Wetland Types of the Mid-Atlantic

2:00 p.m.

So while I am stuck ... might as throw out some intro to wetlands stuff -- just for reference/glossary purposes.

We will see if southern wetland habitats are markedly different ...


Bald Cypress Swamp: Cypress swamps -- dominated by the decidious conifer taxodium distichum -- can be found from Maryland south on poorly drained soils with lots of rotting stuff.  Water levels vary with rainfall and tides. In our area, visit the Battle Creek Cypress swamp in Calvert County -- this is close to the northern extreme of these wetlands.

Freshwater Tidal Marsh: Go the back of any creek in St Mary's County and you will encounter a freshwater tidal marsh. They are tidal because the incoming saltwater tide raises the water level and creates a dam, pushing the freshwater upstream causing the water level to change with the tide -- even though no salt water reaches the wetland! These wetlands are a blast to explore, assuming you don't mind getting wet and muddy. You will be rewarded with visits frm wood ducks, beaver and river otter. Well worth the adventure ...

Saltwater Tidal Wetlands: By far, the most common wetland type in St. Mary's County. These are the saltwater marshes doominated by spartina patens and spartina alterniflora. As the water levels can be highly variable they can be divided into areas of low marsh, high marsh and the upper edge which is only occasionally flooded by the highest of tides. These wetlands are important nursery grounds for birds, fish, crabs and snails and especially phytoplankton which wash into the Chesapeake in early spring, providing the food, the energy, for the season's renewal of life.

Mineral Flats: Mineral flats are low, wet areas that, in a previous, and one might imagine, more glorious, life were lakes or ponds. They can look like wet forests or pocosins though they are characterized by their saturated mineral soils with low organic matter content. As organics accumulate over time these wetlands may change to pocosins or wet forests.

Peat Bogs: Peat bogs are rare in St. Mary's County, though present and hidden. A peat bog is formed in non-draining soil where the accumulation of organic stuff is greater and faster than decomposition can get rid of it. Some peat bogs have been collecting dead plants since the last ice-age, almost 10,000 years ago! They are characterized by sphagnum and other mosses, acid water and may even contain rare carnivorous plants and the Atlantic White Cedar!

Pocosins: Also known as shrub swamps, a pocosin is a constantly wet, elevated but flat area dominated by shrub pines, though they are not always so shrubby -- there can also be tall pines as well! Pocosins are maintained by fires that can penetrate the peat and deter the growth of larger trees. This type of wetland can be found in the Great Dismal Swamp.

Spring Seeps: a seep is a place where small amounts of groundwater reach the surface and spread out across the surface. This creates a small wetland area that can be fed with water year round. Spring seeps are often periodic affairs, with high ground water levels seeping out with spring rains and winter snow melt.

Motel: Nansemond River

Vernal Pools: Vernal, or ephemeral, pools are not very common in teh mid-atlantic, but quite so in St. Mary's County. Vernal Pools are small rain or snow fed puddles that usually dry up by late summer. They provide valuable breeding habitat or amphibians and small invertebrates.

Atlantic White Cedar Swamps: This is the holy grail of mid-atantic wetlands! Very rare, occurring only along a 100 mile stretch of atlantic coastal plain, the Great Dismal Swamp was prime white cedar habitat. The atlantic white cedar is a picky tree, liking wet, organic rich, highly acidic wet soils. Like the eastern red cedar, its seedlings are fussy about getting started -- preferring lots of sunlight. So atlantic white cedar swamps start in open bogs, and considering how few bogs there are in the mid-atlantic, one can see how unique this wetland type can become.

Winter Wet Woods: What more can one say? They are wet forests in the winter, usually containing vernal pools and usually drying up by mid-summer when the rains have stopped and the snow melt has evaporated. The moisture in the soil and ground, for the short period it lasts, is very important for the development and movement of amphibians who are breeding in vernal pools.