Section 221B--Hudson Valley

Geomorphology. The Section is the northernmost extension of the Ridge and Valley geomorphic province. It is characterized by a linear lowland, a glacial lake plain in part, bounded on either side by high escarpments. The lowland was created by graben-faulting, easily eroded bedrock, and glacial scour. Fluvial erosion, transport and deposition, and mass wasting are the primary geomorphic processes operating. Minimum elevations range from about 200 ft (61 m) in the north to near sea level south of Long Island Sound. Maximum local elevations are generally less than 500 ft (152 m) but range to 1,000 ft (305 m). Gentle slopes cover 50 to 80 percent of the area, 50 to 75 percent occurs in uplands.

Lithology and Stratigraphy. Pleistocene lacustrine sediments cover the northern half of the central lowland; the remainder is covered by Quaternary alluvium. The uplands have thin, stony till over bedrock. Ordovician carbonate, shale, siltstone, and sandstone form bedrock in the lowlands. Uplands to the east are Ordovician-Cambrian metasediments and metavolcanics; to the west are Silurian conglomerates and Devonian lime stones.

Soil Taxa. Dystrochrepts and Fragiochrepts with udic moisture regime and mesic temperature regime are most common in the lower Hudson River valley and along the margin of the Catskill and Taconic Mountains. Hapludalfs with mesic temperature regime and udic moisture regime are more commmon in the upper valley.

Potential Natural Vegetation. Küchler vegetation types include northern hardwood and Appalachian oak forest. Regionally defined important vegetation types include central hardwoods, transition hardwoods, and northern hardwoods grading from south to north. Albany sand plains support pitch pine-scrub oak communities.

Fauna. With European settlement, the original forest ecosystems and their forest-dependent fauna were reduced to marginal areas. With the re-establishment of forest on abandoned agricultural lands, many forest wildlife species have returned to their pre-settlement distributions and numbers. Large predators have not re-established themselves, either naturally or by re-introductions; and the reduced predation on major herbivores, especially white-tailed deer, has resulted in an increasingly widespread problem. Acorns are an important resource of forest habitats, providing an energy source that drives many wildlife processes. Fragmentation of forest cover by residential development is an important concern. Excessive deer populations are a major wildlife problem. Deer damage domestic plants and agricultural crops, destroy natural forest regeneration, and cause motor-vehicle accidents. Common wildlife species include white-tailed deer, gray squirrel, white-footed mouse, red-eyed virio, and red-spotted newt. No Federally listed threatened and endangered species are unique to this area.

Climate. Average annual precipitation is 40 in (1,020 mm). Average annual snowfall is from 40 to 60 in (1,020 to 1,520 mm). Average annual temperature ranges from 45 to 50 ºF (7 to 10 ºC). The growing season lasts for 160 to 180 days.

Surface Water Characteristics. The Hudson River and its tributaries dominate the unit. Perennial streams, small lakes, and fresh water and saltwater wetlands occur. The Hudson River is a low gradient incised stream. Major tributaries from the Taconics and Allegheny plateau have moderate and steep gradients. Under natural conditions, daily saltwater tides in the Hudson River would reach as far upstream as Albany, New York. Average annual runoff ranges from 10 to 22 in (250 to 560 mm). March and April are the months of highest streamflow. Lowest streamflow occurs in August.

Disturbance Regimes. This region generally lacks large-scale natural disturbance regimes; however, fire is an important small-scale disturbance in the maintenance of pitch pine-scrub oak communities on sand plains and ridges along the middle to lower Hudson River Valley. In general, forestland occurs on edaphic extremes, i.e., steep, shallow, or otherwise unsuitable land for farming or settlement. All forestland is in second or third growth. Insect and disease disturbances have resulted from chestnut blight, Dutch elm disease, beech bark disease, butternut canker, and ongoing wooly adelgid infestation.

Land Use. Roughly 60 percent of this area is in forest, but with minimal forestland adjacent to the river and its urbanized corridor. The remaining land area is in urban, residential, and agricultural use.

Cultural Ecology. Native American occupation and ecological exploitation began as early as 10,000 years ago. These early inhabitants evolved from mobile, nomadic hunting groups to more sedentary groups, adapting to subsistence-based farming and hunting. European exploration began in the 1600's. The fur trade was a prominent activity in the area during the latter 17th and early 18th centuries. Settlement of towns and cities increased in the 19th century in response to the growing shipping industries along the Hudson River and banks of Lake Champlain. Today, a vast number of industries provide employment for the area's dense population.

Compiled by Northeastern Forest Experiment Station, Northeastern Area State and Private Forestry, and the Eastern Region.