| Re:
Trees northern range limit |
lef |
| Jan
31, 2004 16:21 PST |
ENTS:
The weather this last week in MN presents an exciting
opportunity to see
how tree species northern range limits work. Reports of
incredible
temperatures have been coming in all week, including -43 at
Embarass, -44
at Grand Forks, -45 at Park Rapids and -47 at Cook, all in
northern MN (and
not including wind chill, which was down in the -60 degree
range). Daytime
highs have been -20 to -25.
Several species of trees, including red maple, sugar maple, and
red oak,
have expanded their range in northern MN in the last few years,
and/or
individuals that were shrubs that died back to the ground every
year have
gown up into full sized trees, taking advantage of the last 5
mild winters
in a row. Minus 40 to -47 are the critical temperatures for
cambial death
for these species. I can't wait to see if these trees will now
die back and
become shrubs again, making way for the more appropriate species
like black
spruce and red pine.
In my home city of Minneapolis, which is in the near-tropical
banana belt
of southern MN, temperatures this week ranged from a low of -24
to daytime
highs of -4 to -8. Although these temperatures will not affect
red and
sugar maple or red oak (unless the seed source was from some
place like
Indiana), they should cause red mulberry and catalpa to die
back, since
they are members of another set of species less tolerant of cold
temperatures. It will also be interesting to see if the new
varieties of
red bud and magnolia recently introduced in Minneapolis (which
are supposed
to be cold tolerant) will survive.
Note that a lot of species have their northern range limit set
by cool
summer temperatures, since there are areas along the northern
range limit
of most species where winters do not get very cold, and/or the
species have
a -60 to -70 tolerance for winter minimum temperatures that is
rarely
reached even in regions with cold winters (e.g. white pine, red
pine, paper
birch, black spruce, balsam fir, white cedar).
Lee
|
| Re:
Trees northern range limit |
dbhg-@comcast.net |
| Jan
31, 2004 18:26 PST |
Lee:
It is interesting that of teh species you
named that have cold tolerances down to -60 or lower, white pine
is a member. The species is truly remarkable. Other than height,
do you know of another other physical attribute of Pinus strobus
that puts in into a very select species grouping?
Bob
|
| Re:
Trees northern range limit |
lef |
| Feb
01, 2004 15:19 PST |
Bob:
White pine is unique in it tolerance of all soil types from
swamps to bare
rock, its tolerance of different temperatures, its height (and
ability to
adjust its height to soil and climate), its crown form and how
many
different shapes it can take. It is also the most shade tolerant
among the
pines, and can withstand shade suppression to a surprising
extent, unlike
other pines. This species apparently has lots of genetic
variability
compared to other pines, and that allows it to adapt to many
different
environments. Although, note that white pine from NC and
probably MA
cannot survive in northern MN, since those trees have not had to
adapt to
temperatures of -60.
Lee
|
| White
pine adaptability |
Robert
Leverett |
| Feb
04, 2004 13:08 PST |
Lee:
Do you know if there are discernable characteristics of the wood
or
changes in cellular structure that can be observed under a
microscope
that distinguish cold-adapted white pine from those growing in
lesser
extremes?
Bob
|
| Re:
White pine adaptability |
greentreedoctor |
| Feb
05, 2004 03:34 PST |
| Re:
White pine adaptability |
Lee
E. Frelich |
| Feb
05, 2004 06:29 PST |
Bob:
The visible changes that I know of are shorter needles, longer
needle life
span, more densely clustered branches (the bonsai look) and
reddish bark in
cold climates where temperatures attain -40 or lower. Their
needles also
fold inwards towards twigs and clasp the twigs tightly during
extreme cold
spells, minimizing surface area of needles exposed to cold air,
although
this happens at temperatures of 0 degrees F. I can't find any
mention of
cellular changes visible under a microscope in the scientific
literature,
although there is slightly less lignin in the wood of northern
trees.
Other species of pines that have been studied in cold climates
have extreme
drought tolerance, ability to photosynthesize at low
temperatures (40
degrees F), and ability to keep stomata open on relatively cold
windy days
during the summer. These studies have not been done for white
pine.
The red bark is an interesting phenomenon. White and black
spruce also
often have reddish bark as does bur oak at the northern edge of
the range.
I don't know why red bark would confer an advantage in cold
climates.
Lee
|
| RE:
White pine adaptability |
Will
Blozan |
| Feb
05, 2004 06:45 PST |
Lee,
I have noticed reddish bark on higher elevation eastern hemlock
in the
Smokies, too.
|
| RE:
White pine adaptability |
Robert
Leverett |
| Feb
05, 2004 08:03 PST |
Lee:
I remember Alan Gordon telling me once that studies of white
pine
showed that seed stock moved from one location to another where
the
change in latitude was over 2 degrees generally had major
adaptability
problems. I wonder if the 2 degree rule works for other species,
if it
is highly variable, and what might be the most adaptable species
in the
sense of taking seed stock from one location to another. Which
species
is the most latitudinally challenged?
Bob
|
| Re:
White pine adaptability |
greentreedoctor |
| Feb
05, 2004 08:21 PST |
| RE:
White pine adaptability |
Lee
E. Frelich |
| Feb
05, 2004 09:21 PST |
Bob:
It works that way (about 2 degrees latitude) for most species I
have seen
in the literature here and in Europe. It is
interesting, however, that if
you move trees to the other continent, they will grow well at
latitudes 5
or 10 degrees different than their origin, but only around 2
degrees on the
same continent.
Regarding red bark, Jacek Oleksyn (probably the leading expert
in the world
on tree adaptations to different latitudes), whose office is
next to mine,
says that trees in the northern part of their range have more
carotenoids,
which helps shield them from sunlight damage (especially UVB)
because of
longer days and lower sun angle in the north, and more intense
sun at
higher altitudes. He doesn't know if that causes redder bark,
but it is a
good guess.
Lee
|
| white
pine adaptability/northern range limit |
Neil |
| Feb
27, 2004 06:10 PST |
Hi Bob,
Finally clearing out my mailbox. Sorry this is not exactly
timely.
Lee's mention of reduced lignin in northern populations of
eastern white pine is interesting.
In the tree-ring world, maximum latewood density and annual wood
density is often tied to
summer temperatures through time is. As measured by x-ray
densiometry, wood density [and
latewood density] of trees at mountain and latitudinal treelines
fluctuates as temperature fluctuates.
Increased temperatures increase wood density [latewood density].
Researchers in Europe [Keith Briffa,
Fritz Scweingruber, etc.] and in the US [our lab, Laura Conkey,
etc.] have observed this relationship
in Japan, Alaska, Canada, NE US, Eurasia, etc.. They have found
this relationship in spruce and pine
[Pinus sylvestris], and, I think, larch. Hmm, it seems Malcolm
Cleaveland has done this work
with ponderosa pine and Douglas-fir, maybe other species, though
these studies are drought related.
Laura Conkey did her work in the early 1980s with red spruce.
Cold temperatures reduce ring density. These rings have
light-colored latewoods and lower density
following large volcanic eruptions. Tree-ring jargon calls these
rings light rings. The best example
I know of is the Laki Eruption and the low density of the 1783
ring in Alaska by Gordon Jacoby et al.:
http://www.earthinstitute.columbia.edu/news/aboutStory/about3_4a.html
Interestingly, core samples from treeline sites occasionally
break on the ring boundary [terminal
parenchyma] of these rings or frost rings.
We do not know much about eastern white pine because a
strong climate signal could not be derived from its rings so
this tree was "abandoned,"
dendrochronologically speaking.
So, wood density, especially latewood density, increases with
warm temperatures. It would be
neat to know if the same relationship holds across latitudes. If
so, it might help explain how Barry
Bonds et al. could swing a maple bat instead of white ash. I
think the maple comes from Canada.
Hope this helps,
Neil |
|
http://www.adobe.com/