Ecolog:
Quite! Thank you Jane, for putting it in better (and more neutral) words
than I.
I have a photograph of a hazardous tree as an example, but don't know how to
send it to all Ecologgers efficiently. If someone knows how to post it where
everybody can see it, I'll send it to them. I'll send one or two to Jane,
and she can feel free to share it if she wishes.
I've inserted a few comments into Jane's text [[thus]].
WT
----- Original Message -----
From: "Jane Shevtsov" <jane....@gmail.com>
To: <ECOLOG-L@LISTSERV.UMD.EDU>
Sent: Sunday, January 20, 2013 5:05 PM
Subject: Re: [ECOLOG-L] Tree stump removal in sensitive area
The number of people killed by falling trees each year isn't really the
information we need. That number could be low because few decayed trees
kill (or severely injure) people or because there are few such trees in
populated areas.
What we really want to know is the probability that a decayed tree will
fall on somebody (or come close) when it eventually falls, given that it is
in an area frequented by people. We can guesstimate this by finding out
what fraction of the time there are people in the tree's fall zone [[some
fraction of 360 degrees? WT]], adjusting for any inaccessible
areas/directions. (Yes, this ignores things
like weather, but that's what makes it a back-of-the envelope estimate.)
Suppose there are no inaccessible areas around the tree and there are
people near it about 1/4 of the time. Then the probability of a hit or near
miss when the tree eventually falls is 1/4 -- quite substantial in my eyes.
Adjusting for weather and time of day or treefall may reduce it to 5% or
10%, which is not small considering the stakes. [[There are lots of factors
to be considered in tree hazard potential assessment, but this is an
excellent start. The task is to decide which tree is definitely hazardous
and which trees are not obviously hazardous, and back-of-the-envelope WAGs
and SWAGs will do for starters. The objective of tree hazard assessment is
to get the "low-hanging fruit" (yuk, yuk!) or top priorities first, then
work on the more marginally-hazardous ones next, and so on . . . WT]]
Some might object to this calculation, saying that it could be used to
justify the removal of any urban trees. But the chances of a randomly
chosen urban tree falling in the near future are very small and we can
generally detect the conditions [[Yes, but sometimes the reasons are so
well-hidden that no one could have detected the defect. I used to do
"post-mortems" on urban trees, and one that looked "normal" turned out to
have been planted years in the past (by a famous horticulturist) in a
"rootbound" condition--a major root had wound around the other main
structural or "tap" root at the bole and in effect "squeezed" it (prevented
its lateral expansion) to the point that it could no longer support the tree
and it broke off more than a foot below the soil surface. WT]] that make a
tree likely to fall. The
estimate above only makes sense for a tree that we know is likely to fall
in the near future. If you wanted to, you could multiply the probability by
an estimate of the probability of the tree falling in the next ten years
(or whatever the time horizon of interest is), which the calculation above
assumes to be 100%. [[Some trees are obviously going to fall sooner rather
than later; for example when there is excessive lean, or when stress cracks
appear in the soil. No one can know when the tree will fall because we have
no present means of which I am aware that can measure the stress on roots
without increasing the failure potential. But if tree managers were allowed
to follow a kind of triage system where those considered most likely to fall
were preemptively removed, the number of falling trees, and thus the total
hazard, could be reduced, not eliminated. WT]]
Jane Shevtsov
On Sun, Jan 20, 2013 at 12:32 PM, Nirmalya Chatterjee
<buba...@gmail.com>wrote:
Sorry to contradict you here Wayne, but your argument is anecdotal and
seems to be as straw-manly as GWPatton's - people who work in the Forest
Service are likely to get injured by trees, (lethally or otherwise) from
falling branches, trees etc. - there's a term for that - occupational
hazard. That doesn't necessarily mean that the general populace has the
same odds of facing such an injury.
2010 CDC data indicate 4.88% accidental deaths (at #5 reason), and ~80% of
those were due to poisoning, accidental falling and motor vehicle related,
that pushes other reasons to sub-1% levels. Wind related tree failures
caused 31 deaths/year from 1995-2007.
http://www.bama.ua.edu/~jcsenkbeil/gy4570/schmidlin%20tree%20fatalities.pdf
.
That's 407 people in 12 years, don't blame the trees here. Blame human
carelessness, thoughtlessness and Nature's unmitigated fury (the last
cannot be controlled). Trees would be the means here, not the cause. My
point being, yes there are some activities which cause people to be
injured
- but this always begs the question of what the odds are. As for the
irrational fear of urban people to dying from tree-related as related by
GWPatton - in my anecdotal experience, yes such fears exist. And trees are
easy to pin the blame on, they aren't vocal about it, and with urban areas
heavily paved and a whole gamut of underground disturbances related to
utility lines etc., it is expected trees don't really find the unfettered
access to the soil to stabilize themselves as evolution and Nature
intended. The solution lies in learning to think more holistically instead
of knee-jerk reactions, which many tend to do.
And talking to "victims" of tree-fall injuries or their family members to
get your ideas about its dangers is not proper science, neither is hearing
anecdotes from of the likes of you, both would be called biased sources. I
am yet to hear families and victims of auto accidents stopping riding or
driving cars (in significant numbers), post-accident. Or people stopping
use of household poisons because some one they knew mistakenly drank rat
poison. As scientists it behooves us to keep emotion out of science.
NC
On 19 January 2013 23:11, Wayne Tyson <landr...@cox.net> wrote:
> Ecolog:
>
> I know I won't convince "Me" that while public safety concerns about
> falling trees (and dropping branches) might sometimes be exaggerated,
> the
> truth is that trees do fall and break and people die from it, and it is
> only prudent to get the dangerous ones down before they fall down.
"Me's"
> point is also irrational, on this basis, and using straw-man arguments
does
> not advance the issue, it only adds an emotional component. He knows
damned
> well I did not imply that every tree that falls is going to kill
> someone;
> thankfully, even in heavily-used areas such deaths are somewhat rare,
> but
> that does not mean that dangerous trees should not be removed. Talk to
the
> families of the victims and tell them you stopped the tree that killed
> their loved one from being removed. In my area, a public protest
prevented
> a severely leaning large tree that showed clear signs of root failure
> opposite the direction of the lean from being removed. Those people
should
> have to face the families of the victims, but "God" will be blamed, as
> usual. What poppycock!
>
> WT
>
> PS: I have lost one friend to a falling tree, almost another, and
> several
> people have been killed over the years in my community by falling trees
and
> branches. While running a tree survey strip when I was in the Forest
> Service, I was narrowly missed by a big widowmaker, and I saw a logger's
> body being carried out with his flattened hard hat where his head used
> to
> be. A widowmaker. That's how frequently falling branches kill people in
the
> forest--there's even been a name for them for years.
>
> ----- Original Message ----- From: "Me" <gwpatt...@yahoo.com>
> To: "Wayne Tyson" <landr...@cox.net>
> Cc: <ECOLOG-L@LISTSERV.UMD.EDU>
> Sent: Saturday, January 19, 2013 8:20 PM
> Subject: Re: [ECOLOG-L] Tree stump removal in sensitive area
>
>
>
> Omg. The moment it falls, someone is in the perfect position to be
fatally
> injured. That's the reason there is a war on trees in the Washington DC
> area. There is this unreasonable perception that something that looms
over
> us is out to kill us. Parks here have trees near paths cut for the same
> irrational fear. Yet you can go to other states like NY or ME and find
> that there is no such rampant tree culling. There is a distorted
perception
> of risk to me versus averaged risk to populations.
>
> Geoff Patton
> Wheaton, MD
>
> Sent from my iPhone
>
> On Jan 19, 2013, at 12:23 PM, Wayne Tyson <landr...@cox.net> wrote:
>
> Good idea in the wild, but in a place where there are lots of people,
one
>> has to think of what it hits when it falls after the roots rot
enough--it's
>> just fine until that instant when the last bit of rot or burrowing
rodent
>> or whatever cuts the last bit of dead tissue--and BAM! Somebody's dead.
>> Drawing birds and other creatures into the urban context is wonderful,
but
>> I worry about the populations of predators like domestic and feral cats
and
>> the lack of understory for laddering fledglings up off the ground when
they
>> make their first hard landing. Context is everything.
>>
>> WT
>>
>> ----- Original Message ----- From: "eann" <e...@gsinet.net>
>> To: <ECOLOG-L@LISTSERV.UMD.EDU>
>> Sent: Saturday, January 19, 2013 7:02 AM
>> Subject: [ECOLOG-L] Tree stump removal in sensitive area
>>
>>
>> Rather than worry about stump removal, why not cut the tree off higher
up
>>> and leave it for cavity birds?
>>>
>>> Ann
>>> ~*~ ~*~ ~*~ ~*~ ~*~ ~*~ ~*~
>>> E. Ann Poole, NH-CWS
>>> Poole Ecological Consultancy
>>> PO Box 890, 741 Beard Rd
>>> Hillsborough, NH 03244
>>> (603)478-1178
>>> e...@gsinet.net
>>> www.eannpoole.com
>>> ~*~ ~*~ ~*~ ~*~ ~*~ ~*~ ~*~
>>>
>>>
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>>
>
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--
-------------
Jane Shevtsov, Ph.D.
Mathematical Biology Curriculum Writer, UCLA
co-founder, www.worldbeyondborders.org
“Those who say it cannot be done should not interfere with those who are
doing it.” --attributed to Robert Heinlein, George Bernard Shaw and others
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Checked by AVG - www.avg.com
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