We woke up early the next morning and made our way past Anders Run
Natural Area, down river to Thompson Island. It was so foggy we
couldn’t see across the river. It was so foggy when we got down to the
put-in point, that I couldn’t tell whether we even had the right island
or not. Thankfully, I took GPS readings a couple of years ago when I
measured some decent sycamore from the road that were on the island’s
edge.

We were across the river in no time and pulled the canoe up the bank.
It just so happened to be near the base of an Am. basswood, which was
the largest I had ever personally measured, at 11.3ft CBH x 94.4ft high.
We then started to pick our way through the multiflora rose barbwire
undergrowth on our way towards the center of the island, looking for a
new PA sycamore and new NE US hackberry height records. I had earlier
measured a sycamore to 135.3ft a couple of years earlier, but had never
been able to set foot on this island. It appeared there were slightly
taller ones in the center, and we were not disappointed.

very old Slippery Elm

 Hawthorn Tree

We reached the center of the island and starting working our way
up-river and into a nice riverine sycamore forest where we were quickly
getting into numerous sycamore in the upper 120 to low 130ft height
class. Ed was first to strike pay dirt when he found a new state height
record for sycamore at 10.6ft CBH x 140ft high. There were a number of
other nice sycamore in the area, but we weren’t able to find another to
top it… on Thompson Island, that is…

 Japanese Knotweed jungle covering the southern halfof the island

We did our best to break into the snotweed jungle, but were thwarted at
every attempt. We attempted an ‘end run’ which led us to a couple of
old high water stream bed channels that cut 6-10ft deep swaths into the
sediment through the snotweed forest. There were nice N. red oaks on
the rivers edge, but we couldn’t get far into the interior of the
snotweed. We did manage to chop a short swath in on the edge of one of
the old streambed channels, to the base of a very nice sycamore that
went to 14ft CBH x 122.1ft high… just a taste of what possibly lay in
the interior.

Ed found a channel that worked our way out the bottom end of the island,
where we bushwhacked back up-river to the canoe, while estimating
sycamore & silver maple heights from the rivers edge into the knotweed
jungle. Most sycamore on the bottom end of the island would go to the
upper 120ft class, with some going just over 130ft. It is very possible
there were taller ones in the bottom center of Thompson Island, but this
will have to wait for a spring trip after the snow and ice had given a
proper beating to the snotweed.

Then for fun, I decided to canoe AROUND the island to make sure we
didn’t miss anything on the fringe. Turns out it wasn’t that much fun
on the upstream paddle. It was a hot day and I only brought one canteen
of water (Bob, the sorriest man in the outfit is the first one to
water!). Ed was going through Mountain Dew like it was going out of
style… I do commend him for the effort. Any lesser man would’ve
committed mutiny after we had gotten half-way upstream the backside of
the island. The Allegheny River is no small river. It easily has 3
times the flow of the Clarion River during its low flow stages, and we
were paddling up small rapids most of the way. Thompson Island is one
of the longest islands on the Allegheny River that tops out at just over
1 mile long and 228 yards at its widest point. This doesn’t count
another ¼ mile long island just upstream that is part of Thompson Island
during low flow. A small diagonal side channel, which was 75% dry when
we portaged through it, separates a small island just upstream from the
main Thompson Island. Needless to say, there were no more ‘1 canteen
days’ for the remainder of the expedition. Two quarts was the bare
minimum per day.

Common understory trees were small white ash, slippery elm, bitternut
hickory, and ironwood. Black locust, black walnut, Am. Basswood, and N.
red oak were dominant on the fringe, but sycamore was clearly the canopy
dominant species when present. Other species that were present but not
measured where choke cherry and shagbark hickory. Thompson Island’s
stats follows:

9/3/07

Thompson Island

Species                        CBH     Height   Comments


Am. Basswood              11.3      94.4      personal largest measure

Am. Basswood              7.8        105.1+
Am. Basswood              9.8        105.1+
Am. Hornbeam              2.5        35.6
Am. Hornbeam              1.2        35.7
Bitternut hickory            5.6        N/A
Bitternut hickory            4.6        96.1+
Bitternut hickory            6.8        104.4
Black cherry                  4.3        88.9
Black locust                  7.2        90.1+
Black walnut                  7.7        107.6
Black walnut                  7.7        110.3
Black willow                  9.9        84.5
Common hackberry        7.2        81.1+
Common hackberry        7.2        83.3
Hawthorne sp.               4.7        N/A
Hawthorne sp.               3.4(2x) 3 3
Hawthorne sp.               3.1        34.4
Hawthorne sp.               5          34.9      107 AF Points
N. red oak                     10.5      N/A
N. red oak                     10.4      78.1+
N. red oak                     13.1      90.1
N. red oak                     13.4      100.4+ 12x100 class
N. red oak                     13.5      102+     12x100 class
Pignut hickory                4.3        90.9
Red maple                     8.8        86.8
Silver maple                   11.3      90.1
Silver maple                   11.2      99.1+
Silver maple                   20.7(5x) 102.1+
Silver maple                   12.7      103.9    12x100 class
Silver maple                   24(7x)   108+
Silver maple                   10.2      110.5
Slippery elm                  11.2      87.1+    “old growth” tree
Sugar maple                   7.8        N/A
Sycamore                      14         122.1    beauty, in knotweed
forest
Sycamore                      N/A       127.6
Sycamore                      9          132.3+
Sycamore                      7.5        134
Sycamore                      6.6        134.1
Sycamore                      9.1        135.1
Sycamore                      7.3        135.5
Sycamore                      8.4        136.8+
Sycamore                      10.6      140       new PA height record, if only for a day…

Vitus sp.                       1.4
Vitus sp.                       1.6        
White ash                     8.2        93.1+
White ash                     9.3        98.5
White ash                     7.3        111.1+


Species present but not measured = choke cherry, shagbark hickory,
staghorn sumac

Invasives = Japanese knotweed, multiflora rose

Thompson Island Rucker Index = 105.34

Species            CBH     Height

Sycamore           10.6      140
White ash           7.3        111.1+
Silver maple       10.2      110.5
Black walnut       7.6        110.3
Am. Basswood    9.8        105.1+
Bitternut hickory  6.8       104.4
N. red oak           13.5      102.1+
Pignut hickory      4.3        90.9
Black locust        7.2         90.1+
Black cherry       4.3        88.9

Dale

P.S. future river sections to follow