1.
Forest
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A forest is a large area dominated by trees. Hundreds of more precise definitions of forest are used throughout the world, incorporating factors such as density, tree height, land use, legal standing. According to the widely used Food and Agriculture Organization definition, forests covered four billion hectares or approximately 30 percent of the land area in 2006. Forests are the dominant terrestrial ecosystem of Earth, and are distributed across the globe, Forests account for 75% of the gross primary productivity of the Earths biosphere, and contain 80% of the Earths plant biomass. Forests at different latitudes and elevations form distinctly different ecozones, boreal forests near the poles, tropical forests near the equator, higher elevation areas tend to support forests similar to those at higher latitudes, and amount of precipitation also affects forest composition. Human society and forests influence each other in both positive and negative ways, Forests provide ecosystem services to humans and serve as tourist attractions. Forests can also affect peoples health, human activities, including harvesting forest resources, can negatively affect forest ecosystems. Although forest is a term of common parlance, there is no universally recognised precise definition, there are three broad categories of forest definitions in use, administrative, land use, and land cover. Land use definitions are based upon the purpose that the land serves. For example, a forest may be defined as any land that is used primarily for production of timber, land cover definitions define forests based upon the type and density of vegetation growing on the land. Such definitions typically define a forest as an area growing trees above some threshold and these thresholds are typically the number of trees per area, the area of ground under the tree canopy or the section of land that is occupied by the cross-section of tree trunks. Under such land cover definitions, and area of land only be defined as forest if it is growing trees, areas that fail to meet the land cover definition may be still included under while immature trees are establishing if they are expected to meet the definition at maturity. Under land use definitions, there is variation on where the cutoff points are between a forest, woodland, and savanna. Under some definitions, forests require high levels of tree canopy cover, from 60% to 100%, excluding savannas. Other definitions consider savannas to be a type of forest, the term was not endemic to Romance languages, and cognates in Romance languages, such as Italian foresta, Spanish and Portuguese floresta, etc. are all ultimately borrowings of the French word. The exact origin of Medieval Latin foresta is obscure, uses of the word forest in English to denote any uninhabited area of non-enclosure are now considered archaic. The word was introduced by the Norman rulers of England as a term denoting an uncultivated area legally set aside for hunting by feudal nobility. These hunting forests were not necessarily wooded much, if at all, however, as hunting forests did often include considerable areas of woodland, the word forest eventually came to mean wooded land more generally
2.
Fresh water
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Fresh water is generally characterized by having low concentrations of dissolved salts and other total dissolved solids. The term specifically excludes seawater and brackish water although it does include mineral-rich waters such as chalybeate springs, the term sweet water has been used to describe fresh water in contrast to salt water. The term fresh water does not have the meaning as potable water. Much of the fresh water and ground water is unsuitable for drinking without some form of purification because of the presence of chemical or biological contaminants. It may also be in contact with the underlying underground water. The majority of water on Earth is in ice caps. The source of almost all water is precipitation from the atmosphere, in the form of mist, rain. Fresh water falling as mist, rain or snow contains materials dissolved from the atmosphere and material from the sea, in some cases this acid rain results in pollution of lakes and rivers. In coastal areas fresh water may contain significant concentrations of salts derived from the sea if windy conditions have lifted drops of seawater into the rain-bearing clouds. This can give rise to elevated concentrations of sodium, chloride, magnesium, significant quantities of iron may be transported in this way including the well-documented transfer of iron-rich rainfall falling in Brazil derived from sand-storms in the Sahara in north Africa. Water is an issue for the survival of all living organisms. Some can use water but many organisms including the great majority of higher plants. Out of all the water on Earth, saline water in oceans, seas and saline groundwater make up about 97% of it. Freshwater lakes contain about 87% of this surface water, including 29% in the African Great Lakes, 20% in Lake Baikal in Russia, 21% in the North American Great Lakes. Swamps have most of the balance only a small amount in rivers. In areas with no water on the ground surface, fresh water derived from precipitation may, because of its lower density. Most of the fresh water is frozen in ice sheets. Many areas suffer from lack of distribution of water, such as deserts
3.
River
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A river is a natural flowing watercourse, usually freshwater, flowing towards an ocean, sea, lake or another river. In some cases a river flows into the ground and becomes dry at the end of its course without reaching another body of water, small rivers can be referred to using names such as stream, creek, brook, rivulet, and rill. There are no official definitions for the term river as applied to geographic features. Many names for small rivers are specific to geographic location, examples are run in parts of the United States, burn in Scotland and northeast England. Sometimes a river is defined as being larger than a creek, but not always, Rivers are part of the hydrological cycle. Potamology is the study of rivers while limnology is the study of inland waters in general. Extraterrestrial rivers of liquid hydrocarbons have recently found on Titan. Channels may indicate past rivers on other planets, specifically outflow channels on Mars and rivers are theorised to exist on planets, a river begins at a source, follows a path called a course, and ends at a mouth or mouths. The water in a river is confined to a channel. In larger rivers there is also a wider floodplain shaped by flood-waters over-topping the channel. Floodplains may be wide in relation to the size of the river channel. This distinction between river channel and floodplain can be blurred, especially in areas where the floodplain of a river channel can become greatly developed by housing. Rivers can flow down mountains, through valleys or along plains, the term upriver refers to the direction towards the source of the river, i. e. against the direction of flow. Likewise, the term describes the direction towards the mouth of the river. The term left bank refers to the bank in the direction of flow. The river channel typically contains a stream of water, but some rivers flow as several interconnecting streams of water. Extensive braided rivers are now found in only a few regions worldwide and they also occur on peneplains and some of the larger river deltas. Anastamosing rivers are similar to braided rivers and are quite rare
4.
Lake
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A lake is an area of variable size filled with water, localized in a basin, that is surrounded by land, apart from any river or other outlet that serves to feed or drain the lake. Lakes lie on land and are not part of the ocean, and therefore are distinct from lagoons, Lakes can be contrasted with rivers or streams, which are usually flowing. Most lakes are fed and drained by rivers and streams, natural lakes are generally found in mountainous areas, rift zones, and areas with ongoing glaciation. Other lakes are found in endorheic basins or along the courses of mature rivers, in some parts of the world there are many lakes because of chaotic drainage patterns left over from the last Ice Age. All lakes are temporary over geologic time scales, as they will fill in with sediments or spill out of the basin containing them. The word lake comes from Middle English lake, from Old English lacu, from Proto-Germanic *lakō, cognates include Dutch laak, Middle Low German lāke as in, de, Moorlake, de, Wolfslake, de, Butterlake, German Lache, and Icelandic lækur. Also related are the English words leak and leach, none of these definitions completely excludes ponds and all are difficult to measure. For this reason, simple size-based definitions are used to separate ponds. One definition of lake is a body of water of 2 hectares or more in area, however, others have defined lakes as waterbodies of 5 hectares and above, or 8 hectares and above. Charles Elton, one of the founders of ecology, regarded lakes as waterbodies of 40 hectares or more. The term lake is used to describe a feature such as Lake Eyre. In common usage, many bear names ending with the word pond. One textbook illustrates this point with the following, In Newfoundland, for example, almost every lake is called a pond, whereas in Wisconsin, the majority of lakes on Earth are fresh water, and most lie in the Northern Hemisphere at higher latitudes. Canada, with a drainage system has an estimated 31,752 lakes larger than 3 square kilometres and an unknown total number of lakes. Finland has 187,888 lakes 500 square metres or larger, most lakes have at least one natural outflow in the form of a river or stream, which maintain a lakes average level by allowing the drainage of excess water. Some lakes do not have an outflow and lose water solely by evaporation or underground seepage or both. Many lakes are artificial and are constructed for power generation, aesthetic purposes, recreational purposes, industrial use. Globally, lakes are greatly outnumbered by ponds, of an estimated 304 million standing water bodies worldwide, 91% are 1 hectare or less in area
5.
Swamp
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A swamp is a wetland that is forested. Many swamps occur along rivers where they are critically dependent upon natural water level fluctuations. Other swamps occur on the shores of large lakes, some swamps have hammocks, or dry-land protrusions, covered by aquatic vegetation, or vegetation that tolerates periodic inundation. The two main types of swamp are true or swamp forests and transitional or shrub swamps, in the boreal regions of Canada, the word swamp is colloquially used for what is more correctly termed a bog or muskeg. The water of a swamp may be water, brackish water or seawater. Some of the worlds largest swamps are found along rivers such as the Amazon, the Mississippi. Swamps are characterized by slow-moving to stagnant waters and they are usually associated with adjacent rivers or lakes. Swamps are features of areas with very low topographic relief, historically, humans have drained swamps to provide additional land for agriculture and to reduce the threat of diseases borne by swamp insects and similar animals. Many swamps have also undergone intensive logging, requiring the construction of drainage ditches and these ditches and canals contributed to drainage and, along the coast, allowed salt water to intrude, converting swamps to marsh or even to open water. Large areas of swamp were therefore lost or degraded, louisiana provides a classic example of wetland loss from these combined factors. Europe has probably lost nearly half its wetlands, New Zealand lost 90 percent of its wetlands over a period of 150 years. Ecologists recognise that swamps provide valuable ecological services including flood control, fish production, water purification, carbon storage, in many parts of the world authorities protect swamps. In parts of Europe and North America, swamp restoration projects are becoming widespread, often the simplest steps to restoring swamps involve plugging drainage ditches and removing levees. Swamps and other wetlands have traditionally held a very low property value compared to fields, prairies and they have a reputation for being unproductive land that cannot easily be utilized for human activities, other than perhaps hunting and trapping. Farmers, for example, typically drained swamps next to their fields so as to more land usable for planting crops. Many societies now realize that swamps are important to providing fresh water and oxygen to all life. Indeed, floodplain swamps are important in fish production. Government environmental agencies are taking steps to protect and preserve swamps, in Europe, major effort is being invested in the restoration of swamp forests along rivers
6.
Temperate climate
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In geography, temperate or tepid latitudes of Earth lie between the tropics and the polar regions. The temperatures in these regions are relatively moderate, rather than extremely hot or cold. The north temperate zone extends from the Tropic of Cancer to the Arctic Circle, the south temperate zone extends from the Tropic of Capricorn to the Antarctic Circle. In some climate classifications, the zone is often divided into several smaller climate zones. These include Humid subtropical climate, Mediterranean climate, oceanic, subtropical climates are located between 23. 5° and 35. 0° north or south latitude on the eastern or leeward sides of landmasses. This climate has long, generally hot, summers and short, mild winters and these climates may occur in southern Asia, the southeastern United States, parts of eastern Australia, and in eastern coastal South America. Mediterranean climates, occur between 30° and 42° north and south latitude, on the sides of landmasses. This climate has hot summers and short mild winters, however, seasonal rainfall is the opposite of that of the subtropical humid type. These climates occur near the rimlands of the Mediterranean Sea, in western Australia, in California, the oceanic climates occur in the higher middle latitudes, between 45° and 60° north and south latitude. They are created by the flow from the cool high latitude oceans to their west. This causes the climate to have cool summers and cool winters, annual rainfall is spread throughout the entire year. Regions with this climate include Western Europe, northwestern North America, the Continental climates occur in middle latitudes, between 35° or 40° to 55°. These climates are normally inland or on sides of landmasses. They feature warm to hot summers and cold winters, with a large temperature variation. Regions with this climate include northern temperate Asia, the northern United States, southern Canada, the vast majority of the worlds human population resides in temperate zones, especially in the northern hemisphere, due to its greater mass of land. The richest temperate flora in the world is found in southern Africa, geographical zone Habitat Köppen climate classification Middle latitudes Polar circle Subtropics
7.
Subtropics
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The subtropics are geographic and climate zones located roughly between the tropic circle of latitude at 23.5 latitude and temperate latitudes. Subtropical climates are characterized by warm to hot summers and cool to mild winters with infrequent frost. Subtropical climates can occur at elevations within the tropics, such as in the southern end of the Mexican Plateau and in Vietnam. Six climate classifications use the term to define the various temperature. A great portion of the deserts are located within the subtropics. Within savanna regimes in the subtropics, a wet season is seen annually during the summer, within Mediterranean climate regimes, the wet season occurs during the winter. Areas bordering warm oceans are prone to heavy rainfall from tropical cyclones. Plants such as palms, citrus, mango, lychee, the tropics have been historically defined as lying between the Tropic of Cancer and Tropic of Capricorn, located at 23. 45° north and south latitude respectively. The poleward fringe of the subtropics is located at approximately 40° north and south latitude respectively, northern fringes of the type can go further north due to moderating effects of ocean streams, like in parts of Southern Europe due to heat transported by the Gulf Stream. Several methods have used to define the subtropical climate. In the Trewartha climate classification, a subtropical region should have at least eight months with a temperature greater than 10 °C. According to the Troll-Paffen climate classification, there exists one large subtropical zone named the warm-temperate subtropical zone. According to the E. Neef climate classification, the zone is divided into two parts, Rainy winters of the west sides and Eastern subtropical climate. According to the Wilhelm Lauer & Peter Frankenberg climate classification, the zone is divided into three parts, high-continental, continental, and maritime. According to the Siegmund/Frankenberg climate classification, subtropical is one of six zones in the world. Heating of the earth near the equator leads to large amounts of upward motion and convection along the trough or Intertropical convergence zone. The upper-level divergence over the near-equatorial trough leads to air rising and moving away from the equator aloft, as the air moves towards the Mid-Latitudes, it cools and sinks, which leads to subsidence near the 30th parallel of both hemispheres. This circulation is known as the Hadley cell and leads to the formation of the subtropical ridge, many of the worlds deserts are caused by these climatological high-pressure areas, located within the subtropics
8.
Tropics
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The tropics are a region of the Earth surrounding the equator. The tropics are also referred to as the zone and the torrid zone. The tropics include all the areas on the Earth where the Sun is at a point directly overhead at least once during the solar year. The tropics are distinguished from the climatic and biomatic regions of Earth, which are the middle latitudes. Tropical is sometimes used in a sense for a tropical climate to mean warm to hot and moist year-round. Many tropical areas have a dry and wet season, the wet season, rainy season or green season, is the time of year, ranging from one or more months, when most of the average annual rainfall in a region falls. Areas with wet seasons are disseminated across portions of the tropics and subtropics, under the Köppen climate classification, for tropical climates, a wet season month is defined as a month where average precipitation is 60 millimetres or more. Tropical rainforests technically do not have dry or wet seasons, since their rainfall is distributed through the year. When the wet season occurs during the season, or summer, precipitation falls mainly during the late afternoon. The wet season is a time when air quality improves, freshwater quality improves and vegetation grows significantly, floods cause rivers to overflow their banks, and some animals to retreat to higher ground. Soil nutrients diminish and erosion increases, the incidence of malaria increases in areas where the rainy season coincides with high temperatures. Animals have adaptation and survival strategies for the wetter regime, unfortunately, the previous dry season leads to food shortages into the wet season, as the crops have yet to mature. Regions within the tropics may well not have a tropical climate, there are alpine tundra and snow-capped peaks, including Mauna Kea, Mount Kilimanjaro, and the Andes as far south as the northernmost parts of Chile and Argentina. Under the Köppen climate classification, much of the area within the tropics is classed not as tropical but as dry including the Sahara Desert. Tropical plants and animals are those native to the tropics. Tropical ecosystems may consist of rainforests, dry forests, spiny forests, desert. There are often significant areas of biodiversity, and species present, particularly in rainforests. In biogeography, the tropics are divided into Paleotropics and Neotropics, together, they are sometimes referred to as the Pantropic
