Wetland Introduction

Wetland is a transitional zone between terrestrial ecosystems and aquatic ecosystems. In a specific environment where the soil is immersed in water, many wetland characteristic plants grow. Wetlands are widely distributed around the world and contain numerous wildlife resources and are important ecosystems. The breeding and migration of many rare waterfowl are inseparable from wetlands, so wetlands are called "bird paradise." Wetlands have a powerful ecological purification effect, so they are also known as the "kidneys of the earth". Under the dual pressure of population explosion and economic development, a large number of wetlands were transformed into farmland in the mid-to-late 20th century. Coupled with excessive resource development and pollution, the area of ??wetlands was greatly reduced, and wetland species were severely damaged.

Wetlands are multi-functional and biologically diverse ecosystems on earth, and are one of the most important living environments for humans.

There are many types of wetlands, usually divided into two categories: natural and artificial. Natural wetlands include swamps, peatlands, lakes, rivers, beaches and salt marshes, while artificial wetlands mainly include rice fields, reservoirs, ponds, etc. According to statistics, there are 8.558 million square kilometers of natural wetlands in the world, accounting for 6.4% of the land area.

Wetlands are the richest in biological diversity

There are more than 2,760 species of wetland plants recorded in my country alone, including 156 families, 437 genera, and more than 1,380 species of higher wetland plants. From the perspective of growth environment, wetland plants can be divided into three categories: aquatic, marshy, and hygrophytic; from the perspective of plant life types, there are emergent types, floating leaf types, submerged types, and floating types; from the perspective of plant types, some are thin and weak. Some of the grasses are thick herbs, some are short shrubs, and some are tall trees. The types of wetland animals are also extremely rich. There are about 1,500 species of wetland animals recorded in my country (excluding insects, invertebrates, fungi and microorganisms), including about 250 species of water and about 1,040 species of fish. There are about 500 species of freshwater fish among fish, accounting for more than 80% of the total number of freshwater fish in the world. Therefore, wetlands are the most valuable and productive ecosystems from both economic and ecological perspectives.

Wetlands are basically divided into five categories

Sea areas

Subtidal waters: permanently shallow waters with a water depth of less than 6 meters at low tide, including bays and Channel; subtidal aquatic vegetation layer, including various seagrasses and tropical marine meadows; coral reefs.

Intertidal waters: rocky beaches, including reef cliffs and rocky beaches; gravel beaches; intertidal silt sand and salt-alkali beaches without vegetation; intertidal sedimentary beaches with vegetation, including on the continental shelf of mangroves.

Estuary

Subtidal estuary: Estuary waters are the permanent waters of estuaries and delta estuary systems.

Intertidal estuary: intertidal mud, sand or salt flats with sparse vegetation; intertidal marshes include saline meadows, tidal semi-saline marshes and freshwater marshes; intertidal forested wetlands include mangroves , nippa palm and tidal freshwater swamp forest.

Lagoon Wetland: A brackish to saline lake with one or more narrow channels connected to the sea.

Salt lakes (inland drainage areas): Permanent and seasonal saltwater or alkaline lakes, mudflats and swamps.

Rivers

Permanent rivers: Permanent rivers and streams, including waterfalls; inland deltas.

Ephemeral rivers: Seasonally and intermittently flowing rivers and streams; river floodplains, including river flats, flood valleys, and seasonally flooded meadows.

Lake

Permanent lakes: permanent freshwater lakes (above 8km2), including lakeshores that are seasonally or intermittently flooded; permanent freshwater ponds (above 8km2) .

Seasonal lakes: seasonal freshwater lakes (above 8km2), including flood plain lakes.

Artificial water surfaces

Such as reservoirs, ponds, rice fields, etc. belong to the generalized wetland and are recognized by the Ramsar Convention.

The functions of wetlands are multi-faceted

It can be used as a direct water source or to supplement groundwater. It can also effectively control floods and prevent soil desertification, and it can also retain sediments and toxic substances. , nutrients, thereby improving environmental pollution; it can store carbon elements in the form of organic matter, reduce the greenhouse effect, protect the coast from wind and wave erosion, and provide a clean and convenient transportation method... It is known for its many valuable and beneficial functions. It is called the "Kidney of the Earth". Wetlands are also a paradise for the growth of many plants and animals, especially waterfowl. At the same time, they provide humans with food (aquatic products, livestock products, grains), energy (water energy, peat, firewood), and raw materials (reeds, wood, medicinal plants). ) and tourist places are an important foundation for human survival and sustainable development.

Material production function

Wetlands have powerful material production functions and contain rich animal and plant resources. The Qilihai Marsh Wetland is an important feed base and source of primary productivity in the coastal areas of Tianjin. According to preliminary surveys, before the 1970s, there were more than 100 species of aquatic and hygrophytic plant communities in Qilihai, including about 40 species with ecological value. There are about 10 species of mammals and more than 30 species of fish and crabs. As the most typical plant in the Qilihai Wetland, reed covers an area of ??7186 hectares and has high economic and ecological value. It is not only an important raw material for the paper industry, but also an important resource for agriculture, salt industry, fishery, breeding industry, and weaving industry. Important means of production can also play a role in preventing wind and floods, improving the environment, improving soil, purifying water quality, preventing pollution, and regulating ecological balance. In addition, the usable water surface of Qilihai reaches 10,000 acres, with an annual output of 2,000 tons of crabs. It is the famous origin of Qilihai crabs.

Atmospheric component adjustment function

The rich plant community in the wetland can absorb a large amount of carbon dioxide gas and release oxygen. Some plants in the wetland also have the ability to absorb harmful gases in the air. Function, can effectively adjust atmospheric components. However, it must also be noted that wetland habitats also emit greenhouse gases such as methane and ammonia. Swamps have great biological production efficiency. During the formation of organic matter, plants continuously absorb CO2 and other gases, especially some harmful gases. The oxygen in the swamp is rarely consumed by the decomposition of dead plant remains. Swamps can also absorb dust and various bacteria carried in the air, thereby purifying the air. In addition, swamp deposits have great adsorption capacity. Sewage or industrial wastewater containing heavy metals can absorb metal ions and harmful components through swamps.

Water regulation function

Wetlands play an important role in water storage, regulating river runoff, recharging groundwater and maintaining regional water balance. They are natural "sponges" for water storage and flood control. Precipitation can be distributed unevenly in time and space, and flood and drought disasters can be avoided through the adjustment of wetland throughput. Qilihai Wetland is an important flood storage and detention area in the Tianjin Coastal Plain, with a safe flood storage depth of 3.5-4m.

Marsh wetlands have the function of humidifying the climate and purifying the environment, and are an important part of the ecosystem. Most of them develop in the negative landform type, where water accumulates for a long time, and dense plants grow, with roots and stems intertwined underneath and debris accumulated. Submerged swamps generally have a grass root layer of several tens of centimeters. The grass root layer is loose and porous and has a strong water-holding capacity. It can hold water 3 to 15 times greater than its absolute dry weight. Not only can it store a large amount of water, but it can also continuously return water to the atmosphere through plant transpiration and water evaporation, thereby increasing air humidity, regulating precipitation, and playing a good role in the natural cycle of water. According to experimental research, one hectare of swamp can evaporate 7,415 tons of water during the growing season, which shows its huge function in regulating climate.

Purification function

Swamp wetlands act like natural filters, which help slow down the flow of water that contains toxins and impurities (pesticides, domestic sewage and industrial emissions). When passing through wetlands, slowing down the flow rate is conducive to the precipitation and elimination of poisons and impurities. Some wetland plants can effectively absorb toxic substances in the water and purify the water quality.

Swamps and wetlands can decompose and purify environmental substances, and play the role of "detoxification" and "detoxification", so they are known as the "kidneys of the earth". If there were no wetlands, it would be like a person having his kidneys cut off.

For example, nitrogen, phosphorus, potassium and other organic substances are stored by organisms through complex physical and chemical changes, or are permanently stored through biological transfer (such as harvesting plants, fishing, etc.) out of the wetland and participate in a larger cycle.

There are a considerable number of aquatic plants in swamp wetlands, including emergent, floating and submersible plants. They have a strong ability to remove poisons and are the nemesis of poisons. It has been determined that the concentration of heavy metals concentrated in wetland plant tissues is more than 100,000 times higher than the concentration in the surrounding water. Because of this, people often use the ecological function of wetland plants to purify viruses in pollutants, effectively removing "toxins" in sewage and achieving the purpose of purifying water quality.

For example, water hyacinth, cattails and reeds are widely used to treat sewage and absorb heavy metals such as cadmium, copper and zinc in high concentrations in sewage. In Florida, the United States, someone conducted the following experiment. Before discharging wastewater into a river, it was first allowed to flow through a cypress swamp (a type of wetland). After measurement, it was found that approximately 98% of nitrogen and 97% of phosphorus were absorbed into the river. Purification is eliminated, and the amazing ability of wetlands to remove pollutants is evident. In the city of Kalkuta in India, there is a sewage treatment plant in the city. All domestic sewage is discharged into the constructed wetland in the eastern suburbs. The cost of sewage treatment is quite low, which has become a global model.

Provide animal habitat functions

The complex and diverse plant communities of wetlands provide good habitats for wild animals, especially some rare or endangered wild animals, and are ideal habitats for birds and amphibians. A place where animals breed, inhabit, migrate and overwinter.

Although the special natural environment of swamp wetlands is conducive to the growth of some plants, it is not an ideal home for mammal populations, but birds can get special enjoyment here. Because the swamp environment covered with water and grass provides rich food sources and good conditions for various birds to build nests and avoid enemies.

Birds that inhabit and appear in the wetland all year round include swans, white storks, pelicans, wild geese, egrets, goshawks, floating gulls, herring gulls, terns, reed warblers, grazing birds, etc. About 200 kind. Moreover, the wetland is a stopover for birds from Siberia and Northeastern regions migrating southward for the winter.

Adjust local microclimate

Wetland water evaporates into water vapor, and then falls to the surrounding areas in the form of precipitation, maintaining local humidity and rainfall, making Ninghe County a Tianjin It is one of the areas with a relatively humid climate in the city.

Different definitions

Due to the lack of clear boundaries between wetlands, water and land, and the different research focuses of different disciplines on wetlands, there have always been differences in the definition of wetlands.

The Ramsar Convention adopts a broad definition of wetlands, which refers to swamps, wetlands, peatlands or water areas, whether natural or artificial, permanent or temporary, with static or flowing water, or Bodies of fresh, brackish or salt water, including waters whose depth at low tide does not exceed six meters. This definition includes the narrow sense wetland area, which is conducive to forming a narrow sense wetland and nearby water bodies and land into a whole for easy protection and management.

Wetland research activities tend to adopt a narrow definition.

In 1979, the U.S. Fish and Wildlife Service redefined wetlands in the article "Classification of Deep-water Wetland Habitats in the United States" as: "the intersection of land and water, where the water level is close to or at the surface of the ground, or there is a shallow Stratified water has at least one or more of the following characteristics:

(1) Aquatic plants are the dominant plant species at least periodically;

(2) The subsoil is mainly wet soil ;

(3) During the annual growing season, the bottom layer is sometimes submerged by water. "The definition also refers to the boundary between lakes and wetlands at a water depth of 2 meters at low water levels. According to this definition of wetlands, the world's wetlands can be divided into. With more than twenty types, this definition is currently accepted by wetland researchers in many countries.

The hydrological conditions of wetlands are the decisive factor in wetland attributes. The source of water (such as precipitation, groundwater, tides, rivers, lakes, etc.), water depth, flow patterns, and the duration and frequency of flooding determine the diversity of wetlands. Water has a profound impact on wetland soil development. Wetland soil is often called wet soil or Hydric Soil.

Others

The largest wetland in the world is the Pantanal in Mato Grosso state in central Brazil, covering an area of ??25 million hectares.

Wetland Science and Publications

Wetland Ecology Water Ecology "Wetlands" "Wetland Science" (Wetland Science, Magazine, China)

International Treaties and Organizations

International Convention on Wetlands (Ramsar Convention) World Wetland Day (World Wetland Day, June 5 every year)

Wetlands International (Wetlands International) The Society of Wetland Scientists International Council for Bird Preservation (ICBP)

International waterfowl and wetland re-search bureau )

Man and the Biosphere Northeast Asia Crane Reserve Network East Asia-Australia Wader Conservation Network

Geese and Ducks Migration Network

Scientific Research Institutions

Australia:

Australian Wetland Center Wetland Ecology Research Center, University of New South Wales

United States:

National Wetland Research Center (NWRC) Florida State University Wetland Research Center