Re: Trees northern range limit   lef
  Jan 31, 2004 16:21 PST 


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).

Re: Trees northern range limit
  Jan 31, 2004 18:26 PST 


   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?

Re: Trees northern range limit   lef
  Feb 01, 2004 15:19 PST 


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.


White pine adaptability   Robert Leverett
  Feb 04, 2004 13:08 PST 


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

Re: White pine adaptability   greentreedoctor
  Feb 05, 2004 03:34 PST 

Please find below some eastern white pine links of possible interest (patterns of adaptive genetic variations). Since the white pine is their provincial tree, Ontario has studied this subject much. Also, it turns out that the white pine once thrived in Colby's backyard.



Re: White pine adaptability   Lee E. Frelich
  Feb 05, 2004 06:29 PST 


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.

RE: White pine adaptability   Will Blozan
  Feb 05, 2004 06:45 PST 


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 


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?

Re: White pine adaptability   greentreedoctor
  Feb 05, 2004 08:21 PST 

I don't know if you had a chance to open this pdf or not. But it goes to the heart of your question.

Adobe Acrobat Reader (free) 

RE: White pine adaptability   Lee E. Frelich
  Feb 05, 2004 09:21 PST 


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.

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.:

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,