Hemlock Island, Allegheny River, PA  
  

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TOPIC: Hemlock Island, Allegheny River, PA
http://groups.google.com/group/entstrees/browse_thread/thread/743dc12b07d436e2?hl=en
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== 1 of 5 ==
Date: Thurs, Jul 17 2008 6:04 pm
From: "Edward Frank"


ENTS,

On Wednesday July 16, 2008 I met Dale Luthringer at 4:00 after work for a quick trip to Hemlock Island in the Allegheny River just north of West Hickory, PA. We had made several trips to the Allegheny River Islands in the past. In September 2007 Dale Luthringer, myself, and Anthony Kelley had visited a number of islands in the River between Buckaloons and Tionesta. http://www.nativetreesociety.org/fieldtrips/penna/ariw2007/ariw2007a.htm 

The goal of the trip was to explore and recon the remaining six of the seven islands that made up the Allegheny River Islands Wilderness area. The seventh island, Crull Island had been visited by Dale Luthringer previously. http://www.nativetreesociety.org/fieldtrips/penna/allegheny_islands.htm . In addition to those islands, we also stopped at several islands that belong to the US Forest Service but are not a part of the wilderness itself.



Courson Island from Tidioute Overlook

There also are a number of islands that are privately owned. One stretch of the river between Tidioute and West Hickory, a distance of 8 miles, was not canoed during the trip as it did not contain any of the islands that were part of the wilderness. It does, however, contain a number of islands owned by the US Forest Service and some private islands. The most prominent of these islands is Hemlock Island. The Western Pennsylvania Conservancy played a role in the preservation of a number of these islands. Over 25 separate land parcels on property abutting the river, totaling over 9500 acres, and 21 islands were purchased by the Western Pennsylvania Conservancy in the 1970s, 1980s, and 1990s with the objective of protecting the river's scenic beauty and wildlife habitat (Anonymous, 1988, 1992). The land was later turned over to the US Forest Service. Seven islands, totaling 368 acres, were designated a state wilderness in 1984 and a national wilderness area in the 1990s (US Forest Service, 1997). I am not sure if Hemlock Island is among their parcels, but their efforts should be commended in any case.



Hemlock Island

Dale had been past the island on canoe trips down the river years ago, but had not actually been on the island before. Last week we stopped up to check out the access to the island. It was hoped that the channel between the eastern river bank and the island would be shallow enough to wade, but the water was up and too murky to attempt. We scouted out some other islands, but did not adventure on to any of them on that trip. Using his mapping software, Dale reported the island was about 0.8 miles in length and 0.1 miles across, with an acreage of 42 acres. I would have guessed by comparison that the island would have been in the low 50's for acreage. From the riverbank we could see some emergent pines growing from the island.



Hemlock Pines

We had not encountered any white pines on any of the wilderness islands. The only white pine seen on the trip in Sept. 2007 was a single specimen growing on privately owned Fuelhart Island. From the boat we measured it to be approximately 115 feet. Looking at the air photos from www.terraserverusa.com A number of dark blotches could be seen on the upstream eastern side of the island that we believe represented evergreens on the island. Elsewhere on the perimeter of the island could be seen some larger deciduous trees- likely silver maples and sycamore tree.



Terraserver Segment

Looking at the structure of the island it consists of a series of s-shaped ridges originating as a sequential series of sand and gravel bars deposited by flood and ebb stages in the Allegheny River. As noted in previous reports Kinzua reservoir dammed the Allegheny upstream of this island in 1965 and has affected the overall dynamics of the river system. I am not sure of the specific age structure or geologic series of these bar deposits. In general the deposits at then upper end and tail end of the island are the youngest. The oldest deposits are likely the higher elevation deposits in the central and eastern side of the island.

We opted to take my small inflatable raft rather than one of the park canoes to the island because of the steep bank leading from the parking area down to the river. We arrived at the pull-off along the highway and gathered our gear, only to discover we were short some of our measuring equipment. Dale, being the measuring machine of the two of us was outfitted with a full set of gear, while I grabbed my camera, tape, ad rangefinder for a supporting role. We launched from a rock at the base of the steep bank, and realized we should have topped off the raft with more air before launching. It was not a matter of the raft sinking, but a little bit of water washing into the bottom as we set off. We soon landed on the far side and pulled the raft onshore. The bank rose for about 15 feet to a nice camping area ringed by pines and hemlock. We had not found hemlock on any of the islands we had previously visited. With that we were off and running measuring trees. Dale immediately started measuring the white pines and hemlocks. It was exciting to find species we had not documented previously.


Hemlock at Landing Area

After measuring a number of trees in the immediate area of the informal campsite we headed upstream/northward. The next area was a lower level terrace a few feet above the current river level. The are was heavily vegetated with masses of sensitive fern forming the floor of the forest and scattered sycamore, black locust, white ash, and hawthorn. We measured a few trees here and then we split up.


Fern Floor with Sycamore


Hawthorn

Dale continued to measure the pines, hemlocks, oaks, and hickories on the upper terrace, while I headed toward the northern end of the island. The northern end of the island was at the lower terrace level and became brushier with frequent patches of multiflora rose. The trees here were not that large, The biggest were a few sycamores in the seven to eight foot girth range and 70 to 80 feet tall. 


Sycamore Crown

There were also some silver maples in the same size range. One of the silver maples was a multitrunk specimen with perhaps ten separate stems each about a foot in diameter. These multitrunk specimens form as a result of damage to the original stem from flood debris and is a common occurrence with the species. In this setting I would say for trees of any size a multitrunk silver maple is more common than a single trunk specimen.


Multitrunk Silver Maple

The very top of the island was grassy and open covered with reed Canary Grass, an invasive grass to wetland areas. I rounded the top of the island and head back down the western side of the island. One tree worth noting was a large Black Willow that I did not measure. It was easily the fattest willow and likely the tallest found in the river islands complex. I would guess it was over ten feet in girth and 70 feet high at a minimum. Looking at the air photo of the island above a large channel with water can be seen cutting into the right (upstream) end of the island. Going down the west side (top of photo) along the finger formed by the channel I found several good sized silver maples.


Silver Maple 116 feet tall - rightmost trunk

The largest was 9 ft. 11 inches in girth, and measured 116 feet tall. It was located in a small patch of knotweed - one of the few significant patches found on the island. I crossed the channel on a fallen log and rejoined Dale. By this time Dale had measured several species of oak, maple, hickory, and many assorted species. I called him over to measure the large silver maple across the channel. We also measured basswood, and documented sassafras, flowering dogwood, Am. hornbeam, and cucumber tree in this immediate area.


Basswood along central swash

The northern, southern and western sides of the island represent bar deposits that are raised above the river level, but not to any great height, likely less than 10 feet on average. It is evidenced that these area flood periodically. The lowest tiers flood every spring, while the higher levels flood every few years. These areas are the same in character as was found on any of the other islands we visited. The eastern side was something completely different. This are was raised from 15 to 20 feet above the current river level. It looked as if it had not been flooded for an extremely long time.


Hemlock


Beech trees along the top of the bank

The trees were spaced and open as if they were a section of a forest typically found in a dry upland setting. The species diversity for the island was very high because species were found in this upland area that are not typically found in areas that are frequently flooded. We found 32 woody species on our less than four hour stay on the island, by far the highest of any island we have explored along the river. The only area at all similar was a short section of ridge along Thompson Island inhabited by some big red oaks.

The final prong of exploration of the day was a walk down a path toward the southern (downstream) end of the island. The upland forest setting gave way to a large open field of canary reed grass with a few scattered trees. We waded through the tall grass and measured a black walnut and a butternut poking their heads above the field.


Black Walnut amidst field of Reed Canary Grass

We had encountered this same character on other islands. In 1985 a series of tornados blew through the area, killing a number of people in the village of East Hickory and vicinity, and essentially denuding portions of several of these islands. I had noted on King Island an Baker Island that butternut was one of the few tree species growing among the fields of Reed Canary Grass. It appeared to me that these trees were present prior to the tornados and accompanying winds, and were broken off during the storms. They since have re-sprouted from stumps or roots that previously existed. The grass has prevented other species from re-establishing in these areas. The islands themselves as a whole can be best described as an open savannah setting dominated by sycamore and silver maple. There were patches of natural grasslands on the islands prior to any human alteration. These have for the most part been replaced by the Reed Canary Grass. Whitney (2001) described the general nature of the forest found on King Island, and that seems applicable to most areas Hemlock Island outside of the eastern upland:

http://naturetourism.allegheny.edu/essay_alleghenyriverislandswilderness.pdf  "The groundlayer is dominated by sensitive fern (Onoclea sensibilis). Ninebark (Physocarpus opulifolius), silky dogwood (Cornus ammomum), and buttonbush (Cephalanthus occidentalis) are common shrubs. Note the abundance of lianas (riverbank grape (Vitis riparia) and wild cucumber (Echinocystis lobata))...King's Island is fringed with canary reed grass (Phalaris arundinacea) and black willow (Salix nigra)" .

Reed Canary Grass in a nasty invasive species: http://en.wikipedia.org/wiki/Reed_canary_grass  Reed canary grass (Phalaris arundinacea) is a tall, perennial grass that commonly forms extensive single-species stands along the margins of lakes and streams and in wet open areas, with a wide distribution in Europe, Asia, northern Africa and North America...In many places, reed canary grass is an invasive species in wetlands, particularly in disturbed areas. When reed canary grass invades a wetland, it suppresses native vegetation and reduces diversity. The grass propagates by seed and rhizome, and once established, is difficult to eradicate.

http://www.inhs.uiuc.edu/chf/outreach/VMG/rcanarygr.html 

Across the field of Canary Grass were some other large looking trees. We waded through the grass to find some more sycamores, and silver maples of good, but not great size. Off toward the western side of the island I could see a large single stem silver maple. I pushed forward and Dale followed. Between us and the trees was a massive moat of multiflora rose bushes. Eventually we found, worked, pushed our way through being wounded in the process. Dale saw and measured the height if a slippery elm - the only one of the trip, but it was buried by brush ad briars to the point we could not get a girth. I would guess a diameter of around 2 feet. From here we pushed on to the large silver maple. This one was 14.7 feet in circumference and 102.1 feet high from underneath. We pushed through the multiflora roses to a more open area along the western side of the island. Working our way back toward our raft as it was getting dark we came across several large sycamores with girths greater than 10 feet and a couple other larger silver maples. Once we got back to our raft, we paddled across the river as it was getting dark, for a nice end of a good trip.

Statistics and Measurements for Hemlock Island:

Species                        CBH     Height  Comments

 

Am. Basswood             5.6        75

Am. Basswood             8.3        98.2

 

Am. Beech                    7.6        96

Am. Beech                    6.3        96.8

 

Am. Hornbeam              1.5        33.6

Am. Hornbeam              1.5        34.3

 

Apple                           4.7        N/A

 

Bitternut hickory            7.6        105.1+

Bitternut hickory            4.9        105.9

Bitternut hickory            5.4        108.1+

Bitternut hickory            5.5        108.1+

Bitternut hickory            7.3        111.6

 

Black birch                    5.5        78.1+

Black birch                    5.5        78.1+

Black birch                    6.4        96.1+

 

Black cherry                  6.8        87.1+

Black cherry                  5.2        95

Black cherry                  6.7        101

 

Black locust                  4.3        86.4

 

Black oak                     6.8        93.1+

Black oak                     7.1        115.5+

 

Black walnut                  3.3        50

 

Butternut                       N/A       29.4     Forgot to write the CBH down…

 

Cucumbertree                4          N/A

Cucumbertree                4.9        110.1

Cucumbertree                3.9        116.3

 

Dotted Hawthorn           1.3

 

E. hemlock                   5.3        53

E. hemlock                   4.5        58

E. hemlock                   7.8        104.4

 

E. white pine                 7.6        108.8

E. white pine                 9.2        110.2

E. white pine                 8.5        113

E. white pine                 10.3      113

E. white pine                 7.4        118.2    41 35.811N x 79 24.228W

E. white pine                 10(2x)   121.7

E. white pine                 8          123.1

E. white pine                 8.6        124.7

 

N. red oak                     10.6      81.1+

N. red oak                     10.8      96.1+

N. red oak                     N/A       106

N. red oak                     8.7        106.8+

N. red oak                     10.9      108

N. red oak                     7.9        109.2

N. red oak                     7.3        111.1+

N. red oak                     8.4        111.1+

N. red oak                     6.2        112.2+

N. red oak                     6.1        114

N. red oak                     7.4        114.1+

N. red oak                     9.2        116.4+

 

Pignut hickory               3.3        80.7

 

Red maple                    3          74.8

 

Sassafras                   3.1        48.4

Sassafras                   4.8        66.1+

 

Scarlet oak                   7.4        93.2+

 

Shagbark hickory          2.4        53.8

Shagbark hickory          5.7        107.1

 

Silver maple                  (3x)       95.4

Silver maple                  13.4      102.1+  41 35.620N x 79 24.475W

Silver maple                  14.7      102.1+  41 35.525N x 79 24.507W

Silver maple                  12.7(2x) 103.6

Silver maple                  9.9        116.4

 

Slippery elm                  N/A       95.9      multiflora rose barbwire 8 ft. up base

 

Sycamore                     10.5      115

Sycamore                     N/A       118.1

Sycamore                     7.8        121.1    41 35.836N x 79 24.212W

 

Vitus sp.                       1.8

 

White ash                      5.7        94.1      41 35.851N x 79 24.210W

White ash                      4.4        99.1+

White ash                      8.5        102.2

White ash                      8.7        114

 

White oak                     4.2        84.1+

 

Yellow birch                  2.7        76

 

 Species observed, but not measured =
         Black willow
         Flowering dogwood
        Mountain holly
         Sugar maple

 

Total Woody Species = 32 (most out of any Allegheny River Island surveyed to date)

 

Invasive species =
         Japanese barberry
         Reed Canary Grass      
         Japanese Knotweed
         Multiflora rose

 

Hemlock Island Rucker Index = 114.75

 

Species                        CBH     Height

 

E. white pine                 8.6        124.7

Sycamore                     7.8        121.1

N. red oak                     9.2        116.4+

Silver maple                  9.9        116.4

Cucumbertree                3.9        116.3

Black Oak                     7.1        115.5+

White ash                      8.7        114

Bitternut hickory            7.3        111.6

Shagbark hickory           5.7        107.1

E. hemlock                    7.8        104.4

 

This can be compared quite well to the Rucker Index for the Allegheny River Islands Wilderness as a whole from 2007 (including parts of Anders Run)

Allegheny River Islands Rucker Index = 114.27 (Oct.  2007)

Species                     CBH        Height                                       Site Comments

Sycamore                     12.1      145.5     Baker Island                 PA height record
Silver maple                  9.7        120.1     King Island                  NE height record, (Formerly 123.3')
White ash                     11.5      118.4      Anders Run N.A.
Swamp white oak         10.9      111         Anders Run N.A.         E. U.S. height record
Bitternut hickory           7.7        110.3      Baker Island
Black walnut                 7.7       110.3       Thompson Island
Shagbark hickory          5.5       109.6       Anders Run N.A.
Sugar maple                  8.7       108.1       Crull Island
Am. Basswood             9.8       105.1+    Thompson Island
Am. Basswood             7.8       105.1+    Thompson Island
N. red oak                    17.9(2x) 104.3     Buckaloons R.A.

There are several variants of Rucker Index that can be calculated. Merging the above list with the numbers from Hemlock Island and a new measurement of the Sycamore on Baker Island we have a Rucker Index of 119.2 for the Allegheny River Islands. It only drops to 118.6 if you eliminate Ander's Run entirely, replacing the White Ash from there with one from hemlock Island, and replacing the Swamp White Oak with the Sugar Maple from Crull Island. I have not seen these trees, so I don't know if that would be appropriate or not. The silver maple record on King is on a temporarily shore-attached peninsula, but clearly part of the island system overall.

Allegheny River Islands Rucker Height Index =119.2

Sycamore  147.7 Baker Island  PA height record
E. white pine 124.7 Hemlock Island
Silver maple  120.1 King Island  NE height record
White ash  118.4 Anders Run N.A.
N. red oak 116.4 Hemlock Island
Cucumbertree 116.3 Hemlock Island
Black oak 115.5 Hemlock Island
Bitternut hickory 111.6 Hemlock Island
Swamp White Oak 111 Anders Run N.A.
Black walnut  110.3 Thompson Island
119.2 Rucker Height Index

 

As noted above we identified a number of prominent invasive species on the trip: Japanese barberry, Japanese Knotweed, Multiflora Rose, and Reed Canary Grass. I am sure there are others, but they were not noted.

Many of the islands have evidence of Native American utilization. More recently the southern half of Crull Island was used for cattle grazing, there were a couple of gas wells on King Island. Thompson Island was the site of the only Revolutionary War battle in the region. http://naturetourism.allegheny.edu/essay_alleghenyriverislandswilderness.pdf  I am not sure how much the forests of Hemlock Island have been altered by human activities. Some of the trees I would estimate to being over 150 years old. A nice black cherry with balding found by Dale is one example. Many of the trees had evidence of wind damage in the past. The fattest basswoods and sassafras all had their tops blown off at some time in the past. I would guess winds related to the tornados of 1985.

The island certainly needs to be revisited and more time spent there that we were able to do in a single evening. There are several big sections of the island we did not see at all, let alone measure. I know there is a nice Black Willow to measure, and I believe we can get out species count higher, As a final note there were some fat grapevines on the island. The largest was a respectable 1.8 feet in girth.

Edward Frank (with Dale Luthringer)


== 4 of 5 ==
Date: Thurs, Jul 17 2008 7:20 pm
From: "Dale Luthringer"


Ed,

Thanks again for putting another one of our trip reports together. I'm
pretty close to putting out my latest trip to Ohiopyle State Park back
in April.

The Anders Run trees are located in the Allegheny River floodplain, not
on any islands. We could easily do a variation of RI's, one for the
Wilderness Islands, one for all the islands on the Allegheny River, then
another for the Allegheny River.

I bet we could get a select few black oak, black cherry, and white ash
to 150 years on this island, with a number of white pine, hemlock and
red oak in the 100-125 year range.

This island definitely needs another amphibious assault. I'll remember
to bring my clinometer this time.

Dale



== 2 of 5 ==
Date: Thurs, Jul 17 2008 6:38 pm
From: JamesRobertSmith


Sounds like a heck of a long day! Too bad about the invasive species.
Since there's a wilderness area there, wouldn't there be a project to
get rid of the invasive species?



== 3 of 5 ==
Date: Thurs, Jul 17 2008 6:50 pm
From: "Edward Frank"

James,

It was an evening trip, so a short day. There isn't any effort to remove the invasives, nor do I believe there is any funds to do so. The best thing to do would be to mimic the natural flood cycle by releasing large volumes of water from Kinzua Dam in the spring, but the flood zone has so many camps and properties that would now be flooded, by what would have been a normal flood prior to the dam, this is unlikely to happen. This would significantly cut back on the number of Multiflora Rose and the Japanese Barberry are not flood tolerant and would die back after a few floods. The Japanese Knotweed would be cut back dramatically with more frequent floods as well. It likely would not do much against the Reed Canary Grass. We can hope that they will re-initiate the flood cycles, but I would not hold my breath. (I have a problem with people building houses, businesses and the like in the flood plains - they are called flood plains because that is where the rivers flood - and then we use tax dollars to finance rebuilding in these same areas).

Edward Frank


== 5 of 5 ==
Date: Thurs, Jul 17 2008 9:28 pm
From: James Parton


Ed & Dale,

Outstanding report. You guys really got some measuring done.

Those inflatable boats are really useful. I have used them many times
to float rivers fishing. Using them to access areas of interest
concerning trees is an idea that has already occurred to me, like
visiting the Black River cypresses down near the Carolina coast. First
I gotta complete my move to a new home.

I have already found a forest of nice white pines near Lake Julian
that I intend to investigate. It is not far from my new home.

James P.