18, 2005 22:52 PST
Well, I haven't been searching the internet on cottonwoods, but
I can now
tell you about what happens when they grow fast at Phantom
Ranch, down in
Grand Canyon alongside Bright Angel Creek. Last summer, myself
and a forest
pathologist evaluated the cottonwoods at Phantom for
identified 33 trees that either needed pruning or removal
we went down to Phantom Ranch. Every tree we treated had
some more than we anticipated, and some where we hadn't
These trees were planted in two waves, the first in 1920s at the
inception, and the second in 1930s with the Harvey
of the 'dude ranch' now known as Phantom Ranch. Some 75 and 85
they clearly are reaching the far end of their time here on
normally a problem, but virtually all of them were planted where
create shade for guests and historic structures...and habitat
eagles and other denizens of the Park.
Not being an arborist by trade or training, I would welcome
input from any
of the arborists who grace this listserve...replacing
cottonwoods with a
hardier more windfirm species that still provides quick shade
AND is native
to the Park, has been the challenge.
20, 2005 22:22 PST
I am curious about the time frame in which the cottonwoods will
need to be
replaced? Have you ever been to McKittrick
Canyon in Guadalupe National
Park in Texas? In the park are some of the most spectacular fall
from an isolated pocket of maples growing there.
I wonder how much genetic drift has taken place in this isolated
from the main body of the tree population? It is likely that a
situation has occurred with the tree and shrub populations
native to the
floor of the canyon.
First I would look at historical records of the early
expeditions down the
canyon, John Wesley Powell kept notes during both his first and
expedition down the canyon. What trees did he and other early
find before the landscape was altered by ranching, and before
species arrived from elsewhere? What do some of the other
What trees are shown in the photographs of Timothy O'Sullivan?
lived at the bottom of the canyon before the arrival of
settlers? Or even
before the native Americans? Once you knew what species were
at least commonly present in the pre-settlement days, then you
one that provided the best shade for structure and adequate wind
Journal of Powell's second trip can be found at this address:
From what I read cottonwoods were the most commonly mentioned
tree in the
canyon. Perhaps the problem is that the cottonwoods planted in
were not native to the canyon itself?
p. 94 (Bright Angel Canyon) Early in the afternoon, we discover
entering from the north, a clear, beautiful creek, coming down
gorgeous red canon. We
land, and camp on a sand beach, above its mouth, under a great,
tree, with willow shaped leaves.
p. 100 Our way to day is again through marble walls. Now and
then we pass, for a short distance, through patches of granite,
thrust, up into the limestone. At one of these places we have to
another portage, and, taking advantage of the delay, I go up a
to the north, wading it all the way, sometimes having to plunge
in to my
neck; in other places being compelled to swim across little
basins that have
been excavated at the foot of the falls. Along its course are
and springs gushing out from the rocks on either side. Sometimes
tree grows over the water.
I would like to see trees originally native to the canyon. Maybe
cottonwoods native to the canyon rather than from elsewhere. If
time, it might be better to transplant specimens of these
locations elsewhere in the canyon. These should be locations
populations are sufficient that it will not strain the local
there is time, seedlings could be grown from local seed.
The second option would be to replace the cottonwoods with
such as willow, originally native to the canyon, but from
sources from areas outside of the canyon. There is some concern
might not thrive as the local original trees may have become
to growing on the canyon floor over time than plants from other
Trees from more southerly areas when transplanted here in
tend to bud and flower earlier than do local native trees.
Another consideration might be that this age range is as
long as a typical
cottonwood will grow in the area without problems given the
environmental conditions. Certainly the flood regime of the
has changed dramatically with the Glen Canyon Dam. Trees are
by pollution and ozone levels higher than pre-industrial days. I
think this is the case, but in any marginal situation, even
in climate can affect species viability.
Grand Canyon Cottonwoods
21, 2005 18:22 PST
Most of the studies on cottonwoods in the Southwest don't wax
optimistic on longevity...The conditions that make them grow
out here want shade NOW) don't lend the tree much in the way of
(unlike say, an oak, which the wider the annual ring the
The cottonwoods at Phantom Ranch are on a side tributary (Bright
Creek). Bright Angel Creek still retains a "natural"
flood regime. There
certainly are cottonwoods along the Colorado, but the
there generally prevents anything getting rooted for long.
quality, we have a long running air quality program and the
records of our
air quality are fairly extensive, both in the canyon and on the
monitor regional power generating plants.
The effects of these on a species not known for its longevity
could have a
"disproportionate" effect, although to date, no one
has yet done a study to
Tomorrow, we go down to Indian Garden to prune/remove a half
trees"...3 miles down the trail, 3000 feet elevation
loss...better shift off
my low carb diet and consume some carbs!
Grand Canyon Cottonwoods
21, 2005 18:49 PST
I have done some preliminary research on the role of cottonwoods
historically in the Southwest, and in the Canyon in particular.
accounts are new to me, and I'm sure I have much more to peruse.
We are in the initial stages of putting together an EIS for our
program, and reference conditions will be fully
publications recording the 1910 to 1930's are fascinating
were employed to carry the suspension cables for the 1920s
bridge, down a trail, with individuals every 12 foot
"winding" down the
trail...photographs of the time show short, freshly planted
with none of any size in view. To date the source of their genes
presumed to be imported from outside the immediate region, but
one of the
methods of propagation in sufficiently moist sandy soils was to
branch off a nearby cottonwood into the selected site.
I do recall, from my role in the research permit review process,
proposed to investigate the gene source of Canyon cottonwoods,
but that was
just last spring, and results are still forthcoming.
We have been looking at velvet ash and boxelder as they are both
the region and the canyon, at different locations. However,
velvet ash is
slow growing and boxelders share a lack of windfirmness with
The Park has with the cottonwoods a precedent in importing shade
outside regions. Given choices, we'd prefer not to follow that
but our missions sometimes conflict...those who have been down
June-August will vote shade and shade NOW...for more than it
possible, these can be life or death decisions. Last July, I
left the rim
at 5PM, and when I checked the thermometer at Phantom Ranch upon
at 11PM at night, it was 109 degrees...
Thanks for the literature tips, I look forward to reviewing them