FULL LECTURE NOTES ON WETLANDS

3 types of wetlands




Wetlands are the land area that is saturated with water, either permanently or seasonally, such that it takes on the characteristics of a distinct ecosystem.

wetlands are generally distinguished from other water bodies or landforms based on their water level and on the type of plants that strive within them.

specifically, wetlands are characterized as having water table that stands at or near the land surface for long period each year enough to support aquatic plants.

wetlands vary widely due to local and regional difference in topography, hydrology, vegetation and other factors including human activities

Example of the world largest wetland includes Pantanal in Brazil,Bolvia, and Paraguay in South America etc.




wetland hydrology

wetland hydrology is associated with spatial and temporal dispersion, flow, and physicochemical attributes of surface and ground water in reservoir

based on hydrology wetlands can be categorized as;

  • riverine (associated with streams)
  • lacustrine (associated with lakes and reservoir)
  • palustrine (isolated)

sources of hydrological flows into wetlands are predominantly precipitation, surface water and groundwater

water flows out of wetlands by evapotranspiration, surface runoff, and subsurface water outflow




characteristics of wetlands

  • the water table (the groundwater level) is very near to the soil surface or shallow water covers the surface for at least the part of the year
  • soils: wet or hydric soils develop recognizable characteristics after being saturated for several weeks. a mixture of brown and grey mottles near the surface usually means the water table fluctuates during the year and may support wetland vegetation. dark grey soils are usually very wet or hydric
  • vegetation: wetland plants, called hydrophytes, are the most obvious indicator that one is standing in the wetland area. numerous field manuals are available to help identify wetlands plants




Wetlands can be grouped into the following categories:

Bogs and fens

a bog is a freshwater wetland usually formed in the old glacial lake with a spongy peat base. other characteristics of bog include growth of evergreen trees and shrubs and the floor covered by thick carpet of sphagnum moss

Most of the bog water comes from rain. they are usually found in glaciated areas of northern united states of America

one type of bog, called a pocosin, is found only in the southeastern coastal plain




A fen is a freshwater peat wetland covered mostly by grasses, sedges, and reeds of high PH (alkaline) groundwater. fens are covered by grasses, sedges, reeds and wildflowers. fens like bogs, tend to occur in glaciated areas of the northern united states of America and other parts of the northern pole areas

The soil in bogs is low in nutrients.

Marshes

these are areas with shallow water that are mostly grasslands.

Marshes can be freshwater or saltwater and the amount of water in the marshes can also change without tides.

Freshwater marshes have soft-stemmed and herbaceous plants like grasses, shrubs, and wildflowers.

Marshes are home to animals including beavers, alligators, and newt. Marshes have soil that is low in mineral content.




They can be found along edges of lakes, rivers, and along the coastline, inlets and estuaries. 

marshes can be categorized as tidal marshes and non tidal marshes

tidal (coastal) marshes

these occur along costlines and are influenced by tides and often by freshwater from run off, rivers or ground water.

salt marshes are the most prevalent types of tidal marshes and are characterized by salt-tolerant plants such as smooth cord, grass, and grassworts

according to the salinity of the flooding water, freshwater, brackish and saline tidal marshes are distinguished




tidal marshes can be categorized into coastal marshes and estuarine marshes

non-tidal (inland) marshes

are marshes dominated by herbaceous plants and frequently occur in poorly drained depressions, floodplains and shallow water areas along the edges of lakes and rivers

major regions of the united states of America that support inland marshes include the great lakes coastal marshes, the prairies pothole region, and Florida everglades




Swamps

these are slow-moving streams, rivers, or isolated low-lying areas with more open and deeper water than marshes.

in other words, swamp Is a shallow body of water in a low-lying area, which is poorly drained. They usually have a variety of tree species such as cypress. Swamps act as a sponge because runoff can be temporarily stored in them

Plants found in the swamps include trees such as cypress trees in freshwater swamps and mangroves in saltwater swamps.

Swamps have more woody shrubs than grasses and herbs. Swamps are found in low-lying areas near rivers or coastal areas. Swamps soil is poorly drained and waterlogged.




A swamp is any wetland dominated by woody plants.    There are many different kinds of swamps, ranging from the forested Red Maple, (Acer rubrum), swamps of the Northeast, to the extensive bottomland hardwood forests found along the sluggish rivers of the Southeast

swamps are characterized by

  • saturated soils during growing seasons
  • standing water during certain times of the year

some swamps are dominated by shrubs, such as button bush or smooth alders.

plants birds, fish, and invertebrates such as freshwater shrimps, crayfish, and clams require the habitats provided by swamps

many swamps occur along large rivers, where they are critically dependent upon natural water level fluctuations




types of swamps

forested swamps

these are found in broad floodplains and receive flood waters from nearby rivers and streams

common deciduous trees found in these areas include bald cypress, water tupelo, swamp white oak and red maple

shrub swamps

these are also called scrub swamps or buttonbush swamps they are type of freshwater wetland ecosystem.

they occur in areas too wet to become hardwood swamps (forested swamps) but too dry or too shallow to become marshes

shrub swamps are similar to forested swamps except that shrubs by species like buttonbush and swamp rose dominate




mangrove

this refers to a habitat comprised of a number of halophytic (salt-tolerant) plant species of which there are more than 12 families and 50 species worldwide.

mangrove grows in intertidal or estuarine areas

importance of swamps

  • swamps help to maintain water quality by removing and retaining nutrients and processing chemical and organic wastes such as urban pollutants and agricultural chemicals
  • filter pollution
  • prevent erosion and flooding
  • habitat for animals
  • provide food
  • recreation
  • research and education




importance OR advantages of wetlands

  • Wetlands prevent flooding by holding water much like a sponge. By doing so wetlands help to keep rivers levels normal and filter and purify surface water. in other words wetland can temporarily store rainwater and thus slow down and spread out the timing of runoff. this helps protect downstream areas from flooding and erosion
  • Wetlands release vegetative matter into the river, which help feed fish into the rivers.
  • Many coastal and inland wetlands are popular location for tourist and recreational activities such as swimming, boating, fishing, camping and bird watching.
  • Wetlands are highly productive ecosystem that provide the world with nearly two third of its fish harvest.
  • Many animals that live in the other habitat use wetlands for migration and reproduction. For example herons nest in large trees but need shallow areas in order to wade for fish and aquatic life. Amphibians also often forage in uplands areas but return to the water to mate and reproduce
  • Erosion control, emergent plants (plants firmly rooted in muddy bottom bot with stalks above water surface) are able to radically slow the flow of water. As the result they  can counter the erosive forces of moving water along lakes or rivers and in rolling agricultural landscapes
  • Wetlands clean the water by filtering out sediments, decomposing vegetative matter and converting chemicals into useful forms.
  • It support agricultural activities by providing water for irrigation and livestock and for domestic consumption. Pasture on inland floodplain wetland are more productive than those in adjacent areas.
  • wetland areas are source of water supply. wetland are reliable source of water and if the underlying geology is suitable, are major source of ground water resupply
  • fisheries: wetland provide spawning and nursery ground for many species of fish
  • food chain : food materials produced in wetlands support fish and wildlife in adjacent areas




  • education and scientific research: wetland provide outdoor laboratories and living classroom for studying and appreciating natural history, ecology and biology
  • open spaces and aesthetic recreation: wetlands provide variety in the landscape and relief from development. they provide a sense of connection to the natural world

problems facing wetlands areas

  • Industrial activities, this threat comes from draining wetlands for establishing industrial sites also industrial  activities are threats to wetlands because of dumping of industrial wastes to wetlands.
  • Tourism, many tourist activities taking place in wetlands have lead to draining of these wetlands so as to establish tourist facilities like hotels or camping sites.
  • Agricultural activities, these are big threats to wetland since farmers drain and farm in wetland due to its fertility and availability if water. Hundreds of thousands of hectares of wetlands have been drained for agriculture.
  • Pollution, this is growing concern in wetland areas, affecting drinking water sources and biological diversity. Drainage and run off from fertilized crops and pesticides used in agriculture introduce nitrogen and phosphorous nutrients and other toxins like mercury to water sources. These chemicals can affect the health and reproduction of species posing a serious threats to biological diversity.




  • Climatic change, increase in temperature are causing polar ice to melt and sea level to rise. This in turn  is leading into shallow wetlands being submerged and some species of mangrove trees being submerged and drowned. Yet at the same time other wetlands such as estuaries, flood plain and marshes are being destroyed through drought.
  • Dams, worldwide there ere now over 40000 dams which alter the natural flow of water and impact on existing ecosystem.
  • Introduction, illegally or otherwise of non traditional or alien species into wetlands such as water hyacinths, Nile perch and clay fish
  • Over exploitation of wetland resources, increasing human population and change from subsistence to commercial exploitation  of wetlands resources continue to exert pressure on limited wetland resources resulting into its decline.
  • Establishment of new settlement in wetland areas




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