2 points to contribute here...
I think we've debated this one before Bill, where I argued that old/mature
trees that survive topping probably do so 'despite' the treatment, not
because of it.
But that's the point isn't it? Some do survive despite severe crown
reduction. A suggestion that all will succomb is not in fact true. So this
points to developing an understanding of what tree characteristics or work
considerations (timing, %redeuction/year, etc.) will allow survival. And
remember to distinguish physiological from structural survival. If the
choice
is "fell it to be safe" or "top it and see if it makes it" maybe some
individuals do survive because of the reduction.
And the brief period which we administer trees is commonly a
fairly short period relative to their lifetime. So their vulnerability to a
premature demise, as a consequence of such work might not be so apparent
Sorry if I repeat here... the same consideration applies to drilling for
decay
mapping. I started out suggesting that there may well be times when VTA is
insufficient for decision making and a "decay map" is desirable. I would
hope
tomographic methods become reliable enough to offer an alternative to
drilling. I have little issue with drilling some roadside tree where safety
is
the principal concern. I have great issue if we are dealing with
some "veteran" of great cultural significance. If drilling reduces its
lifespan by 100 years three of us will have retired and it's likely the third
will not recall what the first did, but IMO it's not acceptable... well not
desirable anyway... to deprive three generations of that cultural assest.
--
Scott Cullen
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