At 4:20 PM 4/1/96 -0800, Robert.R.Wise at net.bio.net wrote:
>Help,
>> I got another "stump-the-prof" question today in plant anatomy
>class. I told my class that growth rings in wood are due to episodic
>growth of the vascular cambium and its secondary xylem derivatives. The
>growth episodes are influenced by temperature (i.e. summer vs winter)
>and/or water availability (wet vs dry). A student pointed out that during
>the Midwest flood of 1993 many deciduous trees ceased growth and dropped
>all of their leaves and then resumed growth after the flood waters receded.
> He then asked if that event would cause a "growth ring". So now I'm
>asking you. What would you expect to see in the wood of a tree that had
>undergone a mid-season cessation of growth that was not due to a water
>deficit or cold temperatures?
Bob,
My prediction:
I think the tree probably made normal spring wood up until the
growth stopped and leaves abscised. I would guess the anaerobiosis
of soil would disrupt most root function and lack of leaves would
prevent any sugar supply to the stem to form new cells. I am
guessing perhaps a few cells of smaller diameter produced by the
cambium in the transition period. As the waters receded, normal
growth should be restored (or even some improvement as siltation
may have enriched the soil; of course erosion could have removed
much of the useful soil from around the roots). Again there may
be some transition back to normal cell size. This should create
an additional "growth ring" in that particular year. Now, who will
test that prediction?
ross
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