Turkey Run Park is an area I have frequently visited. In November 2010, Will and I measured a few trees there. I had been meaning to go back to thoroughly measure the area, but had been planning to work my way up the Potomac Gorge, out of D.C., so it had not been first on my list of places to measure. However, with the arrival of emerald ash borer in the region it got bumped in priority. Will mentioned an ash over 130 feet in his report, and I had also noticed some impressive ashes while hiking through the area at various times. This winter was likely my last opportunity to measure ashes in the park, as next year will probably be too late. Unfortunately, in the meantime other areas will not have their ashes documented.
Turkey Run Park is a small area north of George Washington Memorial Parkway between Turkey Run and the next stream to the east. Jurisdictionally, it is part of the Parkway and also houses the headquarters for the Parkway. Technically, the area that Will and I had previously measured was actually outside of Turkey Run Park, but still within George Washington Memorial Parkway land. Much of the area I measured over this winter was also outside of the technical Turkey Run Park, but mostly within the Parkway land. Some of it was south of the parkway and included much of Langley Oaks Park. The map below depicts the areas I measured outlined in green. The area outlined in yellow, was a valley with particularly tall trees. Of interest, the tan area to the lower right of the map, is the CIA.
Historically, much of the area had been farmland. However, the steep slopes along the Potomac may have been wooded for many years. A map from the 1860s depicts many of these slopes as being forested, but also shows a soapstone quarry in one location within the park. The remains of the quarry are still apparent. There are additional signs of disturbance and development along the river, but overall it is less disturbed than other portions of the Potomac Gorge, especially compared to areas lower down the river. Some of the trees are clearly quite old. I counted 174 rings on the stump of a white oak near the park entrance. The stump was 9 feet in circumference at 1 foot above the ground. I’m sure other nearby trees are older.
As Will mentioned in his report, the slopes along the Potomac consist of rich woods. These slopes can be categorized as basic mesic forest – a forest type which is not common in the vicinity other than along the Potomac. This forest type, combined with the other variety of habitats, and the fairly large area measured resulted in a high diversity of species. Silver maple was not very well represented even though it is very common and attains large sizes elsewhere in the Potomac Gorge. I would have also expected ironwood and river birch to attain larger sizes. On the other hand, there were very good specimens of quite a few other species. I spent 14 days between December and March, measuring a total of 232 recorded trees, representing 42 species.
As previously mentioned, the area outlined in yellow on the map was especially rich in tall trees. It contained the tallest tulip, red hickory, red oak, and beech, and one of the tallest black walnuts. Just outside of the area were also the tallest mockernut hickory and scarlet oak.
The Flora of North America and the Integrated Taxonomic Information System don’t recognize Carya ovalis as a separate species. I tend toward being more of a lumper myself, but included C. ovalis here in order to distinguish between differences I noted in the field, and because the Flora of Virginia recognizes it as a species. The nuts were used for identification, with the red hickory shells clearly splitting to the base, often with small ridges along the edges of the segments. Interestingly, I did not find the bark of these trees to be any shaggier than trees with C. glabra type nuts, and actually often found C. glabra to have shaggier bark. Another interesting difference is that I found three C. ovalis trees over 145 feet tall, but the C. glabra type didn’t get over 139’. Will had measured a pignut as 138.7.’ I believe the tallest one I measured was the same tree, but I ended up slightly shorter at 138.3’ – I may have missed the top, or it hasn’t gotten taller.
Another tree Will measured has grown. The basswood he measured as 124.5’ I measured to 128.5.’ Tilia is not very common in the region, but along the Potomac at this location it is fairly abundant. Almost all of these trees are curved and form a long arc. However, the tallest one is very straight, with no sign of the trunk curving. Some of the less straight ones were still tall though. I measured three others over 120 feet tall.
I tried, but unfortunately wasn’t able to match Will’s 150.0’ for sycamore, but only achieved 148.5. I also didn’t match the pawpaw measurement and fell short of the bitternut hickory measurement by 0.1.’
I believe the site has a mix of sugar and black maple. I primarily used fallen leaves for identification. The leaf shape is the primary characteristic the Flora of Virginia uses to distinguish. This wasn’t always very clear though, and I wasn’t always certain of the identification.
In regards to ashes, the area did not disappoint. It will be sad to see them all die though, which is already underway. Green ash is the predominant species and achieved impressive height. Some large girthed trees were also included. I’m doubtful if the species gets much taller in the Potomac Gorge, so I’m glad I got to this site before they are gone.
The forest around Turkey Run is some of the nicest in the area and is also known for its spring display of wildflowers. Despite the constant hum of the parkway, frequent planes, and occasional helicopters it can feel fairly wild at times, especially when one is down by the Potomac and the hills and river flow block the sound of traffic. Wildlife I saw over the winter included deer, fox, turkey, bald eagles, hawks, a black snake (in hawk’s talons), and a variety of other birds as well as signs of beaver. It is fortunate to have this area of rich natural heritage so close to the city.