what is the cause of most of the threats to biodiversity

Habitat Loss and Sustainability

Through increased adoption of sustainable practices, we can reduce habitat loss and its consequences.

Learning Objectives

Describe the effects of habitat loss to biodiversity and concept of sustainability

Key Takeaways

Central Points

• Habitat destruction renders entire habitats functionally unable to support the species present; biodiversity is reduced in this procedure when existing organisms in the habitat are displaced or destroyed.
• Clearing areas for agricultural purposes is the main crusade of habitat destruction; other principal causes include mining, logging, and urban sprawl.
• The chief crusade of species extinction worldwide is habitat destruction.
• Sustainability is a term that describes how biological systems remain diverse and productive over time, creating the potential for long-term maintenance of human well-existence.
• Reducing negative human being impact requires 3 concepts: ecology direction, management of human consumption of resources, and awareness of cultural and political concerns to increase sustainability.

Key Terms

• sustainability: Configuring society so that each person can run into their own needs and greatest potential, while preserving biodiversity and natural ecosystems, and planning for hereafter generations to maintain this potential.
• endemism: The ecological state of a species being unique to a defined geographic location, such as an island, nation, state or other defined zone, or habitat type; organisms that are indigenous to a identify are not owned to it if they are also found elsewhere.
• biodiversity: The diverseness (number and variety of species) of constitute and animal life within a region.

Habitat Loss

Humans rely on applied science to modify their environment and replace certain functions that were once performed by the natural ecosystem. Other species cannot practise this. Elimination of their ecosystem – whether it is a woods, a desert, a grassland, a freshwater estuary, or a marine environs – will kill the individuals within most species. Remove the unabridged habitat within the range of a species and, unless they are ane of the few species that do well in human-congenital environments, the species volition get extinct.

Effects of Habitat Loss on Biodiversity

Habitat loss is a procedure of environmental change in which a natural habitat is rendered functionally unable to support the species present. This process may be natural or unnatural, and may be caused by habitat fragmentation, geological processes, climate alter, or human activities such every bit the introduction of invasive species or ecosystem nutrient depletion. In the procedure of habitat destruction, the organisms that previously used the site are displaced or destroyed, reducing biodiversity.

Biodiversity loss in Sumatra: (a) One sub-species of orangutan is found only in the pelting forests of Kalimantan, while the other sub-species of orangutan is found but in the rain forests of Sumatra. These animals are examples of the infrequent biodiversity of (c) the islands of Sumatra and Borneo. Other species include the (b) Sumatran tiger and the (d) Sumatran elephant, both of which are critically endangered. Rainforest habitat is beingness removed to make fashion for (e) oil palm plantations such every bit this i in Kalimantan'southward Sabah Province.

Human devastation of habitats has accelerated greatly in the latter half of the twentieth century. Natural habitats are often destroyed through human activity for the purpose of harvesting natural resources for industry production and urbanization. Clearing habitats for agriculture, for instance, is the main cause of habitat destruction. Other important causes of habitat devastation include mining, logging, and urban sprawl. Habitat devastation is currently ranked every bit the primary cause of species extinction worldwide.

Consider the infrequent biodiversity of Sumatra. It is dwelling to ane sub-species of orangutan, a species of critically endangered elephant, and the Sumatran tiger; however one-half of Sumatra's wood is now gone. The neighboring isle of Borneo, home to the other sub-species of orangutan, has lost a similar area of forest, and woods loss continues in protected areas. The orangutan in Borneo is listed as endangered by the International Spousal relationship for Conservation of Nature (IUCN), simply it is simply the virtually visible of thousands of species that will not survive the disappearance of the forests of Kalimantan. The forests are being removed for their timber, and to clear space for plantations of palm oil, an oil used in Europe for many items including food products, cosmetics, and biodiesel.

A five-year judge of global forest encompass loss for the years 2000–2005 was 3.1 pct. In the humid torrid zone where forest loss is primarily from timber extraction, 272,000 km^two was lost out of a global total of eleven,564,000 kmⁱⁱ (or 2.four percent). In the torrid zone, these losses also represent the extinction of species because of high levels of endemism.

Since the Neolithic Revolution, about 47% of the earth's forests have been lost to human being employ. Present-solar day forests occupy about a quarter of the world's ice-free state, with about half of these occurring in the tropics. In temperate and boreal regions, forest area is gradually increasing (with the exception of Siberia), but deforestation in the tropics is of major concern.

Feeding more than than seven billion human bodies takes a heavy toll on the earth's resources. This begins with the cribbing of about 38 pct of the earth'south state surface and near 20 percent of its net primary productivity. Added to this are the resource-hungry activities of industrial agribusiness: everything from crops' need for irrigation water, constructed fertilizers, and pesticides, to the resource costs of food packaging, send (now a major part of global merchandise), and retail.

Sustainability and deforestation: Since the Neolithic Revolution, nearly half of the world's forests have been destroyed for homo use. Sustainable practices, which preserve environments for long-term maintenance and well-being, can assist preserve habitats and ecosystems for greater biodiversity.

Sustainability

Sustainability is a concept that describes how biological systems remain various and productive over time. Long-lived and healthy wetlands and forests are examples of sustainable biological systems. For humans, sustainability is the potential for long-term maintenance of well-being, which has ecological, economic, political, and cultural dimensions. Sustainability requires the reconciliation of ecology, social, and economic demands, which are also referred to equally the "three pillars" of sustainability.

Salubrious ecosystems and environments are necessary for the survival and flourishing of humans and other organisms, and at that place are a number of ways to reduce humans' negative touch on the environment. One approach is environmental management, which is based largely on information gained from earth science, environmental science, and conservation biology. A 2d approach is management of human consumption of resources, which is based largely on information gained from economics. A 3rd, more recent, approach adds cultural and political concerns into the sustainability matrix.

Loss of biodiversity stems largely from the habitat loss and fragmentation produced by human appropriation of country for development, forestry and agriculture equally natural capital is progressively converted to human being-made capital. At the local man scale, sustainability benefits accumulate from the creation of green cities and sustainable parks and gardens. Similarly, environmental problems associated with industrial agriculture and agribusiness are now beingness addressed through such movements equally sustainable agronomics, organic farming, and more than-sustainable business organisation practices.

Overharvesting

Overharvesting threatens biodiversity past degrading ecosystems and eliminating species of plants, animals, and other organisms.

Learning Objectives

Explain why overharvesting is a threat to biodiversity

Cardinal Takeaways

Key Points

• Until recently, human being populations harvested resource in limited quantities. Today, new methods of harvest and capture contribute to overharvesting and overexploitation.
• Overharvesting stems from several factors, including an exponential increment in the human population, expanding markets, increasing demand, and improved admission and techniques for capture.
• Overharvesting natural resource for extended periods of time depletes these resources until they cannot recover within a short period of time; some may never recover.
• Overharvesting is 1 of five primary activities threatening global biodiversity; others include pollution, introduced species, habitat fragmentation, and habitat destruction.
• Aquatic species are especially threatened by overharvesting, due to a situation known equally the tragedy of the eatables.

Primal Terms

• overexploitation: Excessive and damaging apply of natural resource, including plants and animals.
• trawler: A fishing boat that uses a dragnet, or "trawl internet," to catch fish.
• apex predator: An animal at the height of the nutrient chain, preying on other species but non casualty itself.

Overharvesting

Overharvesting, too called overexploitation, refers to harvesting a renewable resource to the point of diminishing returns. Ecologists use the term to draw populations that are harvested at a rate that is unsustainable, given their natural rates of mortality and capacities for reproduction. The term applies to natural resources such as wild medicinal plants, grazing pastures, game animals, fish stocks, forests, and water aquifers. Sustained overharvesting can lead to the destruction of the resource, and is one of the five main activities – along with pollution, introduced species, habitat fragmentation, and habitat destruction – that threaten global biodiversity today.

All living organisms require resources to survive. Overharvesting these resources for extended periods of time can deplete natural resources to the bespeak where they are unable to recover within a short time frame. Humans accept always harvested food and other resources they have needed to survive; still, human populations, historically, were small and methods of collection express to minor quantities. Exponential increase in human being population, expanding markets, and increasing demand, combined with improved admission and techniques for capture, are causing the exploitation of many species beyond sustainable levels.

Furnishings of overharvesting

As mentioned above, sustained overharvesting is one of the primary threats to biodiversity. Overharvesting can lead to resource destruction, including extinction at the population level and even extinction of whole species. Depleting the numbers or corporeality of certain resource can as well alter their quality; for instance, the overharvesting of footstool palm (a wild palm tree institute in Southeast Asia, the leaves of which are used for thatching and food wrapping) has resulted in its leaf size becoming smaller.

Overharvesting not only threatens the resource existence harvested, but tin directly touch humans as well – for example by decreasing the biodiversity necessary for medicinal resource. A significant proportion of drugs and medicines are natural products which are derived, directly or indirectly, from biological sources. However, unregulated and inappropriate harvesting could potentially lead to overexploitation, ecosystem degradation, and loss of biodiversity; further, it can negatively impact the rights of the communities and states from which the resources are taken.

Tragedy of the commons

Overharvesting is a serious threat to many species, especially aquatic ones. Common resources – or resources that are shared, such equally fisheries – are subject to an economic pressure known as "the tragedy of the eatables," in which essentially no harvester has a motivation to exercise restraint in harvesting from a certain area, because that area is non owned by that harvester. The natural effect of harvesting mutual resources is their overexploitation.

For example, most fisheries are managed equally a common resource fifty-fifty when the fishing territory lies within a state's territorial waters; because of this, fishers have very trivial motivation to limit their harvesting, and in fact technology gives fishers the ability to overfish. In a few fisheries, the biological growth of the resource is less than the potential growth of the profits made from fishing if that fourth dimension and coin were invested elsewhere. In these cases (for example, whales) economic forces will always bulldoze toward angling the population to extinction.

Cod trawler and net: Overharvesting fisheries is an specially salient problem because of a situation termed the tragedy of the eatables. In this situation, fishers have no real incentive to practice restraint when harvesting fish because they exercise not own the fisheries.

Cascade Effects

Overexploitation of species can also result in cascade effects, particularly if a habitat loses its apex predator. Because of the loss of the top predator, a dramatic increase in their prey species tin can occur. In turn, the unchecked casualty can then overexploit their own food resource until population numbers dwindle, possibly to the betoken of extinction.

Exotic Species

Exotic species introduced into foreign ecosystems can threaten native species through competition for resources, predation, and disease.

Learning Objectives

Draw the impact of exotic and invasive species on native species

Key Takeaways

Key Points

• Exotic species introduced to new environments often reset the ecological atmospheric condition in that new habitat, threatening the species that be there; this is the reason that they are also termed invasive species.
• Invasive species that are closely related to rare native species take the potential to hybridize with the native species; harmful furnishings of hybridization accept led to a decline and even extinction of native species.
• Biologists studying frogs and toads may be inadvertently responsible for the worldwide spread of a fungus deadly to amphibians.

Key Terms

• invasive species: any species that has been introduced to an surround where information technology is not native and has since become a nuisance through rapid spread and increment in numbers, ofttimes to the detriment of native species

Exotic Species

Exotic species are those that have been intentionally or unintentionally introduced past humans into an ecosystem in which they did not evolve. Such introductions probably occur frequently equally natural phenomena. For example, Kudzu (Pueraria lobata), which is native to Nihon, was introduced in the United States in 1876. Information technology was later planted for soil conservation. Problematically, information technology grows too well in the southeastern United States: upward to one foot each day. Information technology is now a pest species, covering over 7 million acres in the southeastern United States. If an introduced species is able to survive in its new habitat, that introduction is now reflected in the observed range of the species. Human transportation of people and goods, including the intentional transport of organisms for trade, has dramatically increased the introduction of species into new ecosystems, sometimes at distances that are well beyond the capacity of the species to ever travel itself and outside the range of the species' natural predators.

Exotic threats: The brown tree serpent, Boiga irregularis, is an exotic species that has caused numerous extinctions on the island of Guam since its adventitious introduction in 1950.

Most exotic species introductions probably fail because of the low number of individuals introduced or poor adaptation to the ecosystem they enter. Some species, notwithstanding, possess preadaptations that tin make them especially successful in a new ecosystem. These exotic species frequently undergo dramatic population increases in their new habitat, resetting the ecological weather in the new surround, while threatening the species that exist there. For this reason, exotic species, also called invasive species, tin threaten other species through competition for resource, predation, or disease.

Exotic Species Threaten Native Species

Invasive species tin can alter the functions of ecosystems. For example, invasive plants tin can alter the fire regimen, food cycling, and hydrology in native ecosystems. Invasive species that are closely related to rare native species accept the potential to hybridize with the native species. Harmful effects of hybridization have led to a decline and fifty-fifty extinction of native species. For case, hybridization with introduced cordgrass, Spartina alterniflora, threatens the existence of California cordgrass in San Francisco Bay. Invasive species crusade competition for native species. Four hundred of the 958 endangered species nether the Endangered Species Act are at risk due to this competition.

Global decline in amphibian species: This Limosa Harlequin Frog (Atelopus limosus), an endangered species from Panama, died from a fungal disease called chytridiomycosis. The cherry-red lesions are symptomatic of the affliction.

Lakes and islands are peculiarly vulnerable to extinction threats from introduced species. In Lake Victoria, as mentioned earlier, the intentional introduction of the Nile perch was largely responsible for the extinction of about 200 species of cichlids. The adventitious introduction of the brown tree snake via aircraft from the Solomon Islands to Guam in 1950 has led to the extinction of three species of birds and iii to 5 species of reptiles endemic to the island. Several other species are still threatened. The dark-brown tree serpent is skilful at exploiting homo transportation as a means to drift; one was fifty-fifty found on an aircraft arriving in Corpus Christi, Texas. Constant vigilance on the part of airport, military, and commercial aircraft personnel is required to prevent the serpent from moving from Guam to other islands in the Pacific, especially Hawaii. Islands do not make upwards a large expanse of land on the globe, but they do contain a disproportionate number of endemic species considering of their isolation from mainland ancestors.

It at present appears that the global decline in amphibian species recognized in the 1990s is, in some function, caused by the fungus Batrachochytrium dendrobatidis, which causes the disease chytridiomycosis. There is evidence that the fungus, native to Africa, may have been spread throughout the globe by transport of a commonly-used laboratory and pet species: the African clawed toad (Xenopus laevis). It may well be that biologists themselves are responsible for spreading this disease worldwide. The North American bullfrog, Rana catesbeiana, which has likewise been widely introduced as a nutrient animal, but which hands escapes captivity, survives most infections of Batrachochytriumdendrobatidis and can deed as a reservoir for the disease.

Climate Change and Biodiversity

The global warming trend is recognized as a major biodiversity threat, particularly when combined with other threats such as habitat loss.

Learning Objectives

Evaluate climate change and its impact on biodiversity

Primal Takeaways

Cardinal Points

• This warming trend is persistently shifting colder climates further toward the north and south poles, forcing species to movement with their own adjusted climate norms, while as well facing habitat gaps forth the manner.
• Climate shifts will motility up mountains, resulting in the crowding of species higher in altitude and eliminating the habitat for those species adapted to those high elevations; indeed, some climates will completely disappear.
• Global warming will also raise sea water levels due to melted h2o from glaciers and the greater volume of warmer water; shorelines will be flooded, affecting many species; many islands will disappear altogether.

Cardinal Terms

• anthropogenic: having its origin in the influence of human activeness on nature
• biodiversity: the diversity (number and multifariousness of species) of establish and animal life within a region

Climate Modify

Climatic change, specifically, the anthropogenic (acquired by humans) warming tendency soon underway, is recognized equally a major extinction threat, particularly when combined with other threats such as habitat loss. Scientists disagree about the probable magnitude of the effects, with extinction rate estimates ranging from fifteen percent to xl percent of species by 2050. Scientists practice hold, however, that climate change will alter regional climates, including rainfall and snow patterns, making habitats less hospitable to the species living in them.

Impact of Climatic change on Biodiversity

Grizzly-polar comport hybrid: Since 2008, grizzly bears (Ursus arctos horribilis) have been spotted further north than their celebrated range, a possible consequence of climatic change. Equally a event, grizzly deport habitat now overlaps polar bear (Ursus maritimus) habitat. The ii kinds of bears, which are capable of mating and producing viable offspring, are considered divide species as historically they lived in different habitats and never met. However, in 2006 a hunter shot a wild grizzly-polar acquit hybrid known as a grolar bear, the first wild hybrid e'er constitute.

The warming trend will shift colder climates toward the northward and southward poles, forcing species to move with their adjusted climate norms while facing habitat gaps along the fashion. The shifting ranges will impose new competitive regimes on species as they find themselves in contact with other species not present in their historic range. One such unexpected species contact is between polar bears and grizzly bears. Previously, these two species had separate ranges. At present, with their ranges are overlapping, in that location are documented cases of these 2 species mating and producing viable offspring. Changing climates also throw off species' delicate timing adaptations to seasonal food resources and convenance times. Many gimmicky mismatches to shifts in resources availability and timing have recently been documented.

Range shifts are already being observed. For example, some European bird species' ranges have moved 91 km northward. The same study suggests that the optimal shift based on warming trends was double that distance, suggesting that the populations are non moving quickly enough. Range shifts accept besides been observed in plants, butterflies, other insects, freshwater fishes, reptiles, and mammals.

Climate gradients will too move up mountains, eventually crowding species higher in distance and eliminating the habitat for those species adapted to the highest elevations. Some climates volition completely disappear. The rate of warming appears to exist accelerated in the arctic, which is recognized as a serious threat to polar acquit populations that crave sea ice to hunt seals during the winter months; seals are the only source of protein available to polar bears. A trend to decreasing sea ice coverage has occurred since observations began in the mid-twentieth century. The charge per unit of decline observed in recent years is far greater than previously predicted by climate models.

Finally, global warming will raise ocean levels due to glacial melt and the greater volume of warmer h2o. Shorelines will be inundated, reducing island size, which volition have an effect on many species; a number of islands will disappear entirely. Additionally, the gradual melting and subsequent refreezing of the poles, glaciers, and higher meridian mountains, a cycle that has provided freshwater to environments for centuries, will also exist jeopardized. This could result in an glut of table salt water and a shortage of fresh water.

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Source: https://courses.lumenlearning.com/boundless-biology/chapter/threats-to-biodiversity/

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