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82-587: A bay can be the estuary of a river, such as the Chesapeake Bay , an estuary of the Susquehanna River . Bays may also be nested within each other; for example, James Bay is an arm of Hudson Bay in northeastern Canada . Some large bays, such as the Bay of Bengal and Hudson Bay, have varied marine geology . The land surrounding a bay often reduces the strength of winds and blocks waves . Bays may have as wide

164-829: A 3.2% rise in global deforestation. Massive wildfires in Canada , exacerbated by climate change , contributed to a 24% increase in global tree cover loss, highlighting the ongoing threats to forests essential for carbon storage and biodiversity . Despite some progress, the overall trends in forest destruction and climate impacts remain off track. The IPCC Sixth Assessment Report stated in 2022: “Over 420 million ha of forest were lost to deforestation from 1990 to 2020; more than 90% of that loss took place in tropical areas (high confidence), threatening biodiversity, environmental services, livelihoods of forest communities and resilience to climate shocks (high confidence).” See also: Global deforestation sharply accelerated around 1852. As of 1947,

246-421: A free connection to the open sea . Estuaries form a transition zone between river environments and maritime environments and are an example of an ecotone . Estuaries are subject both to marine influences such as tides , waves , and the influx of saline water , and to fluvial influences such as flows of freshwater and sediment. The mixing of seawater and freshwater provides high levels of nutrients both in

328-573: A harsh environment for organisms. Sediment often settles in intertidal mudflats which are extremely difficult to colonize. No points of attachment exist for algae , so vegetation based habitat is not established. Sediment can also clog feeding and respiratory structures of species, and special adaptations exist within mudflat species to cope with this problem. Lastly, dissolved oxygen variation can cause problems for life forms. Nutrient-rich sediment from human-made sources can promote primary production life cycles, perhaps leading to eventual decay removing

410-529: A number of coastal water bodies such as coastal lagoons and brackish seas. A more comprehensive definition of an estuary is "a semi-enclosed body of water connected to the sea as far as the tidal limit or the salt intrusion limit and receiving freshwater runoff; however the freshwater inflow may not be perennial, the connection to the sea may be closed for part of the year and tidal influence may be negligible". This broad definition also includes fjords , lagoons , river mouths , and tidal creeks . An estuary

492-408: A type of ecosystem in some estuaries that have been negatively impacted by eutrophication. Cordgrass vegetation dominates the salt marsh landscape. Excess nutrients allow the plants to grow at greater rates in above ground biomass, however less energy is allocated to the roots since nutrients is abundant. This leads to a lower biomass in the vegetation below ground which destabilizes the banks of

574-496: A variety of shoreline characteristics as other shorelines. In some cases, bays have beaches , which "are usually characterized by a steep upper foreshore with a broad, flat fronting terrace". Bays were significant in the history of human settlement because they provided easy access to marine resources like fisheries . Later they were important in the development of sea trade as the safe anchorage they provide encouraged their selection as ports . The United Nations Convention on

656-550: A well-mixed water column and the disappearance of the vertical salinity gradient . The freshwater-seawater boundary is eliminated due to the intense turbulent mixing and eddy effects . The lower reaches of Delaware Bay and the Raritan River in New Jersey are examples of vertically homogeneous estuaries. Inverse estuaries occur in dry climates where evaporation greatly exceeds the inflow of freshwater. A salinity maximum zone

738-436: A wholly marine embayment to any of the other estuary types. The most important variable characteristics of estuary water are the concentration of dissolved oxygen, salinity and sediment load. There is extreme spatial variability in salinity, with a range of near-zero at the tidal limit of tributary rivers to 3.4% at the estuary mouth. At any one point, the salinity will vary considerably over time and seasons, making it

820-470: A wide effect on the surrounding water bodies.  In turn, this can decrease fishing industry sales in one area and across the country. Production in 2016 from recreational and commercial fishing contributes billions of dollars to the United States' gross domestic product (GDP). A decrease in production within this industry can affect any of the 1.7 million people the fishing industry employs yearly across

902-455: Is a dynamic ecosystem having a connection to the open sea through which the sea water enters with the rhythm of the tides . The effects of tides on estuaries can show nonlinear effects on the movement of water which can have important impacts on the ecosystem and waterflow. The seawater entering the estuary is diluted by the fresh water flowing from rivers and streams. The pattern of dilution varies between different estuaries and depends on

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984-407: Is agreement that destruction of rainforests remains a significant environmental problem. The rate of net forest loss declined from 7.8 million ha per year in the decade 1990–2000 to 5.2 million ha per year in 2000–2010 and 4.7 million ha per year in 2010–2020. The rate of decline of net forest loss slowed in the most recent decade due to a reduction in the rate of forest expansion. In many parts of

1066-754: Is around 38%. Since 1960, roughly 15% of the Amazon has been removed with the intention of replacing the land with agricultural practices. It is no coincidence that Brazil has recently become the world's largest beef exporter at the same time that the Amazon rainforest is being clear cut. Another prevalent method of agricultural deforestation is slash-and-burn agriculture , which was primarily used by subsistence farmers in tropical regions but has now become increasingly less sustainable. The method does not leave land for continuous agricultural production but instead cuts and burns small plots of forest land which are then converted into agricultural zones. The farmers then exploit

1148-399: Is covered by forests at present. This is one-third less than the forest cover before the expansion of agriculture, with half of that loss occurring in the last century. Between 15 million to 18 million hectares of forest, an area the size of Bangladesh , are destroyed every year. On average 2,400 trees are cut down each minute. Estimates vary widely as to the extent of deforestation in

1230-421: Is defined as the conversion of forest to other land uses (regardless of whether it is human-induced). Deforestation and forest area net change are not the same: the latter is the sum of all forest losses (deforestation) and all forest gains (forest expansion) in a given period. Net change, therefore, can be positive or negative, depending on whether gains exceed losses, or vice versa. The FAO estimates that

1312-509: Is derived from the Latin word aestuarium meaning tidal inlet of the sea, which in itself is derived from the term aestus , meaning tide. There have been many definitions proposed to describe an estuary. The most widely accepted definition is: "a semi-enclosed coastal body of water, which has a free connection with the open sea, and within which seawater is measurably diluted with freshwater derived from land drainage". However, this definition excludes

1394-605: Is estimated that some 420 million hectares of forest have been lost through conversion to other land uses , although the rate of deforestation has decreased over the past three decades. Between 2015 and 2020, the rate of deforestation was estimated at 10 million hectares per year, down from 16 million hectares per year in the 1990s. The area of primary forest worldwide has decreased by over 80 million hectares since 1990. More than 100 million hectares of forests are adversely affected by forest fires, pests, diseases, invasive species , drought and adverse weather events. Deforestation

1476-411: Is formed, and both riverine and oceanic water flow close to the surface towards this zone. This water is pushed downward and spreads along the bottom in both the seaward and landward direction. Examples of an inverse estuary are Spencer Gulf , South Australia, Saloum River and Casamance River , Senegal. Estuary type varies dramatically depending on freshwater input, and is capable of changing from

1558-560: Is less restricted, and there is a slow but steady exchange of water between the estuary and the ocean. Fjord-type estuaries can be found along the coasts of Alaska , the Puget Sound region of western Washington state , British Columbia , eastern Canada, Greenland , Iceland , New Zealand, and Norway. These estuaries are formed by subsidence or land cut off from the ocean by land movement associated with faulting , volcanoes , and landslides . Inundation from eustatic sea-level rise during

1640-601: Is not an issue because of longer fallow periods and lesser overall deforestation. The relatively small size of the plots allowed for no net input of CO 2 to be released. Consumption and production of beef is the primary driver of deforestation in the Amazon , with around 80% of all converted land being used to rear cattle. 91% of Amazon land deforested since 1970 has been converted to cattle ranching. Livestock ranching requires large portions of land to raise herds of animals and livestock crops for consumer needs. According to

1722-453: Is projected to occur by the mid-21st century. In the early 2000s, some scientists predicted that unless significant measures (such as seeking out and protecting old growth forests that have not been disturbed) are taken on a worldwide basis, by 2030 there will only be 10% remaining, with another 10% in a degraded condition . 80% will have been lost, and with them hundreds of thousands of irreplaceable species. Estimates vary widely as to

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1804-727: Is responsible for 48% of deforestation; commercial agriculture is responsible for 32%; logging is responsible for 14%, and fuel wood removals make up 5%. More than 80% of deforestation was attributed to agriculture in 2018. Forests are being converted to plantations for coffee, tea, palm oil , rice, rubber , and various other popular products. The rising demand for certain products and global trade arrangements causes forest conversions , which ultimately leads to soil erosion . The top soil oftentimes erodes after forests are cleared which leads to sediment increase in rivers and streams. Most deforestation also occurs in tropical regions. The estimated amount of total land mass used by agriculture

1886-461: Is that deforestation reduces the uptake of carbon dioxide ( carbon sequestration ) from the atmosphere. This reduces the potential of forests to assist with climate change mitigation . The role of forests in capturing and storing carbon and mitigating climate change is also important for the agricultural sector. The reason for this linkage is because the effects of climate change on agriculture pose new risks to global food systems . Since 1990, it

1968-543: Is the Colorado River Delta in Mexico, historically covered with marshlands and forests, but now essentially a salt flat. Deforestation Deforestation or forest clearance is the removal and destruction of a forest or stand of trees from land that is then converted to non-forest use. Deforestation can involve conversion of forest land to farms , ranches , or urban use. About 31% of Earth's land surface

2050-639: Is the whitefish species from the European Alps . Eutrophication reduced the oxygen levels in their habitats so greatly that whitefish eggs could not survive, causing local extinctions. However, some animals, such as carnivorous fish, tend to do well in nutrient-enriched environments and can benefit from eutrophication. This can be seen in populations of bass or pikes. Eutrophication can affect many marine habitats which can lead to economic consequences. The commercial fishing industry relies upon estuaries for approximately 68 percent of their catch by value because of

2132-483: Is the world's largest bay. Bays also form through coastal erosion by rivers and glaciers . A bay formed by a glacier is a fjord . Rias are created by rivers and are characterised by more gradual slopes. Deposits of softer rocks erode more rapidly, forming bays, while harder rocks erode less quickly, leaving headlands . Estuary An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with

2214-545: The Congolese rainforest increased by 5%. The World Wildlife Fund 's ecoregion project catalogues habitat types throughout the world, including habitat loss such as deforestation, showing for example that even in the rich forests of parts of Canada such as the Mid-Continental Canadian forests of the prairie provinces half of the forest cover has been lost or altered. In 2011, Conservation International listed

2296-719: The Holocene Epoch has also contributed to the formation of these estuaries. There are only a small number of tectonically produced estuaries; one example is the San Francisco Bay , which was formed by the crustal movements of the San Andreas Fault system causing the inundation of the lower reaches of the Sacramento and San Joaquin rivers . In this type of estuary, river output greatly exceeds marine input and tidal effects have minor importance. Freshwater floats on top of

2378-539: The Mandovi estuary in Goa during the monsoon period. As tidal forcing increases, river output becomes less than the marine input. Here, current induced turbulence causes mixing of the whole water column such that salinity varies more longitudinally rather than vertically, leading to a moderately stratified condition. Examples include the Chesapeake Bay and Narragansett Bay . Tidal mixing forces exceed river output, resulting in

2460-628: The Mid-Atlantic coast, and Galveston Bay and Tampa Bay along the Gulf Coast . Bar-built estuaries are found in a place where the deposition of sediment has kept pace with rising sea levels so that the estuaries are shallow and separated from the sea by sand spits or barrier islands. They are relatively common in tropical and subtropical locations. These estuaries are semi-isolated from ocean waters by barrier beaches ( barrier islands and barrier spits ). Formation of barrier beaches partially encloses

2542-697: The Philippines , Indonesia , Thailand , Burma , Malaysia , Bangladesh , China, Sri Lanka , Laos , Nigeria , the Democratic Republic of the Congo , Liberia , Guinea , Ghana and the Ivory Coast , have lost large areas of their rainforest. Much of what remains of the world's rainforests is in the Amazon basin , where the Amazon Rainforest covers approximately 4 million square kilometres. Some 80% of

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2624-702: The Severn Estuary in the United Kingdom and the Ems Dollard along the Dutch-German border. The width-to-depth ratio of these estuaries is typically large, appearing wedge-shaped (in cross-section) in the inner part and broadening and deepening seaward. Water depths rarely exceed 30 m (100 ft). Examples of this type of estuary in the U.S. are the Hudson River , Chesapeake Bay , and Delaware Bay along

2706-470: The World Wildlife Fund , "Extensive cattle ranching is the number one culprit of deforestation in virtually every Amazon country, and it accounts for 80% of current deforestation." The cattle industry is responsible for a significant amount of methane emissions since 60% of all mammals on earth are livestock cows. Replacing forest land with pastures creates a loss of forest stock , which leads to

2788-478: The black-tailed godwit , rely on estuaries. Two of the main challenges of estuarine life are the variability in salinity and sedimentation . Many species of fish and invertebrates have various methods to control or conform to the shifts in salt concentrations and are termed osmoconformers and osmoregulators . Many animals also burrow to avoid predation and to live in a more stable sedimental environment. However, large numbers of bacteria are found within

2870-577: The tropics . In 2019, nearly a third of the overall tree cover loss, or 3.8 million hectares, occurred within humid tropical primary forests . These are areas of mature rainforest that are especially important for biodiversity and carbon storage . The direct cause of most deforestation is agriculture by far. More than 80% of deforestation was attributed to agriculture in 2018. Forests are being converted to plantations for coffee , palm oil , rubber and various other popular products. Livestock grazing also drives deforestation. Further drivers are

2952-574: The wood industry ( logging ), urbanization and mining . The effects of climate change are another cause via the increased risk of wildfires (see deforestation and climate change ). Deforestation results in habitat destruction which in turn leads to biodiversity loss . Deforestation also leads to extinction of animals and plants, changes to the local climate, and displacement of indigenous people who live in forests. Deforested regions often also suffer from other environmental problems such as desertification and soil erosion . Another problem

3034-497: The Law of the Sea defines a bay as a well-marked indentation in the coastline, whose penetration is in such proportion to the width of its mouth as to contain land-locked waters and constitute more than a mere curvature of the coast. An indentation, however, shall not be regarded as a bay unless its area is as large as (or larger than) that of the semi-circle whose diameter is a line drawn across

3116-400: The United States. Estuaries are incredibly dynamic systems, where temperature, salinity, turbidity, depth and flow all change daily in response to the tides. This dynamism makes estuaries highly productive habitats, but also make it difficult for many species to survive year-round. As a result, estuaries large and small experience strong seasonal variation in their fish communities. In winter,

3198-513: The above definition of an estuary and could be fully saline. Many estuaries suffer degeneration from a variety of factors including soil erosion , deforestation , overgrazing , overfishing and the filling of wetlands. Eutrophication may lead to excessive nutrients from sewage and animal wastes; pollutants including heavy metals , polychlorinated biphenyls , radionuclides and hydrocarbons from sewage inputs; and diking or damming for flood control or water diversion. The word "estuary"

3280-452: The bottom where they are harmless. Historically the oysters filtered the estuary's entire water volume of excess nutrients every three or four days. Today that process takes almost a year, and sediment, nutrients, and algae can cause problems in local waters. Some major rivers that run through deserts historically had vast, expansive estuaries that have been reduced to a fraction of their former size, because of dams and diversions. One example

3362-626: The commodity is consumed. For example, consumption patterns in G7 countries are estimated to cause an average loss of 3.9 trees per person per year. In other words, deforestation can be directly related to imports—for example, coffee. In 2023, the Global Forest Watch reported a 9% decline in tropical primary forest loss compared to the previous year, with significant regional reductions in Brazil and Colombia overshadowed by increases elsewhere, leading to

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3444-469: The country's western regions at a rate of 15,000 hectares at a randomly studied 2-month period in 2010. In 2009, Paraguay's parliament refused to pass a law that would have stopped cutting of natural forests altogether. As of 2007, less than 50% of Haiti's forests remained . From 2015 to 2019, the rate of deforestation in the Democratic Republic of the Congo doubled. In 2021, deforestation of

3526-774: The decades 1990–2000 and 2000–2010. Some claim that rainforests are being destroyed at an ever-quickening pace. The London-based Rainforest Foundation notes that "the UN figure is based on a definition of forest as being an area with as little as 10% actual tree cover, which would therefore include areas that are actually savanna-like ecosystems and badly damaged forests". Other critics of the FAO data point out that they do not distinguish between forest types, and that they are based largely on reporting from forestry departments of individual countries, which do not take into account unofficial activities like illegal logging. Despite these uncertainties, there

3608-498: The deforestation of the Amazon can be attributed to cattle ranching, as Brazil is the largest exporter of beef in the world. The Amazon region has become one of the largest cattle ranching territories in the world. The regions with the highest tropical deforestation rate between 2000 and 2005 were Central America —which lost 1.3% of its forests each year—and tropical Asia. In Central America , two-thirds of lowland tropical forests have been turned into pasture since 1950 and 40% of all

3690-409: The dissolved oxygen from the water; thus hypoxic or anoxic zones can develop. Nitrogen is often the lead cause of eutrophication in estuaries in temperate zones. During a eutrophication event, biogeochemical feedback decreases the amount of available silica . These feedbacks also increase the supply of nitrogen and phosphorus, creating conditions where harmful algal blooms can persist. Given

3772-401: The effects of modifying the estuarine circulation. Fjord -type estuaries are formed in deeply eroded valleys formed by glaciers . These U-shaped estuaries typically have steep sides, rock bottoms, and underwater sills contoured by glacial movement. The estuary is shallowest at its mouth, where terminal glacial moraines or rock bars form sills that restrict water flow. In the upper reaches of

3854-595: The estuary impacted by human activities, and over time may shift the basic composition of the ecosystem, and the reversible or irreversible changes in the abiotic and biotic parts of the systems from the bottom up. For example, Chinese and Russian industrial pollution, such as phenols and heavy metals, has devastated fish stocks in the Amur River and damaged its estuary soil. Estuaries tend to be naturally eutrophic because land runoff discharges nutrients into estuaries. With human activities, land run-off also now includes

3936-424: The estuary, the depth can exceed 300 m (1,000 ft). The width-to-depth ratio is generally small. In estuaries with very shallow sills, tidal oscillations only affect the water down to the depth of the sill, and the waters deeper than that may remain stagnant for a very long time, so there is only an occasional exchange of the deep water of the estuary with the ocean. If the sill depth is deep, water circulation

4018-771: The estuary, with only narrow inlets allowing contact with the ocean waters. Bar-built estuaries typically develop on gently sloping plains located along tectonically stable edges of continents and marginal sea coasts. They are extensive along the Atlantic and Gulf coasts of the U.S. in areas with active coastal deposition of sediments and where tidal ranges are less than 4 m (13 ft). The barrier beaches that enclose bar-built estuaries have been developed in several ways: Fjords were formed where Pleistocene glaciers deepened and widened existing river valleys so that they become U-shaped in cross-sections. At their mouths there are typically rocks, bars or sills of glacial deposits , which have

4100-463: The extent of deforestation in the tropics. In 2019, the world lost nearly 12 million hectares of tree cover. Nearly a third of that loss, 3.8 million hectares, occurred within humid tropical primary forests, areas of mature rainforest that are especially important for biodiversity and carbon storage. This is equivalent to losing an area of primary forest the size of a football pitch every six seconds. A 2002 analysis of satellite imagery suggested that

4182-609: The fish community is dominated by hardy marine residents, and in summer a variety of marine and anadromous fishes move into and out of estuaries, capitalizing on their high productivity. Estuaries provide a critical habitat to a variety of species that rely on estuaries for life-cycle completion. Pacific Herring ( Clupea pallasii ) are known to lay their eggs in estuaries and bays, surfperch give birth in estuaries, juvenile flatfish and rockfish migrate to estuaries to rear, and anadromous salmonids and lampreys use estuaries as migration corridors. Also, migratory bird populations, such as

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4264-432: The form of charcoal or timber ), while cleared land is used as pasture for livestock and agricultural crops. The vast majority of agricultural activity resulting in deforestation is subsidized by government tax revenue . Disregard of ascribed value, lax forest management , and deficient environmental laws are some of the factors that lead to large-scale deforestation. The types of drivers vary greatly depending on

4346-568: The global forest carbon stock has decreased 0.9%, and tree cover 4.2% between 1990 and 2020. As of 2019 there is still disagreement about whether the global forest is shrinking or not: "While above-ground biomass carbon stocks are estimated to be declining in the tropics, they are increasing globally due to increasing stocks in temperate and boreal forest. Deforestation in many countries —both naturally occurring and human-induced —is an ongoing issue. Between 2000 and 2012, 2.3 million square kilometres (890,000 square miles) of forests around

4428-400: The great biodiversity of this ecosystem. During an algal bloom , fishermen have noticed a significant increase in the quantity of fish. A sudden increase in primary productivity causes spikes in fish populations which leads to more oxygen being utilized. It is the continued deoxygenation of the water that then causes a decline in fish populations. These effects can begin in estuaries and have

4510-420: The impacts do not end there. Plant death alters the entire food web structure which can result in the death of animals within the afflicted biome . Estuaries are hotspots for biodiversity , containing a majority of commercial fish catch, making the impacts of eutrophication that much greater within estuaries. Some specific estuarine animals feel the effects of eutrophication more strongly than others. One example

4592-402: The implication of increased greenhouse gas emissions by burning agriculture methodologies and land-use change . A large contributing factor to deforestation is the lumber industry . A total of almost 4 million hectares (9.9 million acres) of timber, or about 1.3% of all forest land, is harvested each year. In addition, the increasing demand for low-cost timber products only supports

4674-691: The largest annual rate of net forest loss in 2010–2020, at 3.9 million ha, followed by South America, at 2.6 million ha. The rate of net forest loss has increased in Africa in each of the three decades since 1990. It has declined substantially in South America, however, to about half the rate in 2010–2020 compared with 2000–2010. Asia had the highest net gain of forest area in 2010–2020, followed by Oceania and Europe. Nevertheless, both Europe and Asia recorded substantially lower rates of net gain in 2010–2020 than in 2000–2010. Oceania experienced net losses of forest area in

4756-430: The main driver of deforestation and forest fragmentation and the associated loss of forest biodiversity. Large-scale commercial agriculture (primarily cattle ranching and cultivation of soya bean and oil palm) accounted for 40 percent of tropical deforestation between 2000 and 2010, and local subsistence agriculture for another 33 percent. Trees are cut down for use as building material, timber or sold as fuel (sometimes in

4838-525: The many chemicals used as fertilizers in agriculture as well as waste from livestock and humans. Excess oxygen-depleting chemicals in the water can lead to hypoxia and the creation of dead zones . This can result in reductions in water quality, fish, and other animal populations. Overfishing also occurs. Chesapeake Bay once had a flourishing oyster population that has been almost wiped out by overfishing. Oysters filter these pollutants, and either eat them or shape them into small packets that are deposited on

4920-422: The marine environment, such as plastics , pesticides , furans , dioxins , phenols and heavy metals . Such toxins can accumulate in the tissues of many species of aquatic life in a process called bioaccumulation . They also accumulate in benthic environments, such as estuaries and bay muds : a geological record of human activities of the last century. The elemental composition of biofilm reflect areas of

5002-575: The marsh causing increased rates of erosion . A similar phenomenon occurs in mangrove swamps , which are another potential ecosystem in estuaries. An increase in nitrogen causes an increase in shoot growth and a decrease in root growth. Weaker root systems cause a mangrove tree to be less resilient in seasons of drought, which can lead to the death of the mangrove. This shift in above ground and below ground biomass caused by eutrophication could hindered plant success in these ecosystems. Across all biomes, eutrophication often results in plant death but

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5084-451: The mouth of that indentation — otherwise it would be referred to as a bight . There are various ways in which bays can form. The largest bays have developed through plate tectonics . As the super-continent Pangaea broke up along curved and indented fault lines, the continents moved apart and left large bays; these include the Gulf of Guinea , the Gulf of Mexico , and the Bay of Bengal , which

5166-440: The now off-balance nitrogen cycle , estuaries can be driven to phosphorus limitation instead of nitrogen limitation. Estuaries can be severely impacted by an unbalanced phosphorus cycle, as phosphorus interacts with nitrogen and silica availability. With an abundance of nutrients in the ecosystem, plants and algae overgrow and eventually decompose, which produce a significant amount of carbon dioxide. While releasing CO 2 into

5248-460: The nutrients in the ashes of the burned plants. As well as, intentionally set fires can possibly lead to devastating measures when unintentionally spreading fire to more land, which can result in the destruction of the protective canopy. The repeated cycle of low yields and shortened fallow periods eventually results in less vegetation being able to grow on once burned lands and a decrease in average soil biomass. In small local plots sustainability

5330-548: The original 16 million square kilometres (6 million square miles) of tropical rainforest that formerly covered the Earth. More than 3.6 million hectares of virgin tropical forest was lost in 2018. The global annual net loss of trees is estimated to be approximately 10 billion. According to the Global Forest Resources Assessment 2020 the global average annual deforested land in the 2015–2020 demi-decade

5412-418: The other hand, a 2005 analysis of satellite images reveals that deforestation of the Amazon rainforest is twice as fast as scientists previously estimated. From 2010 to 2015, worldwide forest area decreased by 3.3 million ha per year, according to FAO . During this five-year period, the biggest forest area loss occurred in the tropics, particularly in South America and Africa. Per capita forest area decline

5494-410: The planet had 15 to 16 million km (5.8 to 6.2 million sq mi) of mature tropical forests , but by 2015, it was estimated that about half of these had been destroyed. Total land coverage by tropical rainforests decreased from 14% to 6%. Much of this loss happened between 1960 and 1990, when 20% of all tropical rainforests were destroyed. At this rate, extinction of such forests

5576-488: The rainforests have been lost in the last 40 years. Brazil has lost 90–95% of its Mata Atlântica forest. Deforestation in Brazil increased by 88% for the month of June 2019, as compared with the previous year. However, Brazil still destroyed 1.3 million hectares in 2019. Brazil is one of several countries that have declared their deforestation a national emergency. Paraguay was losing its natural semi-humid forests in

5658-463: The rate of deforestation in the humid tropics (approximately 5.8 million hectares per year) was roughly 23% lower than the most commonly quoted rates. A 2005 report by the United Nations Food and Agriculture Organization (FAO) estimated that although the Earth's total forest area continued to decrease at about 13 million hectares per year, the global rate of deforestation had been slowing. On

5740-469: The region in which they take place. The regions with the greatest amount of deforestation for livestock and row crop agriculture are Central and South America, while commodity crop deforestation was found mainly in Southeast Asia. The region with the greatest forest loss due to shifting agriculture was sub-Saharan Africa. The overwhelming direct cause of deforestation is agriculture. Subsistence farming

5822-427: The seawater in a layer that gradually thins as it moves seaward. The denser seawater moves landward along the bottom of the estuary, forming a wedge-shaped layer that is thinner as it approaches land. As a velocity difference develops between the two layers, shear forces generate internal waves at the interface, mixing the seawater upward with the freshwater. An examples of a salt wedge estuary is Mississippi River and

5904-411: The sediment which has a very high oxygen demand. This reduces the levels of oxygen within the sediment often resulting in partially anoxic conditions, which can be further exacerbated by limited water flow. Phytoplankton are key primary producers in estuaries. They move with the water bodies and can be flushed in and out with the tides . Their productivity is largely dependent upon the turbidity of

5986-513: The size of India—by 2050. 36% of globally planted forest area is in East Asia – around 950,000 square kilometers. From those 87% are in China. Rates of deforestation vary around the world. Up to 90% of West Africa 's coastal rainforests have disappeared since 1900. Madagascar has lost 90% of its eastern rainforests. In South Asia , about 88% of the rainforests have been lost. Mexico , India ,

6068-467: The top 10 most endangered forests, characterized by having all lost 90% or more of their original habitat , and each harboring at least 1500 endemic plant species (species found nowhere else in the world). As of 2015 , it is estimated that 70% of the world's forests are within one kilometer of a forest edge, where they are most prone to human interference and destruction. Deforestation in particular countries: Agricultural expansion continues to be

6150-456: The volume of freshwater, the tidal range, and the extent of evaporation of the water in the estuary. Drowned river valleys are also known as coastal plain estuaries. In places where the sea level is rising relative to the land, sea water progressively penetrates into river valleys and the topography of the estuary remains similar to that of a river valley. This is the most common type of estuary in temperate climates. Well-studied estuaries include

6232-453: The water and atmosphere, these organisms are also intaking all or nearly all of the available oxygen creating a hypoxic environment and unbalanced oxygen cycle . The excess carbon in the form of CO 2 can lead to low pH levels and ocean acidification , which is more harmful for vulnerable coastal regions like estuaries. Eutrophication has been seen to negatively impact many plant communities in estuarine ecosystems . Salt marshes are

6314-619: The water column and in sediment , making estuaries among the most productive natural habitats in the world. Most existing estuaries formed during the Holocene epoch with the flooding of river-eroded or glacially scoured valleys when the sea level began to rise about 10,000–12,000 years ago. Estuaries are typically classified according to their geomorphological features or to water-circulation patterns. They can have many different names, such as bays , harbors , lagoons , inlets , or sounds , although some of these water bodies do not strictly meet

6396-835: The water. The main phytoplankton present are diatoms and dinoflagellates which are abundant in the sediment. A primary source of food for many organisms on estuaries, including bacteria , is detritus from the settlement of the sedimentation. Of the thirty-two largest cities in the world in the early 1990s, twenty-two were located on estuaries. As ecosystems, estuaries are under threat from human activities such as pollution and overfishing . They are also threatened by sewage, coastal settlement, land clearance and much more. Estuaries are affected by events far upstream, and concentrate materials such as pollutants and sediments. Land run-off and industrial, agricultural, and domestic waste enter rivers and are discharged into estuaries. Contaminants can be introduced which do not disintegrate rapidly in

6478-473: The world were cut down. Deforestation and forest degradation continue to take place at alarming rates, which contributes significantly to the ongoing loss of biodiversity . Deforestation is more extreme in tropical and subtropical forests in emerging economies. More than half of all plant and land animal species in the world live in tropical forests . As a result of deforestation, only 6.2 million square kilometres (2.4 million square miles) remain of

6560-564: The world, especially in East Asian countries, reforestation and afforestation are increasing the area of forested lands. The amount of forest has increased in 22 of the world's 50 most forested nations. Asia as a whole gained 1 million hectares of forest between 2000 and 2005. Tropical forest in El Salvador expanded more than 20% between 1992 and 2001. Based on these trends, one study projects that global forestation will increase by 10%—an area

6642-456: Was 10 million hectares and the average annual forest area net loss in the 2000–2010 decade was 4.7 million hectares. The world has lost 178 million ha of forest since 1990, which is an area about the size of Libya. An analysis of global deforestation patterns in 2021 showed that patterns of trade, production, and consumption drive deforestation rates in complex ways. While the location of deforestation can be mapped, it does not always match where

6724-461: Was also greatest in the tropics and subtropics but is occurring in every climatic domain (except in the temperate) as populations increase. An estimated 420 million ha of forest has been lost worldwide through deforestation since 1990, but the rate of forest loss has declined substantially. In the most recent five-year period (2015–2020), the annual rate of deforestation was estimated at 10 million ha, down from 12 million ha in 2010–2015. Africa had

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