Sources of hydrological flows into wetlands are predominately precipitation, surface water, and ground water. Water flows out of wetlands by evapotranspiration, surface runoff, and sub-surface water outflow.
Hydrodynamics the movement of water through and from a wetland affects hydroperiods temporal fluctuations in water levels by controlling the water balance and water storage within a wetland. Landscape characteristics control wetland hydrology and hydrochemistry. The O 2 and CO 2 concentrations of water depend on temperature and atmospheric pressure.
Hydrochemistry within wetlands is determined by the pH, salinity, nutrients, conductivity, soil composition, hardness, and the sources of water. Water chemistry of wetlands varies across landscapes and climatic regions.
Wetlands are generally minerotrophic with the exception of bogs. Bogs receive their water from the atmosphere and therefore their water has low mineral ionic composition because ground water has a higher concentration of dissolved nutrients and minerals in comparison to precipitation. The water chemistry of fens ranges from low pH and low minerals to alkaline with high accumulation of calcium and magnesium because they acquire their water from precipitation as well as ground water.
Salinity has a strong influence on wetland water chemistry, particularly in wetlands along the coast. Carbon is the major nutrient cycled within wetlands. Most nutrients, such as sulfur, phosphorus, carbon, and nitrogen are found within the soil of wetlands. Anaerobic and aerobic respiration in the soil influences the nutrient cycling of carbon, hydrogen, oxygen, and nitrogen, [21] and the solubility of phosphorus [22] thus contributing to the chemical variations in its water.
Wetlands with low pH and saline conductivity may reflect the presence of acid sulfates [23] and wetlands with average salinity levels can be heavily influenced by calcium or magnesium.
Biogeochemical processes in wetlands are determined by soils with low redox potential. The biota of a wetland system includes its vegetation zones and structure as well as animal populations. The most important factor affecting the biota is the duration of flooding. In fens, species are highly dependent on water chemistry.
The chemistry of water flowing into wetlands depends on the source of water and the geological material in which it flows through [25] as well as the nutrients discharged from organic matter in the soils and plants at higher elevations in slope wetlands. There are four main groups of hydrophytes that found in wetland systems throughout the world.
Submerged water plants. This type of vegetation is found completely underwater. Submerged wetland vegetation can grow in saline and fresh-water conditions. Some species have underwater flowers, while others have long stems to allow the flowers to reach the surface. Examples include seagrasses and eelgrass. Floating water plants. Floating vegetation is usually small although it may take up a large surface area in a wetland system. These hydrophytes have small roots and are only found in slow-moving water with rich-nutrient level water Floating aquatic plants are a food resource for avian species.
Examples include water lilies lily pad and duckweed. Emergent water plants. Emergent water plants can be seen above the surface of the water but whose roots are completely submerged. Many have aerenchyma to transmit oxygen from the atmosphere to their roots.
Examples include cattails Typha and arrow arum Peltandra virginica. Surrounding trees and shrubs. Forested wetlands are generally known as swamps.
Fish: Fish are more dependent on wetland ecosystems than any other type of habitat. Amphibians: Frogs are the most crucial amphibian species in wetland systems. Frogs need both terrestrial and aquatic habitats in which to reproduce and feed. While tadpoles control algal populations, adult frogs forage on insects. Frogs are used as an indicator of ecosystem health due to their thin skin which absorbs both nutrient and toxins from the surrounding environment resulting in an above average extinction rate in unfavorable and polluted environmental conditions.
Reptiles: Alligators and crocodiles are two common reptilian species. Alligators are found in fresh water along with the fresh water species of the crocodile. The saltwater crocodile is found in estuaries and mangroves and can be seen in the coastline bordering the Great Barrier Reef in Australia. The Florida Everglades is the only place in the world where both crocodiles and alligators co-exist. Snapping turtles are one of the many kinds of turtles found in wetlands.
Mammals: Multiple small mammals as well as large herbivore and apex species such as the Florida Panther live within and around wetlands. The wetland ecosystem attracts mammals due to its prominent seed sources, invertebrate populations, and numbers of small reptiles and amphibians. Monotremes: The platypus Ornithorhynchus anatinus is found in eastern Australia living in freshwater rivers or lakes, and much like the beaver creates dams, create burrows for shelter and protection.
The platypus swims through the use of webbed feet. Platypuses feed on insect larvae, worms, or other freshwater insects hunting mainly by night by the use of their bill. They turn up mud on the bottom of the lake or river, and with the help of the electroreceptors located on the bill, unearth insects and freshwater insects. The platypus stores their findings in special pouches behind their bill and consumes its prey upon returning to the surface.
Insects and invertebrates: These species total more than half of the , known animal species in wetlands. Insects and invertebrates can be submerged in the water or soil, on the surface, and in the atmosphere.
Algae are diverse water plants that can vary in size, color, and shape. Algae occur naturally in habitats such as inland lakes, inter-tidal zones, and damp soil and provide a dedicated food source for animals, fish, and invertebrates.
There are three main groups of algae:. Plankton are algae which are microscopic, free-floating algae. This algae is so tiny that on average, if fifty of these microscopic algae were lined up end-to-end, it would only measure one millimetre. Plankton are the basis of the food web and are responsible for primary production in the ocean using photosynthesis to make food. Filamentous algae are long strands of algae cells that form floating mats. Chara and Nitella algae are upright algae that look like a submerged plant with roots.
Temperatures vary greatly depending on the location of the wetland. In these zones, summers are warm and winters are cold, but temperatures are not extreme. However, wetlands found in the tropic zone, around the equator, are warm year round. Wetlands are also located in every climatic zone. The amount of rainfall a wetland receives varies widely according to its area. Wetlands in Wales, Scotland, and Western Ireland typically receive about mm or 60 in per year.
In some places in Southeast Asia, where heavy rains occur, they can receive up to 10, mm about in. In the northern areas of North America, wetlands exist where as little as mm 7 inches of rain fall each year. Human-disturbance: [37]. In Southeast Asia, peatswamp forests and soils are being drained, burnt, mined, and overgrazed, contributing severely to climate change.
It decomposes and turns into carbon dioxide CO 2 , which is released into the atmosphere. Peat fires cause the same process to occur and in addition create enormous clouds of smoke that cross international borders, such as happens every year in Southeast Asia. Through the building of dams, Wetlands International is halting the drainage of peatlands in Southeast Asia, hoping to mitigate CO 2 emissions.
Concurrent wetland restoration techniques include reforestation with native tree species as well as the formation of community fire brigades. This sustainable approach can be seen in Central Kalimantan and Sumatra, Indonesia. Concerns are developing over certain aspects of farm fishing, which uses natural waterways to harvest fish for human consumption and pharmaceuticals.
This practice has become especially popular in Asia and the South Pacific. Its impact upon much larger waterways downstream has negatively affected many small island developing states.
The function of natural wetlands can be classified by their ecosystem benefits. United Nations Millennium Ecosystem Assessment and Ramsar Convention found wetlands to be of biosphere significance and societal importance in the following areas:.
Unless otherwise cited, Ecosystem services is based on the following series of references. Please select which cookies you would like to keep switched on. Open a list of all cookies. Below you can decide which type of cookies you would like to keep switched on.
Philip has travelled through Zambia several times and is the author of more than 20 guidebooks to various African destinations. Philip is the Zambia expert for SafariBookings and author of more than 20 guidebooks to Africa. Being in the tropics, Bangweulu Wetlands has a warm climate with a Wet and Dry season. The average temperature is uniform throughout the year, with a notable increase in temperature in October, before the rains. Nights are cool to cold in the Dry season months, from May to August.
There is almost no rain at all in the Dry season. It is warm during the day, but cool at night. The water levels recede, making game drives easier. The cats, which can grow to kilograms pounds , have been known to attack people in the swamp. Scientists and honey collectors are especially at risk. Marshes North and south of the tropics, swamps give way to marshes. These wetlands form a flat, grassy fringe near river mouths, in bays, and along coastlines.
Many are alternately flooded and exposed by the movement of tides. Like swamps, marshes are often divided into freshwater and saltwater categories. Freshwater Marshes Freshwater marshes, often found hundreds of kilometers from the coast, are dominated by grasses and aquatic plants. These marshes often develop around lakes and streams. Many freshwater marshes lie in the prairie pothole region of North America, the heart of which extends from central Canada through the northern Midwest of the United States.
Prairie potholes are bowl-shaped depressions left by chunks of glacial ice buried in the soil during the most recent ice age. When the ice melted, muddy water filled the potholes. Fertile soil and a temperate climate make these marshes some of the richest in the world.
For this reason, many prairie potholes have been drained and the land used for agriculture. Thousands of migratory birds depend on the remaining prairie potholes as they travel from the Arctic to more temperate climates every year.
Farther south, freshwater marshes form much of the Everglades, a huge wetland region in southern Florida. Water from Lake Okeechobee flows slowly through the Everglades on its way to the ocean.
Sawgrass, cypress, and mangroves grow along its path. The muddy, slow-moving water is also home to rare types of orchid. The Everglades are known for their diversity of wildlife. This marsh contains hundreds of species of wading birds, each of which is adapted to feed on insects, fish, clams, shrimp, or even rodents such as mice.
Alligators make their nests in the dense sawgrass, and swim in the murky water. Dominated by grasses, they provide food and shelter for algae, fungi, shellfish, fish, amphibians, and reptiles. Wading birds and other animals feed on the vegetation and abundant insects. The warm saltwater marshes of northern Australia are influenced by the tides of the Indian and Pacific oceans.
They often overlap with the freshwater marshes of rivers, such as the Jardine. A few mangrove trees may dot saltwater marshes, but they are dominated by grasses and a layer of algae called an algal mat. This algal mat is home to many insects and amphibians. Some of these birds nest in the shrubs and prey on insects and fish in the area.
Others are migratory, only visiting the marsh when their home ranges become too cold or dry to support life. These enormous reptiles often spend the wet season in freshwater swamps and rivers, and migrate to saltwater marshes in the dry season. Many Australian beaches have strict warnings to swimmers during certain seasons, because saltwater crocodiles are a threat to people as well.
Bogs Swamps and marshes are generally found in warm climates. They also exist at high altitudes in warmer regions, such as the Sierra Nevada in the United States.
Bogs are often called moors or fens in Europe, and muskegs in Canada. Like many wetlands, bogs develop in areas where the water table, or the upper surface of underground water, is high. They often begin in glacial depressions called kettle lake s, which are deeper than prairie potholes. A bog forms as a kettle lake gradually fills with plant debris. Leaves, roots, and stems of large plants accumulate on the bed of the lake.
As the lake becomes shallower, mosses and other plants growing along the edges of the lake extend into the water. Eventually, these plants are followed by water-loving grasses and sedges. Soon, the water is choked with vegetation. The oldest, partially decayed vegetation at the bottom of the bog forms a thick, spongy mat called peat. Peat is a valuable fuel in many parts of the world.
It is often the first step in the creation of coal , a fossil fuel. The fossils in coal are wetland plants. Some people living near bogs cut and dry squares of peat. It is burned for heating and cooking, or used to insulate buildings.
Bogs preserve more than the remains of plants, however. The bodies of dozens of prehistoric people have been found in bogs in Europe and Asia.
Bog bodies are in such excellent condition that anthropologist s can examine clothes, tattoos, and hair color, and even investigate a cause of death. Most people found in bogs were killed, though historians and anthropologists debate whether they were murdered or sacrifice d as part of a religious ritual. They are called quaking bogs because the surface quakes when a person walks on the spongy peat. The island of Ireland, with its cool, wet climate, has hundreds of quaking bogs.
Unlike other wetlands, bogs usually are not agriculturally fertile. The amount of acid in the soil and water is generally higher than that in swamps or marshes. The supply of nutrient s, especially nitrogen, is low. Only certain kinds of plants can grow in bogs. Some of the few plants harvested in the wet, acidic soil of bogs are cranberries and blueberries. Plants are autotroph s, meaning they are able to create their own food from air, water, and sunlight.
Many bog plants have adapted to the poor nutrients in the soil and water by expanding their food source. Pitcher plants and sundew, common in bogs, are carnivorous: They trap and consume insects. Because of the limited species of plants, bogs do not have the biodiversity common in other types of wetlands. Insects, common in all wetlands, include butterflies and dragonflies. These insects feed on the nectar in bog flowers. Ireland has dozens of native butterflies found in bogs.
Birds, such as geese and pheasant, also make their homes in the bog, although it is unusual to find larger animals. In North America, moose are one of the few large animals that thrive in bog habitats. Association of State Wetland Managers. November 15, On the challenges of modeling the net radiative forcing of wetlands: reconsidering Mitsch et al. Landscape Ecology , 29 4 , Errors in greenhouse forcing and soil carbon sequestration estimates in freshwater wetlands: a comment on Mitsch et al.
Landscape Ecology , 29 9 , Climate change and forests of the future: managing in the face of uncertainty. Ecological Applications , 17 8 , EPA Wildlife of riparian habitats. Johnson and T. O'Neil ed. How growing sea plants can help slow ocean acidification. Yale Environment Oceanography , 28 2 , Global change and terrestrial plant community dynamics.
Proceedings of the National Academy of Sciences , 14 , Amy Yahnke Senior Ecologist amy. Coastal wetlands will also be impacted by sea level rise and changes in water chemistry. Those changes can alter wetland conditions and processes, including the types of habitat they provide, and their ability to manage water quality and flooding.
Wetlands mitigate climate change Wetlands are a key player in global greenhouse gas budgets. Wetlands can be a source of some greenhouse gases, especially when disturbed, but they are also an important sink for greenhouse gases, where carbon is stored and prevented from entering the atmosphere. Wetlands and adaptation to climate change Many wetlands will play a role in our ability to manage risks from climate change.
Wetlands are dynamic systems that experience cycles of wet and dry phases on seasonal, annual, and decadal scales. Because of that natural variability, many wetlands may be able to persist and continue to provide ecosystem services despite climate change.
These ecosystem services include: Cleaning up polluted water. Slowing and storing floodwaters and snow melt.
0コメント