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TOPIC: Tornados
http://groups.google.com/group/entstrees/browse_thread/thread/867e8095180bdc53?hl=en
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== 1 of 1 ==
Date: Sat, Jul 12 2008 6:41 am
From: Lee Frelich

ENTS:

The tornados and derechos of the last two days in MN have come very close
to several old growth forests remnants.

One of the videos on the Weather Channel last night and this morning from
near Wilmar MN, showed a tornado with the old-growth Rock Elm Forest that
we have talked about on this discussion from time to time in the foreground
(which hopefully implies that the forest itself was missed by the tornado).
About 6 tornados occurred yesterday between 4:00 and 9:00 pm and the Wilmar
video appeared on TV within an hour after the tornado.

The derecho accompanied by two tornados Thursday apparently hit Wood-Rill
and Wolsfeld Woods, two of the best old-growth maple, basswood and red oak
forests left in southern MN, with 300 year old sugar maples. I don't think
the winds were above 80 mph, so there was probably minimal damage. Maybe
some gaps were created that we can use in research. I will try to find out
what happened in the next few days. The same two forests were hit by the
mighty derecho of May 30 1998, which had much more powerful winds that took
a large branch off the state record green ash, which nevertheless retained
its record status. They were also given a close shave by the May 1967
tornado outbreak during which four F4 tornados smashed their way through
the Twin Cities Metro area.

There is still an area in Wood-Rill where all the older trees are crooked
from one of those 1967 tornadoes, and all the young ones that entered the
forest canopy afterwards are straight. When ever that mixture of tree forms
occurs you can date the tornado by either examining the eccentricity of the
ring patterns in the trees that were knocked crooked (the eccentricity
changes the year after the tornado as the tree starts to rebalance itself
by growing larger rings in the direction of the lean), or by the total age
or age from release of the younger trees (if they were suppressed seedlings
in the understory, their rings will suddenly get larger when the tree above
is removed by the wind; a new seedling that germinates after the storm will
have large rings from the pith because they were never overtopped by other
trees).

Lee

== 3 of 5 ==
Date: Mon, Jul 14 2008 3:28 pm
From: Lee Frelich


ENTS:

Today I found out that the old growth forests are OK. The world's only old
growth rock elm forest came very, very close to being wiped out by 150 mph
winds, but the tornado missed.

Lee
 

== 5 of 5 ==
Date: Mon, Jul 14 2008 6:35 pm
From: DON BERTOLETTE


Wow!
It's like summer snow in my neighborhood...living at the edge of a park/wildland that has cottonwoods in it, it has been 'snowing' cotton for several weeks now, with cotton collecting along pavement/grass interfaces, waterbodies, blowing light blizzards in windy days. You don't dare leave your car windows open outside, and screens are 'thickening'.
One of my first thoughts was one of Aldo Leopold's vignettes, where he wrote of the 'the land' and bemoaned those who would cut down nearby native cottonwoods because they would 'plug their screen doors' on hot spring/summer days...
-DonRB