Roosevelt Island, Potomac Gorge   Darian Copiz   Dec 12, 2005 14:31 PST  ENTS, I plan on focusing my tree measuring efforts on two Washington D.C. areas. One of these is Rock Creek Park.   The other, which debuts in this report, is the Potomac Gorge. The Potomac River has several things which make it remarkable. Although the surrounding area is highly developed, the actual riverbanks and many streams feeding into it are not. Although people have long used the river, it has escaped the impacts of heavy industry and major dams. The biggest change to the river was the construction of the C&O Canal which stretches from Georgetown in Washington, D.C. to Cumberland, Maryland. This was started in the first half of the 19th century. The canal was closed in the 1920's. The canal and it's environs are now a national park that offer 160 miles of public access to the river and the bank along the Maryland side. There are many parks located on the Virginia side as well. The Potomac starts in the Allegheny Plateau, cuts through the Allegheny Front, the ridges and valleys, flows across the piedmont and enters the coastal plain at D.C. The section of the Potomac River known as the Potomac Gorge stretches from Roosevelt Island and Georgetown in D.C. to Great Falls 15 miles upriver in Montgomery County, Maryland. In this segment, the fall zone, the river has cut through metamorphic rock to form the gorge. The topography is most dramatic below the falls at Mather Gorge, where cliffs up to 60 feet high starkly line the swirling river. Because of the range of environments the Potomac traverses, its location at the meeting of various ecosystems, and the wide variety of habitats that are located within it, the gorge has a very high level of biodiversity including over 1400 species of plants within this small area. Dry floodplain terrace prairies are in close proximity to cool, moist, ravines. This is a river that has its hydrology roughly intact. It experiences floods, siltation, droughts, and ice flows. The Potomac Gorge is wild and scenic, and located only minutes from the heart of the nation's capital. There are many studies that have been done in this area and much more information is readily available on the web. I started measurements at Theodore Roosevelt Island (website for NPS:  http://www.nps.gov/this/) the mouth of the gorge. The island is a 90 acre elongated piece of land located directly across from the Kennedy Center and accessible from the George Washington Memorial Parkway in Virginia. The island has gone through several name changes starting as Analostan Island, later as Mason's Island, and the current name Theodore Roosevelt Island. No offense to Teddy Roosevelt, but personally I would prefer to have kept the original name which pays respect to the first historically recorded inhabitants. The property was in the Mason family (George Mason among them) from 1717 until 1833. It included well developed plantings and a plantation house. Interesting descriptions including comments on the vegetation on the island at the time can be found at this website: http://gunstonhall.org/landholdings/analostan_island.htm After the Mason's departure the site was used as picnic grounds. Union troops were stationed on the island in the Civil War and the house was also used as a hospital for smallpox patients. In the 1960's the island was purchased to create a memorial to Theodore Roosevelt. The constructed portion of the memorial, which is ringed by willow oaks, was dedicated in 1967. A sign along one of the paths states that most of the woods are less than 100 years old, with a few trees around that may be older. The island does not have major topographical change, however a significant portion of the island is upland woods that is underlain by mica schist. The fringes of the island are sedimentary soils although a few locations have bedrock outcrops. A swamp which transitions to marsh is located on the southeast side of the island. Most of the measurements are from the upland areas, a few are from the transition areas, and two or three are from the lowland or swampy areas. The upland is dominated by Quercus rubra. Liriodendron tulipifera is also common. Prunus serotina, Fagus grandifolia, and some other species of oak occur as well. Although Q. rubra was very common, oaks from the white oak group are noticeably very few. The lowland areas are primarily Acer saccharinum, Acer negundo, and Fraxinus pennsylvanica. Relative to other areas upriver along the Potomac, there are few sycamores. Interestingly, some of the largest trees occur near where the old plantation house used to be. It may be relevant that one of the early descriptions of the Mason plantation mentioned that the house was located in a grove of trees. In the immediate vicinity of the house site there are Juglans nigra which may be remnants from planted trees, and also what may have been J. regia (European walnut). Also fairly near the house site is a patch of fairly large Ailanthus trees. Although the island is almost entirely wooded in native tree species, the groundstory and shrub layer is very dense with invasive exotic species. Native shrubs that occur are spicebush and pawpaw. I saw several deer on the island - they might be hindering tree regeneration. An item of interest is that at the entrance of the pedestrian bridge to the island there is an oak which looks like it is probably a hybrid between a red oak and a willow oak. Tree measurements: Acer negundo - 10' 7" - 84.4' - another similarly girthed tree also occurs Acer saccharinum - 11' 6" - 103.0' Acer saccharinum - 15' 0" - 86.9' Carya cordiformis - 6' 10" - 103.4' Carya cordiformis - 12' 8" - 101.0' - double trunk, but minor trunk had fallen off Fagus grandifolia - 6' 8" - 74.5' Fraxinus pennsylvanica - 8' 9" - 101.5' - in upland area Ilex opaca - 2' 4" - 50.3' Juglans nigra - 10' 3" - 94.5' - not near old home site Liriodendron tulipifera - 9' 8" - 114.3' Liriodendron tulipifera - 10' 2" - 116.2' Platanus occidentalis - 8' 10" - 111.3' - in swampy area Prunus serotina - 9' 1" - 98.3' Quercus alba - 5' 4" - 76.8' Quercus coccinea - 6' 2" - 96.2' - nice red foliage still on tree Quercus rubra - 7' 4" - 100.4' Quercus rubra - 6' 9" - 108.1' Quercus rubra - 11' 5" - 117.5' - fairly near old home site Taxodium distichum - 7?' - 95.1' - in swampy area, probably planted Ulmus americana - 12' 9" - 98.4' Ulmus americana - 14' 9" - 96.5' - beautiful tree Rucker Index - 104.0' (using black walnut rather than bald cypress) I expect this to be one of the lowlier sites in the Potomac Gorge due to the exposure of the site and the relative youth of the trees. Darian   Home