Canoeing to Crull and Thompson Islands, ARIW, PA

April 02, 2009. I went canoeing for the second time in a week. The goal of both trips was to visit the two uppermost islands of the Allegheny River Island Wilderness in northern PA. This is the countries smallest national wilderness. The first island is Crull Island, 96 acres in size. The second is Thompson Island, 72 acres in size. Portions of each island had been farmed in the past, but still they contained some extremely large trees in what could be characterized as an old growth forest. A week ago Carl Harting, myself, and Dale Luthringer put our canoes in a Brokenstraw Creek for a short trip to the Allegheny River itself. Dale had to schedule the trip a month in advance, and as luck would have it, it was the worst day in weeks that found us on the river. It was a light cold rain as we paddled down the river.

We put in at the top of Crull Island. The very top of the island had been flooded recently.  Debris had been swept from the surface leaving a muddy flat interspersed by some channels and pools.  Underlying the mud is a layer of harder coble sized rocks deposited when the island was affected by the full flow of the river, prior to the construction of the Kinzua dam a short distance upstream.  The edges of these islands would be washed away and the redeposited in the same area as the spring floods rose and fell.  The change of the flood regime will affect the long term stability of the islands that have persisted for likely several thousand years.  It already is affecting the flora growing on the islands. 

 

Upper end of Crull Island

One of the goals of this trip was to remeasure some large hackberry trees first documented by Dale in 2004.  The tallest he found at that time was measured at 99 feet tall, and we wanted to get a new measurement to see if we could find a sprig over 100 feet.  Also on the earlier trip Dale had not been able to explore the entire island, parts of the downstream end still needed to be explored. 

 

Carl Harting with Hackberry

We started to measure some magnificent trees.  There were American Sycamores measured to a heights of over 130 feet.  Carl Harting found an exceptional white ash (Fraxinus Americana) at 131 feet tall, by far the tallest found on any of the islands.  We measured a variety of other species. I was impressed by the jungle like quality of some hawthorn thickets on the island.  While Dale and Carl hunted big trees I measured some of the miscellaneous species found scattered about the island.  I measured a couple nice hawthorn trees – the tallest was 38.9 feet. 

 

Field of reed canary grass, Crull Island

In the central portion of the island was a large open area that in the summer would have been a field of reed canary grass.  I am not sure if this was a natural open area or what had once been a farm field now overgrown by this invasive.  In the midst of this field of canary grass are patches of hawthorn and hawthorn is encroaching on the open area.  There is a dearth of other species present in these open areas dominated by canary grass.  They are filling in around the edges behind the hawthorn.  Hawthorn seems to be the only pioneering species that is capable of overgrowing the reed canary grass.

Dale Luthringer with thick grapevine

I added butternut, staghorn sumac, and some others.  In the midst of an impressive patch of hawthorns and a couple apple trees there were fat grape vines.  One measured 1’ 3” in girth.  I managed to measure a nicely formed black cherry, 8’ 9” in girth and 75 feet tall with a thick fork about ten feet up.  Another interesting tree was a white ash 11’ 2” in girth and 96+ feet tall.  The tree forked a dozen feet off the ground to make two equal size trunks.  Between the two forks the lower trunk split all the way to the ground.  Looking in the crack it appeared that the tree was a single trunk with the break splitting the base vertically and not a double trunk tree.    

White Pines on downstream side of Crull Island

Near the far end of the island we found a pair of white pines. In our explorations of all the other islands of the wilderness area, these were the first white pines we found anywhere. It was on the higher downstream end of the island above most of the flood waters. While canoeing past Fuelhart Island, a privately owned island in the river located among the islands of the wilderness itself, a couple years ago we did see one white pine, but did not stop on the private property to measure it.  We also found some white pine on another privately owned high island – Hemlock Island farther downstream. By this time, after a brief let-up in the rain, it was raining harder than ever. We could not use our instruments in the rain. It was miserable, so we abandoned the rest of the trip and paddled downstream to out take-out point across from Thompson Island. Again as bad luck would have it, Carl and I swamped are canoe just as we reached shore at the pullout – an appropriate ending for a rainy day.

Crull Island landing

The second trip on April 2 went much better. It was just Dale and I this time. Carl unfortunately could not make it.  Frost was on my windshield as I left in the morning. We again out in at Brokenstraw Creek and paddled down the river, this time in the morning sunlight. The first stop was again Crull Island  There were a couple of loose ends we needed to finish, ad we also needed to explore the downstream tip of the island.  On the first trip I had photographed a nice musclewood (Carpinus caroliniana) but had not measured it.  The first order of business for me was to relocate that tree.  Once found we looked for the tall white ash Carl had found on the previous trip.  I wanted to take some photos and to confirm the height of it and some of the tall sycamores.  Rain can play tricks on the rangefinder.  We found the trees and confirmed their heights. 

Looking at the hawthorn trees in the reed canary grass field, there were two distinct forms I could see.  If the branches had not been still bare, likely they would have been indistinguishable.  I pointed this out to Dale, and after a bit he also decided these might represent two different species of the tree.  At the Johnstown Flood Museum National memorial the bio-inventory report lists six different species of hawthorn growing in old fields.  I don’t know who did the identification and how reliable they are, but it is a curios tidbit that seems to fit here.

 

Sycamore, 15.8 foot girth, 76.7 feet tall

The going downstream along the left edge of the island we explored some new territory we had not managed to visit on the first trip because of rain.  This area was generally open with reed canary grass.  Silver maples grew along the river bank.   The tallest topped out at 110.8 feet. One fat silver maple one had a girth of 15.8 feet, but was only 76.7 feet tall.  Once we reached the point Dale and I split up to explore a bit more.  I started measuring hawthorns in a thicket along the right bank.  They were tall for the species, but I could not break 40 feet.  Then pay dirt!  I found a 44.4 foot tall hawthorn.  From here I swung back up the island to where the pair of white pines were located.  Absent the rain I was able to get a better height of 94.8 feet for the taller of the two trees.  Then it was back to the canoe.  I had hoped to find a yellow birch sighted on the first trip in the pouring rain, but somehow missed it.  We had only found one other on Baker Island in our explorations of the wilderness islands. There were many waterfowl on and around the island, and three white-tail deer scooted across the island as we explored.

From Crull Island we headed down to Thompson Island. An immature bald eagle flew ahead of us as we paddled. We had explored the upper portion of the island previously, but the lower third was impassible due to a thick mass of Japanese knotweed, a nasty invasive species, up to ten feet tall that formed a dense thicket. After the winter the knotweed had died back and we could see into the area and force our way through it. We managed to measure a number of big sycamores and silver maples in the midst of what had been the knotweed thicket.  Of particular note was a tall silver maple we measured at 128.9 feet. This makes it the tallest of its species known in the Northeastern US.

   

Silver maple champion, 128.9 feet tall, girth 10 feet

I also was able to photograph a massive seven trunk silver maple at the lowest end of the island. We found it on a previous trip, but the photos did not turn out well. The tree had a combined girth of 24 feet and was 108 feet tall. 

 

Multi-trunk silver maple

At the lower end of the island we found what appeared to be a manmade channel cut into the edge of the island.  A cut square timber could be seen in the bottom of the water course.  Perhaps this was a grist mill, or a sawmill at some time in the past. 

 

Alleopathy under a small hawthorn

We documented more tree species on this trip that we had not measured before, including river birch and black willow. The last things of note were the hawthorns.  Again we had two distinct forms of the tree here on Thompson Island.  Underneath one of the smaller trees in the midst of the canary grass was a darker patch of grass, smaller in size.  The thick mats of downed canary grass were absent.  This could be an example of chemical alleopathy on the part of the hawthorns and could explain why they have been able to colonize into the reed canary grass while other species have not.  The afternoon was sunny and reached into the low 60’s. About 5 pm we headed across to the pullout. We were both a little sunburned and tired by now, but it had been beautiful day on the river.  The only thing missing was Carl on this second trip

Moss Cypress

On the way back from Thompson Island we stopped at Buckaloons and measured the Moss Cypress growing there.

 Ed Frank

 

Data Compilation  by Dale Luthringer