Natural Resources
Conservation Service
Ecological site F145XY001MA
Silty High Floodplain
Accessed: 05/07/2024
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): 145X–Connecticut Valley
The nearly level floor of the Connecticut River Valley makes up most of the area. Nearly level to sloping lowlands are at the outer edges of the river valley. These lowlands are broken by isolated, north- to south-trending trap-rock ridges that are hilly and steep. Elevation ranges from sea level to 330 feet in the lowlands and from 650 to 1,000 feet on ridges.
Recent alluvium has been deposited on the nearly level flood plain along the Connecticut River since the glacial retreat about 10,000 to 12,000 years ago. These deposits created some of the most productive agricultural soils in New England. Glacial lake deposits, outwash, and recent alluvial deposits dominate.
The area primarily supports central hardwoods. Habitat loss and fragmentation are widespread throughout the lower part of the Connecticut River Valley. The major tree species in the rest of the forested areas are sugar maple, birch,beech, oaks, and hickory. White pine and hemlock are the dominant conifers, but pitch pine and red pine are more common on sandy soils. Red maple grows on the wetter sites.
The most common understory plants are moosewood and hobblebush in the northern part of the area and dogwood in the southern part. Abandoned agricultural land is dominated by white pine and paper birch in the northern part and red cedar and gray birch in the southern part. The important upland habitats include trap-rock ridges and sand plains. Oak woodlands and cedar glades are common on the ridges. Black oak savannas mixed with pitch pine and varying amounts of little bluestem are common on the sand plains. Other habitats of significance include wetlands associated with the Connecticut River freshwater marshes, swamps, flood plains, and lowlands. The dominant trees on the flood plains are black willow, cottonwood, and sycamore.
Classification relationships
USDA NRCS:
LRR: Northeastern Forage and Forest Region
MLRA 145 Connecticut Valley
USDA USFS:
Province221: Eastern Broadleaf Forest
Section 221A: Lower New England
Subsection 221Af: Lower Connecticut River Valley
EPA Ecoregions:
Level III: 59 Northeast Coastal Zone
Level IV: 59a Connecticut Valley
Ecological site concept
The site consists of deep, coarse-silty, well drained, alluvial soils on high floodplains of mostly large river valleys but can occasionally be found within small river valleys. The site is flooded less frequently or for a shorter duration than low floodplains. Representative soil is Hadley.
The reference community is a sugar maple – basswood forest. Associated plants include white ash, bitternut hickory, black walnut, ostrich fern, waterleaf, wild ginger, and presence of other rich herbs. Unlike low floodplain forests, silver maple is absent from this community. Limited examples of this forest type exist since they have mostly been converted to agricultural use. River types such as large, low gradient and small-medium low and high gradient rivers differ in hydrologic regime and fluvial geomorphology and consequently have different community composition (Marks et al. 2011).
Associated sites
F144AY006CT |
High Floodplain Levee The High Floodplain Levee site occurs on excessively drained soils along rivers. |
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F145XY002MA |
Silty Low Floodplain Low Floodplain occurs on moderately well drained soils. |
Table 1. Dominant plant species
Tree |
(1) Acer saccharum |
---|---|
Shrub |
(1) Staphylea trifolia |
Herbaceous |
(1) Matteuccia struthiopteris |
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