Natural Resources
Conservation Service
Ecological site F147XY010PA
Coarse Mixed Floodplain
Last updated: 9/27/2024
Accessed: 11/24/2024
General information
Provisional. A provisional ecological site description has undergone quality control and quality assurance review. It contains a working state and transition model and enough information to identify the ecological site.
MLRA notes
Major Land Resource Area (MLRA): 147X–Northern Appalachian Ridges and Valleys
Major Land Resource Area 147 is in the Middle section of the Valley and Ridge Province of the Appalachian Highlands. Characteristic features include folded and faulted parallel ridges and valleys that are carved out of anticlines, synclines, and thrust blocks. The variability of weathering of the underlying bedrock has resulted in resistant sandstone and shale ridges separated by less resistant limestone and shale narrow to moderately broad valleys. The ridges are strongly sloping to extremely steep and have narrow, rolling crests, and the valleys are mainly level to strongly sloping. The Great Valley is a salient feature of the eastern portion and runs the entire length of the MLRA where it is called the Shenandoah Valley in the south. The western side of the MLRA is dominantly hilly to very steep and is rougher and much steeper than the rolling hills to the east. Parts of the northernmost section of the MLRA were subjected to pre-Illinoian glaciation (>770,000 years ago). Anthracite coal underlies some areas in the north and has been mined since the 1700’s.
Elevation in MLRA 147 generally ranges from 330 to 985 feet (100 to 300 meters) in the valleys and from 1,310 to 2,625 feet (400 to 800 meters) on the ridges and mountains. It is as high as 2,955 feet (900 meters) on some mountain crests and is nearly 4,430 feet (1,350 meters) on a few isolated, linear mountain ridges. Local relief in the valleys is about 15 to 165 feet (5 to 50 meters). The ridges rise about 660 feet (200 meters) above the adjoining valleys. (USDA, 2006).
Classification relationships
This ecological site is found in Major Land Resource Area 147- Northern Appalachian Ridges and Valleys, 148. MLRA 147 is located within Land Resource Region S - Northern Atlantic Slope Diversified Farming Region (USDA 2006), and in United States Forest Service ecoregion M221 – Central Appalachian Broadleaf Forest-Coniferous Forest-Meadow Province (Bailey, 1995). In addition, MLRA 147 falls within area #67 of EPA Ecoregion Level III – the Ridge and Valley (US EPA 2013). The Coarse Mixed Floodplain ecological site occurs primarily within 67b, and 67da of EPA Ecoregion IV - Northern Shale Valleys, and Northern Dissected Ridges and Knobs respectively (Woods et. al. 1996).
Ecological site concept
The Coarse Mixed Floodplain ecological sites are found on floodplains predominantly in small to medium stream and river valleys that drain the shale and sandstone uplands in MLRA 147, Northern Appalachian Ridges and Valleys. It occupies first bottoms of rivers and streams and natural levees. The soil and landscape characteristics are the result of high water velocity movement that favors the deposition of coarser, sandier and gravelly sediments relative to the silt loams, silty clay loams, and fine sandy loam textures of the Loamy Mixed Floodplain Ecological site. The underlying soil material formed in recent coarse alluvium derived from mixed sedimentary geology including sandstones, shales, siltstones, and limestone. They are well drained with moderate to rapid permeability. Soil textures range from sandy loams to coarse sands and gravels. These areas are subject to frequent flooding as classified by the National Soil Survey Handbook (USDA 2016). This is defined as more than a 50 percent chance of flooding in any year.
Much of this ecological site has been cleared for hay and pasture. Where forest exists, and flooding is frequent they are dominated by Betula nigra (River birch) and Platanus occidentalis (American sycamore) with associates including Acer negundo (Boxelder) and occasionally Acer saccharinum (Silver maple) and Fraxinus pennsylvanica (Green ash). In areas where flooding and ice-scouring is relatively more powerful, an early-successional woodland community may predominate that is characterized by stunted, usually battered and flood-trained trees of Platanus occidentalis and Betula nigra, with Salix species (willow) in the shrub layer.
Associated sites
| F147XY009PA |
Loamy Mixed Floodplain Loamy Mixed Floodplain |
|---|
Table 1. Dominant plant species
| Tree |
(1) Betula nigra |
|---|---|
| Shrub |
Not specified |
| Herbaceous |
(1) Impatiens capensis |
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