Lockhinge Notes - Wetland types and Greymantle biomes
(Much of the text here copied from elsewhere! Use as reference only.)
→ Swamps are forested wetlands which are near large lakes and rivers. They have slow-moving waters and support woody plants, such as mangroves or cypress trees. Marshes on the other hand have the same water source but have softer, non-woody plants. Bogs are characterized by peats, left overs of dead plant material. Their water source is mainly from precipitation. The water in bogs has mostly a lower pH limiting survival of plants and animals as compared to marshes that have a neutral pH making them rich with plants and animals. Fens also have peat. They are high in nutrients and usually also pH neutral. → Swamps are forested, marshes are populated by herbaceous plants. Bogs accumulate peat. Fens have neutral or alkaline water chemistry. The types can overlap. Swamps - Generally have slow-moving water and reside adjacent to rivers or other moving bodies of water. The level of water in a swamp can vary considerably with the adjacent river.Marsh - Also a wetland that is adjacent to a moving body of water, but tends to not have much water movement. It also forms a transition between open bodies of water and dry land.
Bogs - These are wetlands that have a hard sealed clay soil bottom that prevents water from seeping out. Water collects in bogs (sometimes just from precipitation) and sticks around. These habitats are anoxic and dominated by sphagnum mosses and shrubs.
Fens - these are groundwater fed wetlands where a breach in a hard clay pan allows groundwater to seep up into the depression and form a wetland habitat.
Bog
They are characterized by spongy peat deposits, acidic waters and a floor covered by a thick carpet of sphagnum moss. Bogs receive all or most of their water from precipitation rather than from runoff, groundwater or streams. As a result, bogs are low in the nutrients needed for plant growth, a condition that is enhanced by acid forming peat mosses. There are two primary ways that a bog can develop: bogs can form as sphagnum moss grows over a lake or pond and slowly fills it (terrestrialization), or bogs can form as sphagnum moss blankets dry land and prevents water from leaving the surface (paludification). Over time, many feet of acidic peat deposits build up in bogs of either origin. They may have either considerable amounts of open water surrounded by floating vegetation or vegetation may have completely filled the lake. The unique and demanding physical and chemical characteristics of bogs result in the presence of plant and animal communities that demonstrate many special adaptations to low nutrient levels, waterlogged conditions, and acidic waters, such as carnivorous plants.
Fen
Peat-forming wetlands that receive nutrients from sources other than precipitation: usually from upslope sources through drainage from surrounding mineral soils and from groundwater movement. Fens differ from bogs because they are less acidic and have higher nutrient levels. Therefore, they are able to support a much more diverse plant and animal community. These systems are often covered by grasses, sedges, rushes and wildflowers. Some fens are characterized by parallel ridges of vegetation separated by less productive hollows. The ridges of these patterned fens form perpendicular to the downslope direction of water movement. Over time, peat may build up and separate the fen from its groundwater supply. When this happens, the fen receives fewer nutrients and may become a bog.
Marsh
Wetlands frequently or continually inundated with water, characterized by emergent soft-stemmed vegetation adapted to saturated soil conditions. There are many different kinds of marshes, ranging from the prairie potholes to the Everglades, coastal to inland, freshwater to saltwater. All types receive most of their water from surface water, and many marshes are also fed by groundwater. Nutrients are plentiful and the pH is usually neutral leading to an abundance of plant and animal life. Two primary categories: non-tidal and tidal.
Non-tidal Marsh
Mostly freshwater marshes, although some are brackish or alkaline. Frequently occur along streams in poorly drained depressions and in the shallow water along the boundaries of lakes, ponds and rivers. Water levels in these wetlands generally vary from a few inches to two or three feet, and some marshes, like prairie potholes, may periodically dry out completely. Highly organic, mineral rich soils of sand, silt, and clay underlie these wetlands, while lily pads, reeds and bulrushes provide excellent habitat for waterfowl and other small mammals. Due to their high levels of nutrients, freshwater marshes are one of the most productive ecosystems in the world. They can sustain a vast array of plant communities that in turn support a wide variety of wildlife within this vital wetland ecosystem. As a result, marshes sustain a diversity of life that is disproportionate with their size. In addition to their considerable habitat value, non-tidal marshes serve to mitigate flood damage and filter excess nutrients from surface runoff.
Vernal Pool
Formerly glaciated landscape (plains) is pockmarked with an immense number of potholes, which fill with snowmelt and rain in the spring. Some prairie pothole marshes are temporary, while others may be essentially permanent. Here a pattern of rough concentric circles develops. Submerged and floating aquatic plants take over the deeper water in the middle of the pothole while bulrushes and cattails grow closer to shore. Wet, sedgy marshes lie next to the upland. In smaller, more temporary pools, springtime wildflowers often bloom in brilliant circles of color that follow the receding shoreline of the pools. By early summer, the water has evaporated, and the clay pools appear brown, barren, and cracked.
Wet Meadow
Commonly occurs in poorly drained areas such as shallow lake basins, low-lying farmland, and the land between shallow marshes and upland areas. Some wet meadows are found high in the mountains on poorly drained soil. These wetlands, which often resemble grasslands, are typically drier than other marshes except during periods of seasonal high water. For most of the year wet meadows are without standing water, though the high water table allows the soil to remain saturated. A variety of water-loving grasses, sedges, rushes, and wetland wildflowers proliferate in the highly fertile soil of wet meadows.
Tidal Marsh
Some are freshwater marshes, others are brackish, and still others are saline, but they are all influenced by the motion of ocean tides. Tidal marshes are normally categorized into two distinct zones, the lower or intertidal marsh and the upper or high marsh. The lower marsh is normally covered and exposed daily by the tide. The high marsh is covered by water only sporadically. Saline marshes support a highly specialized set of life adapted for saline conditions.
Swamp
A swamp is any wetland dominated by woody plants. Swamps are characterized by saturated soils during the growing season and standing water during certain times of the year. The highly organic soils of swamps form a thick, black, nutrient-rich environment for the growth of water-tolerant trees. Swamps may be divided into two major classes, depending on the type of vegetation present: shrub swamps and forested swamps.
Swamp Forest
Often inundated with floodwater from nearby rivers and streams. Sometimes, they are covered by many feet of very slowly moving or standing water. In very dry years they may represent the only shallow water for miles and their presence is critical to the survival of wetland-dependent species.
Shrub Swamp
Similar to forested swamps except that shrubby vegetation predominates. In fact, forested and shrub swamps are often found adjacent to one another. The soil is often water logged for much of the year and covered at times by as much as a few feet of water because this type of swamp is found along slow moving streams and in floodplains. Mangrove swamps are a type of shrub swamp dominated by mangroves that covers vast expanses of land.
Other Wetlands
Estuary
Partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime environments and are an example of an ecotone. Estuaries are subject both to marine influences such as tides, waves, and the influx of saline water, and to fluvial influences such as flows of freshwater and sediment. The mixing of seawater and freshwater provides high levels of nutrients both in the water column and in sediment. There are many different kinds of estuaries.
Floodplain
An area of land adjacent to a river. Floodplains stretch from the banks of a river channel to the base of the enclosing valley, and experience flooding during periods of high discharge. The soils usually consist of clays, silts, sands, and gravels deposited during floods. Because of regular flooding, floodplains frequently have high soil-fertility since nutrients are deposited with the flood waters. This can encourage farming.