| Lower
MN River Valley cottonwoods |
Lee
E. Frelich |
| Nov
15, 2004 07:09 PST |
ENTS:
Yesterday I went on a hike with some friends in the lower MN
River Valley,
most of which (probably 20-25 miles) is in a variety of state
and federal
parks and refuges. The valley has semi-dwarf oak forest on sandy
soils or
on rock outcrops, and a mixture of prairie and oak groves above
the bluff
line. Below the bluff line is a mile wide floodplain with mixed
patches of
forest, marsh, shrub swamps and ponds. The forest is in patches
of
different ages that result from changes in the course of the
river over
time, as well as past human disturbance prior to acquisition for
public parks.
Within this age mosaic of lowland forest are small patches of
old growth a
few acres in size where the true giant cottonwoods live. I was
pleased to
pick up several new cottonwoods in the 15-20' cbh size class.
One tree we
saw from 200 feet away was likely about 22-24' cbh, but the ice
on the
swamp and pond between it and the trail is only 1 inch thick, so
we will
have to wait a while before we can walk over to it. These trees
have bark 4
inches thick, and have branches in the upper canopy 1-2 feet in
diameter
that change direction at 90 degree angles. These changes in
branch
direction result from a storm that broke off the rest of the
branch,
leaving a small side branch to become the main leader. These
giant trees
project well above the surrounding forest canopy, and have such
weird
canopy forms, that one can see them from a half mile away.
Lee |
|