Philadelphia nature is all around us. Underneath the concrete and asphalt are natural landforms and habitats. The City of Philadelphia sits in a river valley. Philadelphia is a flat city except for the northwestern area. The city is flanked by two rivers, Delaware and the smaller Schuylkill.
The landforms in Philadelphia and the Delaware Valley are the Atlantic Coastal Plain and the Piedmont Upland (map of physiographic landforms of Pennsylvania).
The Atlantic Coastal Plain
This broad, flat sandy plain is where the bulk of the city of Philadelphia rests. Most of it only rises several feet above sea level. City Hall sits thirty feet above sea level. And some parts of Philly (namely in South Philly near the airport) are a few feet below sea level. The Atlantic Coastal Plain extends northward into Bucks County, along the Delaware River.
The Piedmont Upland
The Piedmont Upland province is a land of red, clayey, soils and gently rolling hills. The Northwest section of the City sits on this rolling hills. The neighborhoods of West Oak Lane, East Mt. Airy, West Mt. Airy, Chestnut Hill, Germantown, Manayunk, and Roxborough lie in this region. Parts of the surrounding Pennsylvania counties of Montgomery, Bucks, Chester and Delaware also sit in part or wholly in these upland hills.
Philadelphia’s dominant bio-region is the Eastern Deciduous Forest. Within this forest is the Oak-Hickory Forest, Northern Floodplain Forest (Northern Riverine) and Freshwater Tidal Marshes.
Eastern Deciduous Forest
This forest of hardwood deciduous trees covers the eastern half of the North American Continent. The area is naturally covered with forests broken by open grassy fields, marshes, and rivers. The trees are softwood evergreens in the north, deciduous trees in the middle and tropical trees and evergreens in the south. Different groups of trees characterize different habitats. A good book to learn about the ecology of this forest is A Field Guide to Eastern Forests: North America (Peterson Field Guide).
The Oak-Hickory Forest
The main trees of this forest are oaks and hickories which drop their leaves in autumn. It is a nut-producing forest and is abundant with Blue Jays, Squirrels, Chipmunks, Turkeys, and other nut-eaters. In the Wissahickon Forest of Philadelphia, the dominant trees are White Oak, Red Oak, Black Oak, Chestnut Oak, and Tulip Tree.
The Northern Floodplain Forest
This forest borders rivers and waterways. The trees in this forest can survive the periodic flooding from the water level due to heavy rains and runoff. It is a habitat not sharply defined from a drier upland forest and can be spotted by the species growing alongside the water. The trees of this forest include Red Maples, eastern Sycamore, Shagbark Hickory, River Birch, and Sweet Gum.
Freshwater Tidal Marsh
This community consists of soft-bodied emergent plants which grow partially in and partly out of the water. In Philadelphia, the best site to see this is Tinicum (John Heinz National Wildlife Refuge) in South Philly. Here the tides from the Delaware River (and human-made) systems cause the water levels to rise and fall.