World Wide Fund for Nature's full definition of an ecoregion, which is widely accepted and used, is the following:
The "Global 200" is the list of ecoregions identified by the World Wide Fund for Nature (WWF) as priorities for conservation.
A terrestrial ecoregion is a certain area of land which is different from the area near it. It has a distinct climate, geology, type of soil, water availability, and distinct living species (the animals and plants that live in the ecoregion).
For example, one ecoregion can be a desert. It would have sand, very little water, very hot temperatures during the day and very cold at night. The plants could be just bushes, small trees, cactii. The animals could be scorpions, little mammals, spiders.
Or for example, an ecoregion could be a tropical forest It would have warm temperatures all day, a lot of rainfall all year, a huge river crossing, and a very organic soil. The plants could be huge trees or ferns. The animals could be insects, birds, fish and apes.
Marine ecoregions are regions of the world's oceans, that are defined by the WWF, to help activities for saving marine ecosystems.
The scheme used to find out these ecoregions is more or less the same as that for terrestrial ecoregions. Major habitat types are identified: polar, temperate shelfs and seas, temperate upwelling, tropical upwelling, tropical coral, pelagic, abyssal, and hadal (ocean trench) — which correspond to the terrestrial biomes. Major biogeographic realms, analogous to the seven terrestrial ecozones, represent large regions of the ocean basins: North Temperate Atlantic, Eastern Tropical Atlantic, Western Tropical Atlantic, South Temperate Atlantic, North Temperate Indo-Pacific, Central Indo-Pacific, Eastern Indo-Pacific, Western Indo-Pacific, South Temperate Indo-Pacific, Southern Ocean, Antarctic, Arctic, and Mediterranean.
The classification of Marine ecoregions is not developed to the same level of detail and comprehensiveness as that of the terrestrial ecoregions; only the priority conservation areas of the Global 200 are listed.
See Global 200 Marine ecoregions for a full list of marine ecoregions (World Wide Fund for Nature).
Freshwater ecoregions are the freshwater habitats of a particular geographic area, including rivers, streams, lakes, and wetlands. Freshwater ecoregions are distinct from terrestrial ecoregions, which have biotic communities of the land, and marine ecoregions, which are biotic communities of the oceans.
The WWF speaks of seven major habitat types of freshwater ecoregions: Large rivers, large river headwaters, large river deltas, small rivers, large lakes, small lakes, and xeric basins.
Several freshwater ecoregions are listed in the Global 200, the WWF's priority ecoregions for conservation of biodiversity.
Wetland
In physical geography, a wetland is an environment that combines the properties of land and water. Wetlands are a distinct kind of ecosystem.
The combination of wet and dry areas means that many more different kinds of plants, animals and insects may live in a wetland than compared to other types of habitat. Because of this great biodiversity, several important wetlands are among the Global 200 ecoregions that the World Wide Fund for Nature listed for conservation to try to get people to protect them. As well, Ramsar Convention is adopted in 1971 for protection of wetland.
Marsh
In geography, a marsh is a type of wetland. It has grasses, rushes, reeds, typhas, sedges, and other herbaceous plants (possibly with low-growing woody plants) in a context of shallow water. A marsh is different from a swamp, which has a greater proportion of open water surface, which is generally deeper than a marsh. In the US, the term 'swamp' is used for wetland dominated by trees rather than grasses and low herbs.
The water of a marsh can be fresh, brackish or saline. Coastal marshes may be associated with estuaries and along waterways between coastal barrier islands and the inner coast. Estuarine marshes often are based on soils consisting of sandy bottoms or bay muds.
Marshes are critically important wildlife habitat, often serving as breeding grounds for a wide variety of animal life.
Ulan-Ude
Ulan-Ude (Russian:Ула́н-Удэ́; Buryat: Улаан-Үдэ), formerly Verkhneudinsk (), the capital city of the Buryat Republic, Russia. The city is located about 100 km south-east of Lake Baikal. It sits at the foot of the Khamar-Daban and Khrebet Ulan-Burgasy mountain ranges, next to the confluence of the Selenga River and its tributary, the Uda. The city is divided into two parts by the Uda. Population 359,391 (2002 Census); 352,530 (1989 Census). It is the third largest city in East Siberia. It is served by Ulan-Ude Airport (Mukhino) as well as the smaller Ulan-Ude Vostochny Airport.
Ulan-Ude was founded in 1666 by the Russian Cossacks. Due to its geographical position, the city grew rapidly and became a large trade centre which connected Russia with China and Mongolia. There are old merchants' mansions richly decorated with wood and stone carving in the historical center of Ulan-Ude, along the river banks. They represent beautiful examples of Russian classicism. There is also a large and highly unusual head of Lenin in the central square.
Pelagic zone
The pelagic zone is the open sea or ocean that is not near the coast. The name comes from the Greek πέλαγος ("pélagos"), which might be translated as "open sea".
To make this clear, seas around continents have continental crust beneath them. They are shallow. Seas away from continents can be very deep, and do not have continental shelves beneath them.
The pelagic (or open ocean) zone is divided into a number of sub-zones:
The last three zones are similar in character, and some marine biologists count them as a single zone or consider the latter two to be the one zone. Some define the hadopelagic as waters below 6000 meters, whether in a trench or not.
Vitamin A
Vitamin A is a vitamin, a group of organic chemicals including retinal and several carotenoids. The human body does not make these chemicals, and must take them from food. Egg yolks and liver are both rich in vitamin A. Many parts of the body need vitamin A. For example, vitamin A helps sight and is good for the immune system. It is also important for a growing embryo.
β-carotene, a provitamin found in foods like carrots can be converted to vitamin A. The efficiency of the conversion depends on genetics and fat consumption.
Too little vitamin A is dangerous to health. People who do not get enough of the vitamin may lose the ability to see in poor light and suffer from a weakened immune system. They may also have problems with memory, because vitamin A is important for the brain. People with malnutrition often have too little vitamin A. This is common in poor countries.
Too much vitamin A is also dangerous to one's health. It is a condition known as hypervitaminosis. Vitamin A is not soluble in water, and the human body can not get rid of the excess vitamin A easily by urination. Too much vitamin A can make someone very sick. People may get too much vitamin A from taking too many vitamin pills or from eating too much A-rich food like liver.
What applies to humans applies to all mammals at least. Some large predators, such as the big cats, seem not to eat their preys' livers. On the other hand, polar bears apparently do so, and they store vitamin A in their liver cells. However, they have long, sometimes very long, periods between kills. In contrast, African big cats kill about every three or four days, and they do seem to avoid eating the preys' livers.
Vitamin D
Vitamin D is a hormone. It is a steroid which is made in the body under the right conditions. Its making by the body needs sunlight, which acts on the lower layers of the skin.