaho.edu/for270/powerpoint/Succession/successn_files/frame.htm"/

I was interested in seeing that, but only succeeded in loading in a 
blank frame.  Anyone else get it to work?

Thanks again, Greg for your comments.  I look forward to more.

Habitat is where it's at: can't have birds without it!

Best,

Bruce Newhouse in Eugene
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