| Cottonwood
Range |
dbhg-@comcast.net |
| Aug
08, 2003 16:35 PDT |
ENTS:
The Connecticut River corridor from
Springfield, MA to Hartford, CT holds
great promise to add splendid cottonwoods to my cottonwood
database. Today on a
trip to Hartford, I saw many large specimens that have gone
unnoticed by just
about everyone, including yours truly. They are on the radar
scope and now John
Knuerr, Gary Beluzo, and I are tuned into Populus deltoides. I'm
especially
anxious to add Connecticut trees to the list, not so much
because they
represent a different political entity, but because they are a
little further
south and more under the influence of Long Island Sound. They
grow in a
slightly warmer climate, albeit only marginally so from that of
Springfield,
MA. However, starting from a spot in northern Vermont and
working down to
Biloxi, Miss, it is hard to understand why the cottonwood is
excluded from much
of the central Appalachian corridor. It isn't temperature or
precipitation.
Consider the temp range
| Location |
Jan |
Jul |
Cottonwood |
| St.
Johnsbury, VT |
17 |
69 |
Y |
| White
River Junction,VT |
18 |
69 |
Y |
| Brattleboro,VT |
21 |
71 |
Y |
| Northampton,MA |
22 |
71 |
Y |
| Hartford,CT |
26 |
74 |
Y |
| Bridgeport,CT |
30 |
74 |
Y |
| New
York, NY |
32 |
76 |
Y |
| Boone,
NC |
29 |
68 |
N |
| Asheville,NC |
36 |
74 |
N |
| Black
Mtn,NC |
35 |
72 |
N |
| Knoxville,TN |
38 |
79 |
Y |
| Biloxi,MS
51 |
51 |
82 |
Y |
Appalachian range restrictions are neither from cold or
precipitation.
Bob
|
| More
on Cottonwood Range |
dbhg-@comcast.net |
| Aug
10, 2003 12:25 PDT |
ENTS:
Looking at the conspicuous Appalachian gap in
the east-west and north-south
range of Populus deltoides makes me ever more curious about the
explanation.
Nobody questions the ends of the range, but a gap in the middle?
The gap is not
related to extremes of temperature since cottonwood territory
includes very
cold places like Minnesota, Montana, Saskatchewan, and Alberta.
The range
includes hot regions like south-central Texas. Temperature is
not a factor. Nor
is the Appalacian restriction range based on moisture since the
range of the
cottonwood includes very wet to vary dry climates. The
Appalachian range
restriction doesn't include all the Appalachians since the
species is found in
the Berkshires of Massachusetts and in other northern
Appalachian areas.
Perhaps the range maps are wrong or
perhaps the species is just absent in
upper elevations of the Appalachians. That is a definite
possibility, but if
so, it isn't the temperature component of altitude. If to get
established in
abundance, the cottonwood needs large areas that stay flooded
for considerable
time periods, that would exclude upper elevations in mountainous
terrain where
flooding is brief for obvious reasons. So is does the answer to
the Appalachian
exclusion lie in land form? Or are the range maps simply
outdated, or both
explanations? Lee, any thoughts on the Appalachian restriction?
Anybody?
Bob
|
| Re:
More on Cottonwood Range |
lef |
| Aug
10, 2003 16:10 PDT |
Bob:
Cottonwood does not require flooded areas to survive, but it can
only
compete against other tree species in areas that flood or are
disturbed in
some other way. However, I doubt that the lack of floodplains
would totally
exclude the species, there would still be a few around.
That brings us back to temperature, but a different aspect of
temperature
than you were considering. Cottonwood drops out in northeastern
MN, even
though it grows in areas like North Dakota with winter extremes
just as
low. That is because it is not only winter temperatures that
limit
species. Summer temperatures also limit a lot of tree species.
Cool summers
exclude a lot of species, and that is likely part of the
explanation.
Lee
|
| Re:
The ENTS go marching on |
Lee
E. Frelich |
| Dec
22, 2004 11:26 PST |
Bob:
Sounds like you had a good time teaching people to measure trees
in
Vermont. We could use more heights and Rucker indexes from the
northern
areas. The more latitude we span the better.
Speaking of cold spots, the junction of the Minnesota and
Mississippi
Rivers, which is in a valley below the Minneapolis-St.Paul
International
Airport (where the temperature data you cited came from), is
quite a bit
colder than the plateau the airport is on (in fact the whole
city is quite
a bit colder than the official readings at the airport). Yet, I
keep
finding more 15 and 20' cbh cottonwoods in the relatively wild
forests
lands of the river valley every time I look. I also found one
within
walking distance of my place last week that is probably 16-18'
cbh, but I
didn't measure it since it was -10 with a 40 mph wind when I was
there. You
gotta keep moving under those conditions. If you pause for more
than 3
seconds, you will turn into a pillar of ice.
On the other hand, 150 year old cottonwoods near Lake Michigan
in Chicago
are only 10' cbh, even though winters there are quite mild. As
one moves
inland in Chicago, the cottonwoods get bigger by the mile--about
1 foot cbh
for every mile from Lake Michigan, until they reach the same
15-20' cbh
range as in Minneapolis. My conclusion is that cottonwoods are
not
influenced by winter temperatures, but they have a large
response to summer
temperatures. They grow big as long as the summer is warm and
humid, hence
the 20' cbh cottonwoods in Minneapolis, where daytime
temperatures are
above 80 degrees for several months, and relatively diminutive
cottonwoods
on the Chicago lakefront, where it rarely reaches 80 degrees
during the summer.
Lee
|
| Lee
and Ernie |
Robert
Leverett |
| Dec
22, 2004 13:17 PST |
Lee:
That's fascinating. I was wondering when you
would spawn a plausible
theory on cottonwood growth in the areas where you are finding
the
whoppers. Beyond your explanation for the growth
characteristics, it
sounds to me like you can lay absolute claim to the largest
collection
of cottonwoods in the 15 to 20-foot circumference range. How
many do you
currently have cataloged?
Here are some interesting climate statistics.
Location
Jul Hi Jul Lo Precip
Springfield, MA 85.4 62.9 3.60
Minneapolis, MN 83.0 63.0 4.04
On the surface, it appears that Springfield
and Minneapolis have very
similar climates in July. Other than the severity of
thunderstorms, what
do you suspect is different? What isn't revealed by these
statistics?
Maybe Ernie can weigh in on this one also.
Bob
|
| Re:
Lee and Ernie |
Lee
E. Frelich |
| Dec
22, 2004 14:08 PST |
Bob:
I probably have 25 cottonwoods in the 15 to 20' cbh range, and
there are
still several sites I have heard about that I haven't visited
yet, so I
expect that total to double.
Regarding the climate, we probably have more warm weather in the
spring
than you do out east, although I am not sure that would make a
big
difference. You do seem to have big cottonwoods there, so the
difference
may lie in how much of the right type of floodplain habitat
exists in MA
versus MN and WI. We have several vast floodplains along slow
moving
rivers (a mile or more wide and hundreds of miles long) on the
Minnesota,
Mississippi, and Wisconsin rivers. If you combine that much
habitat with
the right climate, it leads to a lot of big cottonwood trees.
Lee
|
| RE:
Lee and Ernie |
Ernie
Ostuno |
| Dec
22, 2004 22:49 PST |
Bob,
Climate-wise, a good indicator to compare might be "growing
degree
days". These are calculated from daily high and low
temperatures and are
used by agricultural interests in the same manner that
"heating degree
days" are used by energy companies. Generally, the more
growing degree
days during the season, the more plant growth there was
(provided
sufficient moisture was available of course). Here's the
explanation
from the climate prediction center web page on corn growing
degree days:
"A corn growing degree day (GDD) is an index used to
express crop
maturity. The index is computed by subtracting a base
temperature of
50°F from the average of the maximum and minimum temperatures
for the
day. Minimum temperatures less than 50°F are set to 50, and
maximum
temperatures greater than 86°F are set to 86. These
substitutions
indicate that no appreciable growth is detected with
temperatures lower
than 50 or greater than 86."
Now how well this applies to cottonwood trees is debatable, and
there is
the issue of moisture stress (Minneapolis may be a bit wetter in
the
summer than Springfield) but this could be a good overall
indicator of
growing conditions for most plants. Looking at the climate
prediction
center stats:
http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/cdus/degree_days/grodgree.txt
Unfortunately, normals for Minneapolis (MSP) and Hartford (BDL,
the
closest site to Springfield) were not available, but looking at
last
years totals MSP had 2,909 and BDL had 3,195. It's hard to say
what the
departures from normal were at those two sites, but looking at
nearby
sites: Albany, NY had about 100 more GDD than normal and Eau
Claire, WI
had about 60 GDD more than normal. So it seems (as the average
July
temps would indicate) that climatologically, there isn't a big
difference between Springfield and Minneapolis.
Which would point towards habitat as being the more important
variable
here, as Lee indicated.
Ernie
|
| RE:
Lee and Ernie Continued |
Lee
Frelich |
| Dec
23, 2004 08:40 PST |
Bob:
The amount of growth a tree can put on is probably correlated to
growing
degree days within a certain range of other important variables.
For
example, red oak can be severely injured by extreme winter cold
and spend
most of the summer repairing the damage, so that more GDD would
not
necessarily mean more growth as compared to another site with a
cooler
summer, but that does not have extreme cold during the winter.
When Paul
Jost and I saw the red oaks at Muskegon MI, after crossing Lake
Michigan on
the ferry, it was obvious that was the case. Their oaks in MI
grow faster
and get bigger even though they have less GDD than WI, because
there is
less winter injury.
Northern conifers cannot tolerate extreme summer warmth and
dryness, but
they would grow more with more GDD as long as extreme summer
temperatures
were within their tolerance. Winter cold is not a problem for
them, except
for those trees transplanted from the southern edge of their
range to the
northern edge (i.e. a white pine from Cataloochee would have
died last
night in northern MN--minimum at Embarrass, MN last night, which
is near my
Hegman Lake and Kawishiwi white pine stands, was -42).
Lee |
|