What exactly is a wetland, and why are they so important?
A wetland is a piece of land covered with water, at least part of the time. They are not lakes or oceans, but shallow ponds or stretches of land where water saturates the ground. Wetlands cover around 6 percent of the earth’s land mass. Nearly one third of all plant species live in wetlands.
When construction projects cause the destruction of a wetland, by law a comparable wetland must be created elsewhere to replace it.
Wetlands act like enormous sponges, soaking up water and drawing it down into aquifers while filtering out soil and waste. They also protect homes and communities against floods by soaking up heavy rainfall. More than half of the world’s population depends on rice, which grows in flooded paddies, and around two-thirds of all the fish we eat spend part of their lives there. Herring, salmon, lobster and shrimp are born and raised in wetlands.
Wetlands teem with wildlife. Birds that nest there include red-winged blackbirds, swamp sparrows, great blue herons and ducks and geese. Otters and minks hunt for fish and crayfish, and turtles, frogs and water snakes are often seen. Many species of dragonflies and butterflies can be found here, too.
There are different types of wetlands, classified according to the plants that grow there, soil pH and water levels.
A marsh is a wetland in which reeds, sedges and bulrushes are the dominant plant species. Marshes provide excellent habitats where birds that migrate can rest and find food. Two local examples are Conneaut Marsh in Crawford County and Independence Marsh in Beaver County.
Fens have a water table below the surface of the soil. They are still wetland habitats and the soils are always moist to the touch. Unique plants grow in fens’ alkaline soil, including fringed gentians (Gentianopsis crinata) and grass-of-Parnassus (Parnassia glauca). They can be found in Lawrence County Fen. Lowville Fen in Erie County features the native orchid, yellow lady’s tresses (Spiranthes ochroleuca). Both sites are owned by the Western Pennsylvania Conservancy.
A bog is a wetland in which the water supply is entirely from rainfall. The soil is acidic and poor in nutrients and oxygen. Few plants are adapted to survive in bogs. Sphagnum, comprised of moss and other dead plant material, is found in bogs. It can absorb and hold up to 15 times its weight in water and stay persistently moist without rainfall. Plants such as cranberries and blueberries grow well in bogs. Their tough, woody stems filter water and utilize the few nutrients available. Clammy azalea (Rhododendron viscosum), pitcher plant (Sarracenia spp.), sundew (Drosera spp.) and golden club (Orontium aquaticum) also tolerate the acidic environment.
Bog habitats are rare and have been acquired by conservancies and private groups hoping to preserve them. Titus Bog in Erie County is owned by the Botanical Society of Western Pennsylvania, which leads limited trips to the bog. Sulphur Springs and Toplovich bogs are in Warren County. They are owned by the Northern Allegheny Conservation Association.
A swamp is a wetland where shrubs and trees are the dominant plant species. Buzzard Swamp in Marionville and Black Swamp in Butler County are two local examples. Common swamp plants include buttonbush (Cephalanthus occidentalis), swamp rose (Rosa palustris) and willow (Salix spp.). Many wildflowers grow along the swamp’s dry edges.
Wetlands are special ecosystems and are the perfect place to enjoy nature. Their diversity of plant and animal species provide ample subjects for photographers. Schollard’s Wetlands in state-owned game lands near Volant has raised, flat trails perfect to explore.
Dianne Machesney is a Penn State Master Gardener. This volunteer program supports the outreach mission of Penn State Extension and provides research-based information on best practices in sustainable horticulture and environmental stewardship. Information: alleghenymg@psu.edu or 412-482-3476.
First Published: December 1, 2017, 1:00 p.m.
