Tree Ring Growth
Why do bark and tree rings show greater growth on the north and
northeast sides of the tree?
I posed this question to an licensed arborist. Here is his response:
In general, this isn't true. Tree rings do show greater growth on certain
sides of leaning trees because the tree is trying to compensate (wind does
make trees lean) for the lean. There can also be additional growth on the
bottom of branches for the same reason.
As for prevailing winds: they would have to be very strong and continuous,
which is something usually found on a local or maybe regional scale. For
example, central Nevada is a windy, open and exposed place where 15+ mph
winds are common for the majority of the year. I think that trees could
show those winds in their rings (trees growing in central Nevada already
show a visible lean).
I have never heard of bark being thicker on one side over another, but
again, at a micro climate level, it could be feasible. But certainly not
common nor true for generalization.
They do not! Tree rings will vary in width depending on a large number of
environmental conditions from year to year and tree to tree. It would be
very rare to find uniform rings on any tree, but the variations can be
caused by competition from nearby trees, moisture, damage, fires, any number
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Update: June 2012