Overexploitation
Encyclopedia
Overexploitation, also called overharvesting, refers to harvesting a renewable resource to the point of diminishing returns. Sustained overexploitation can lead to the destruction of the resource. The term applies to natural resource
s such as: wild medicinal plants, grazing pasture
s, fish stocks, forests and water aquifers
.
In ecology
, overexploitation describes one of the five main activities threatening global biodiversity
. Ecologists use the term to describe populations that are harvested at a rate that is unsustainable, given their natural rates of mortality and capacities for reproduction. This can result in extinction at the population level and even extinction of whole species. In conservation biology
the term is usually used in the context of human economic activity that involves the taking of biological resources, or organisms, in larger numbers than their populations can withstand. The term is also used and defined somewhat differently in fisheries, hydrology
and natural resource management
.
Overexploitation can lead to resource destruction, including extinction
s. However it is also possible for overexploitation to be sustainable, as discussed below in the section on fisheries. In the context of fishing, the term overfishing
can be used instead of overexploitation, as can overgrazing
in stock management
, overlogging in forest management
, overdrafting
in aquifer management, and endangered species
in species monitoring. Overexploitation is not an activity limited to humans. Introduced predators and herbivores, for example, can overexploit native flora
and fauna
.
Concern about overexploitation is relatively recent, though overexploitation itself is not a new phenomenon. It has been observed for millennia. For example, ceremonial cloaks worn by the Hawaiian kings were made from the mamo
bird; a single cloak used the feathers of 70,000 birds of this now-extinct species. The dodo
, a flightless bird from Mauritius
, is another well known example of overexploitation. As with many island species, it was naive about certain predators, allowing humans to approach and kill it with ease.
From the earliest of times, hunting
for wild mammal
s and bird
s has been an important human activity as a means of survival. There is a whole history of overexploitation in the form of overhunting. The overkill hypothesis (Quaternary extinction event
s) explains why the megafauna
l extinctions occurred within a relatively short period of time. This can be traced with human migration
. The most convincing evidence of this theory is that 80% of the North American large mammal species disappeared within 1000 years of the arrival of humans on the western hemisphere continents. Again, in New Zealand
, ten species of the giant moa birds
were hunted to extinction by the Māori by 1500 AD. A second wave of extinctions occurred later with European settlement.
In more recent times, overexploitation has resulted in the gradual emergence of the concepts of sustainability
and sustainable development
, which has built on other concepts, such as sustainable yield
, eco-development and deep ecology
.
is a wild palm tree found in Southeast Asia. Its leaves are used for thatching and food wrapping, and overharvesting has resulted in its leaf size becoming smaller.
refers to a dilemma described in an article by that name written by Garrett Hardin
and first published in the journal Science
in 1968.
Central to Hardin's essay is an example which is a useful parable for understanding how overexploitation can occur. This example was first sketched in an 1833 pamphlet by William Forster Lloyd
, as a hypothetical and simplified situation based on medieval land tenure
in Europe, of herders sharing a common
on which they are each entitled to let their cows graze. In Hardin's example, it is in each herder's interest to put each succeeding cow he acquires onto the land, even if the carrying capacity
of the common is exceeded and it is temporarily or permanently damaged for all as a result. The herder receives all of the benefits from an additional cow, while the damage to the common is shared by the entire group. If all herders make this individually rational economic decision, the common will be overexploited or even destroyed to the detriment of all. However, since all herders reach the same rational conclusion, overexploitation in the form of overgrazing
occurs, with immediate losses, and the pasture may be degraded to the point where it gives very little return.
In the course of his essay, Hardin develops the theme, drawing in many examples of latter day commons, such as national park
s, the atmosphere, oceans, rivers and fish stocks. The example of fish stocks had led some to call this the "tragedy of the fishers". A major theme running through the essay is the growth of human populations, with the Earth
's finite resources being the general common.
The tragedy of the commons has intellectual roots tracing back to Aristotle
, who noted that "what is common to the greatest number has the least care bestowed upon it", as well as to Hobbes and his leviathan
. The opposite situation to a tragedy of the commons is sometimes referred to as a tragedy of the anticommons
: a situation in which rational individuals, acting separately, collectively waste a given resource by underutilizing it.
The tragedy of the commons can be avoided if it is appropriately regulated. Hardin's use of "commons" has frequently been misunderstood, leading Hardin to later remark that he should have titled his work "The tragedy of the unregulated commons".
In wild fisheries, overexploitation or overfishing
occurs when a fish stock
has been fished down "below the size that, on average, would support the long-term maximum sustainable yield
of the fishery". However, overexploitation can be sustainable.
When a fishery starts harvesting fish from a previously unexploited stock, the biomass
of the fish stock will decrease, since harvesting means fish are being removed. For sustainability, the rate at which the fish replenish biomass through reproduction must balance the rate at which the fish are being harvested. If the harvest rate is increased, then the stock biomass will further decrease. At a certain point, the maximum harvest yield that can be sustained will be reached, and further attempts to increase the harvest rate will result in the collapse of the fishery. This point is called the maximum sustainable yield
, and in practice, usually occurs when the fishery has been fished down to about 30% of the biomass it had before harvesting started.
It is possible to fish the stock down further to, say, 15% of the pre-harvest biomass, and then adjust the harvest rate so the biomass remains at that level. In this case, the fishery is sustainable, but is now overexploited, because the stock has been run down to the point where the sustainable yield is less than it could be.
Fish stocks are said to "collapse" if their biomass declines by more than 95 percent of their maximum historical biomass. Atlantic cod
stocks were severely overexploited in the 1970s and 1980s, leading to their abrupt collapse in 1992. Even though fishing has ceased, the cod stocks have failed to recover. The absence of cod as the apex predator
in many areas has led to trophic cascade
s.
About 25% of world fisheries are now overexploited to the point where their current biomass is less than the level that maximizes their sustainable yield. These depleted fisheries can often recover if fishing pressure is reduced until the stock biomass returns to the optimal biomass. At this point, harvesting can be resumed near the maximum sustainable yield.
The tragedy of the commons
can be avoided within the context of fisheries if fishing effort and practices are regulated appropriately by fisheries management
. One effective approach may be assigning some measure of ownership in the form of individual transferable quotas (ITQs) to fishermen. In 2008, a large scale study of fisheries that used ITQs, and ones that didn't, provided strong evidence that ITQs help prevent collapses and restore fisheries that appear to be in decline.
Water resource, such as lake
s and aquifer
s, are usually renewable resources which naturally recharge (the term fossil water
is sometimes used to describe aquifers which don't recharge). Overexploitation occurs if a water resource, such as the Ogallala Aquifer
, is mined or extracted at a rate that exceeds the recharge rate, that is, at a rate that exceeds the practical sustained yield. Recharge usually comes from area streams, rivers and lakes. An aquifer which has been overexploited is said to be overdrafted
or depleted. Forests enhance the recharge of aquifer
s in some locales, although generally forests are a major source of aquifer depletion. Depleted aquifers can become polluted with contaminants such as nitrate
s, or permanently damaged through subsidence or through saline intrusion from the ocean.
This turns much of the world's underground water and lakes into finite resources with peak usage debates similar to oil
. These debates usually centre around agriculture and suburban water usage but generation of electricity from nuclear energy or coal and tar sands mining is also water resource intensive. A modified Hubbert curve
applies to any resource that can be harvested faster than it can be replaced. Though Hubbert's original analysis did not apply to renewable resources, their overexploitation can result in a Hubbert-like peak. This has led to the concept of peak water
.
Forest
s are overexploited when they are logged
at a rate faster than reforestation
takes place. Reforestation competes with other land uses such as food production, livestock grazing, and living space for further economic growth. Historically utilization of forest products, including timber and fuel wood, have played a key role in human societies, comparable to the roles of water and cultivable land. Today, developed countries continue to utilize timber for building houses, and wood pulp for paper
. In developing countries almost three billion people rely on wood for heating and cooking. Short-term economic gains made by conversion of forest
to agriculture, or overexploitation of wood products, typically leads to loss of long-term income and long term biological productivity. West Africa
, Madagascar
, Southeast Asia
and many other regions have experienced lower revenue because of overexploitation and the consequent declining timber harvests.
Overexploitation is one of the five main activities threatening global biodiversity
. The other four activities are pollution
, introduced species
, habitat fragmentation
and habitat destruction
.
One of the key health issues associated with biodiversity is drug discovery and the availability of medicinal resources. A significant proportion of drugs are derived, directly or indirectly, from biological sources. Marine ecosystems are of particular interest in this regard. However unregulated and inappropriate bioprospecting can be considered a form of overexploitation which has the potential to degrade ecosystems and increase biodiversity loss, as well as impacting on the rights of the communities and states from which the resources are taken.
s, as well as other groups. Excluding edible fish, the illegal trade in wildlife is valued at $10 billion per year. Industries responsible for this include the trade in bushmeat
, the trade in Chinese medicine, and the fur trade
. The Convention for International Trade in Endangered Species of Wild Fauna and Flora, or CITES was set up in order to control and regulate the trade in endangered animals. It currently protects, to a varying degree, some 33,000 species of animals and plants. It is estimated that a quarter of the endangered vertebrates in the United States of America and half of the endangered mammals is attributed to overexploitation.
All living organisms require resources to survive. Overexploitation of these resources for protracted periods can deplete natural stocks to the point where they are unable to recover within a short time frame. Humans have always harvested food and other resources they have needed to survive. Human populations, historically, were small, and methods of collection limited to small quantities. With an exponential increase in human population, expanding markets and increasing demand, combined with improved access and techniques for capture, are causing the exploitation of many species beyond sustainable levels. In practical terms, if continued, it reduces valuable resources to such low levels that their exploitation is no longer sustainable and can lead to the extinction
of a species, in addition to having dramatic, unforeseen effects
, on the ecosystem
. Overexploitation often occurs rapidly as markets open, utilising previously untapped resources, or locally used species.
Today, overexploitation and misuse of natural resources is an ever present threat for species richness
. This is more prevalent when looking at island ecology
and the species that inhabit them, as islands can be viewed as the world in miniature. Island endemic populations are more prone to extinction
from overexploitation, as they often exist at low densities with reduced reproductive rates. A good example of this are island snails, such as the Hawaiian Achatinella and the French Polynesian Partula. Achatinelline snails have 15 species listed as extinct and 24 critically endangered while 60 species of partulidae are considered extinct with 14 listed as critically endangered. The WCMC
have attributed over-collecting and very low lifetime fecundity for the extreme vulnerability exhibited among these species.
As another example, when the humble hedgehog was introduced to the Scottish island of Uist
, the population greatly expanded and took to consuming and overexploiting shorebird eggs, with drastic consequences for their breeding success. Twelve species of avifauna
are affected, with some species numbers being reduced by 39%.
Where there is substantial human migration, civil unrest, or war, controls may no longer exist. With civil unrest, for example in the Congo
and Rwanda
, firearms have become common and the breakdown of food distribution networks in such countries leaves the resources of the natural environment vulnerable. Animals are even killed as target practice, or simply to spite the government. Populations of large primates, such as gorillas and chimpanzees, ungulates and other mammals, may be reduced by 80% or more by hunting and certain species may be eliminated all together. This decline has been called the bushmeat crisis
.
Overall, 50 bird species that have become extinct since 1500 (approximately 40% of the total) have been subject to overexploitation, including:
Other species affected by overexploitation include:
Overexploitation of species can result in knock-on or cascade effect
s. This can particularly apply if, through overexploitation, a habitat loses its apex predator
. Because of the loss of the top predator, a dramatic increase
in their prey species can occur. In turn, the unchecked prey can then overexploit their own food resources until population numbers dwindle, possibly to the point of extinction.
A classic example of cascade effects occurred with sea otters. Starting before the 17th century and not phased out until 1911, sea otters were hunted aggressively for their exceptionally warm and valuable pelts, which could fetch up to $2500 US. This caused cascade effects through the kelp forest
ecosystems along the Pacific Coast of North America.
One of the sea otters’ primary food sources is the sea urchin
. When hunters caused sea otter populations to decline, an ecological release
of sea urchin populations occurred. The sea urchins then overexploited their main food source, kelp
, creating urchin barrens, areas of seabed denuded of kelp, but carpeted with urchins. No longer having food to eat, the sea urchin became locally extinct as well. Also, since kelp forest ecosystems are homes to many other species, the loss of the kelp caused other cascade effects of secondary extinctions.
In 1911, when only one small group of 32 sea otters survived in a remote cove, an international treaty was signed to prevent further exploitation of the sea otters. Under heavy protection, the otters multiplied and repopulated the depleted areas, which slowly recovered. More recently, with declining numbers of fish stocks, again due to overexploitation, killer whales have experienced a food shortage and have been observed feeding on sea otters, again reducing their numbers.
Natural resource
Natural resources occur naturally within environments that exist relatively undisturbed by mankind, in a natural form. A natural resource is often characterized by amounts of biodiversity and geodiversity existent in various ecosystems....
s such as: wild medicinal plants, grazing pasture
Pasture
Pasture is land used for grazing. Pasture lands in the narrow sense are enclosed tracts of farmland, grazed by domesticated livestock, such as horses, cattle, sheep or swine. The vegetation of tended pasture, forage, consists mainly of grasses, with an interspersion of legumes and other forbs...
s, fish stocks, forests and water aquifers
Aquifer
An aquifer is a wet underground layer of water-bearing permeable rock or unconsolidated materials from which groundwater can be usefully extracted using a water well. The study of water flow in aquifers and the characterization of aquifers is called hydrogeology...
.
In ecology
Ecology
Ecology is the scientific study of the relations that living organisms have with respect to each other and their natural environment. Variables of interest to ecologists include the composition, distribution, amount , number, and changing states of organisms within and among ecosystems...
, overexploitation describes one of the five main activities threatening global biodiversity
Biodiversity
Biodiversity is the degree of variation of life forms within a given ecosystem, biome, or an entire planet. Biodiversity is a measure of the health of ecosystems. Biodiversity is in part a function of climate. In terrestrial habitats, tropical regions are typically rich whereas polar regions...
. Ecologists use the term to describe populations that are harvested at a rate that is unsustainable, given their natural rates of mortality and capacities for reproduction. This can result in extinction at the population level and even extinction of whole species. In conservation biology
Conservation biology
Conservation biology is the scientific study of the nature and status of Earth's biodiversity with the aim of protecting species, their habitats, and ecosystems from excessive rates of extinction...
the term is usually used in the context of human economic activity that involves the taking of biological resources, or organisms, in larger numbers than their populations can withstand. The term is also used and defined somewhat differently in fisheries, hydrology
Hydrology
Hydrology is the study of the movement, distribution, and quality of water on Earth and other planets, including the hydrologic cycle, water resources and environmental watershed sustainability...
and natural resource management
Natural resource management
Natural resource management refers to the management of natural resources such as land, water, soil, plants and animals, with a particular focus on how management affects the quality of life for both present and future generations ....
.
Overexploitation can lead to resource destruction, including extinction
Extinction
In biology and ecology, extinction is the end of an organism or of a group of organisms , normally a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and recover may have been lost before this point...
s. However it is also possible for overexploitation to be sustainable, as discussed below in the section on fisheries. In the context of fishing, the term overfishing
Overfishing
Overfishing occurs when fishing activities reduce fish stocks below an acceptable level. This can occur in any body of water from a pond to the oceans....
can be used instead of overexploitation, as can overgrazing
Overgrazing
Overgrazing occurs when plants are exposed to intensive grazing for extended periods of time, or without sufficient recovery periods. It can be caused by either livestock in poorly managed agricultural applications, or by overpopulations of native or non-native wild animals.Overgrazing reduces the...
in stock management
Stock management
Stock management is the function of understanding the stock mix of a company and the different demands on that stock. The demands are influenced by both external and internal factors and are balanced by the creation of Purchase order requests to keep supplies at a reasonable or prescribed...
, overlogging in forest management
Forest management
200px|thumb|right|[[Sustainable development|Sustainable]] forest management carried out by [[Complejo Forestal y Maderero Panguipulli|Complejo Panguipulli]] has contributed to the preservation of the forested landscape around [[Neltume]], a sawmill town in Chile...
, overdrafting
Overdrafting
Overdrafting is the process of extracting groundwater beyond the safe yield or equilibrium yield of the aquifer.Since every groundwater basin recharges at a different rate depending upon precipitation, vegetative cover and soil conservation practises, the quantity of groundwater that can be safely...
in aquifer management, and endangered species
Endangered species
An endangered species is a population of organisms which is at risk of becoming extinct because it is either few in numbers, or threatened by changing environmental or predation parameters...
in species monitoring. Overexploitation is not an activity limited to humans. Introduced predators and herbivores, for example, can overexploit native flora
Flora
Flora is the plant life occurring in a particular region or time, generally the naturally occurring or indigenous—native plant life. The corresponding term for animals is fauna.-Etymology:...
and fauna
Fauna
Fauna or faunæ is all of the animal life of any particular region or time. The corresponding term for plants is flora.Zoologists and paleontologists use fauna to refer to a typical collection of animals found in a specific time or place, e.g. the "Sonoran Desert fauna" or the "Burgess shale fauna"...
.
History
Mamo
A mamo or hoohoo is a bird of the genus Drepanis. These nectarivorous finches were endemic to Hawaii but are now extinct.The Hawaiian name may be related to the name of the ōō , a bird with a similar appearance...
bird; a single cloak used the feathers of 70,000 birds of this now-extinct species. The dodo
Dodo
The dodo was a flightless bird endemic to the Indian Ocean island of Mauritius. Related to pigeons and doves, it stood about a meter tall, weighing about , living on fruit, and nesting on the ground....
, a flightless bird from Mauritius
Mauritius
Mauritius , officially the Republic of Mauritius is an island nation off the southeast coast of the African continent in the southwest Indian Ocean, about east of Madagascar...
, is another well known example of overexploitation. As with many island species, it was naive about certain predators, allowing humans to approach and kill it with ease.
From the earliest of times, hunting
Hunting
Hunting is the practice of pursuing any living thing, usually wildlife, for food, recreation, or trade. In present-day use, the term refers to lawful hunting, as distinguished from poaching, which is the killing, trapping or capture of the hunted species contrary to applicable law...
for wild mammal
Mammal
Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...
s and bird
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
s has been an important human activity as a means of survival. There is a whole history of overexploitation in the form of overhunting. The overkill hypothesis (Quaternary extinction event
Quaternary extinction event
The Quaternary period saw the extinctions of numerous predominantly larger, especially megafaunal, species, many of which occurred during the transition from the Pleistocene to the Holocene epoch. However, the extinction wave did not stop at the end of the Pleistocene, but continued especially on...
s) explains why the megafauna
Megafauna
In terrestrial zoology, megafauna are "giant", "very large" or "large" animals. The most common thresholds used are or...
l extinctions occurred within a relatively short period of time. This can be traced with human migration
Human migration
Human migration is physical movement by humans from one area to another, sometimes over long distances or in large groups. Historically this movement was nomadic, often causing significant conflict with the indigenous population and their displacement or cultural assimilation. Only a few nomadic...
. The most convincing evidence of this theory is that 80% of the North American large mammal species disappeared within 1000 years of the arrival of humans on the western hemisphere continents. Again, in New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...
, ten species of the giant moa birds
Moa
The moa were eleven species of flightless birds endemic to New Zealand. The two largest species, Dinornis robustus and Dinornis novaezelandiae, reached about in height with neck outstretched, and weighed about ....
were hunted to extinction by the Māori by 1500 AD. A second wave of extinctions occurred later with European settlement.
In more recent times, overexploitation has resulted in the gradual emergence of the concepts of sustainability
Sustainability
Sustainability is the capacity to endure. For humans, sustainability is the long-term maintenance of well being, which has environmental, economic, and social dimensions, and encompasses the concept of union, an interdependent relationship and mutual responsible position with all living and non...
and sustainable development
Sustainable development
Sustainable development is a pattern of resource use, that aims to meet human needs while preserving the environment so that these needs can be met not only in the present, but also for generations to come...
, which has built on other concepts, such as sustainable yield
Sustainable yield
The sustainable yield of natural capital is the ecological yield that can be extracted without reducing the base of capital itself, i.e. the surplus required to maintain ecosystem services at the same or increasing level over time. This yield usually varies over time with the needs of the...
, eco-development and deep ecology
Deep ecology
Deep ecology is a contemporary ecological philosophy that recognizes an inherent worth of all living beings, regardless of their instrumental utility to human needs. The philosophy emphasizes the interdependence of organisms within ecosystems and that of ecosystems with each other within the...
.
Overview
Overexploitation need not necessarily lead to the destruction of the resource, nor is it necessarily unsustainable. However, depleting the numbers or amount of the resource can change its quality. For example, footstool palmLivistona rotundifolia
Livistona rotundifolia is a round-leaf fountain palm found in Southeast Asia. It is a member of the genus Livistona. It is also called Footstool palm and Anáhaw . It is the unofficial national leaf of the Philippines....
is a wild palm tree found in Southeast Asia. Its leaves are used for thatching and food wrapping, and overharvesting has resulted in its leaf size becoming smaller.
Tragedy of the commons
The tragedy of the commonsTragedy of the commons
The tragedy of the commons is a dilemma arising from the situation in which multiple individuals, acting independently and rationally consulting their own self-interest, will ultimately deplete a shared limited resource, even when it is clear that it is not in anyone's long-term interest for this...
refers to a dilemma described in an article by that name written by Garrett Hardin
Garrett Hardin
Garrett James Hardin was an American ecologist who warned of the dangers of overpopulation and whose concept of the tragedy of the commons brought attention to "the damage that innocent actions by individuals can inflict on the environment"...
and first published in the journal Science
Science (journal)
Science is the academic journal of the American Association for the Advancement of Science and is one of the world's top scientific journals....
in 1968.
Central to Hardin's essay is an example which is a useful parable for understanding how overexploitation can occur. This example was first sketched in an 1833 pamphlet by William Forster Lloyd
William Forster Lloyd
William Forster Lloyd FRS was a British writer on economics.He was educated at Westminster School and Christ Church, Oxford, graduating BA in 1815 and MA in 1818....
, as a hypothetical and simplified situation based on medieval land tenure
Land tenure
Land tenure is the name given, particularly in common law systems, to the legal regime in which land is owned by an individual, who is said to "hold" the land . The sovereign monarch, known as The Crown, held land in its own right. All private owners are either its tenants or sub-tenants...
in Europe, of herders sharing a common
Common land
Common land is land owned collectively or by one person, but over which other people have certain traditional rights, such as to allow their livestock to graze upon it, to collect firewood, or to cut turf for fuel...
on which they are each entitled to let their cows graze. In Hardin's example, it is in each herder's interest to put each succeeding cow he acquires onto the land, even if the carrying capacity
Carrying capacity
The carrying capacity of a biological species in an environment is the maximum population size of the species that the environment can sustain indefinitely, given the food, habitat, water and other necessities available in the environment...
of the common is exceeded and it is temporarily or permanently damaged for all as a result. The herder receives all of the benefits from an additional cow, while the damage to the common is shared by the entire group. If all herders make this individually rational economic decision, the common will be overexploited or even destroyed to the detriment of all. However, since all herders reach the same rational conclusion, overexploitation in the form of overgrazing
Overgrazing
Overgrazing occurs when plants are exposed to intensive grazing for extended periods of time, or without sufficient recovery periods. It can be caused by either livestock in poorly managed agricultural applications, or by overpopulations of native or non-native wild animals.Overgrazing reduces the...
occurs, with immediate losses, and the pasture may be degraded to the point where it gives very little return.
"Therein is the tragedy. Each man is locked into a system that compels him to increase his herd without limit—in a world that is limited. Ruin is the destination toward which all men rush, each pursuing his own interest in a society that believes in the freedom of the commons." (Hardin, 1968)
In the course of his essay, Hardin develops the theme, drawing in many examples of latter day commons, such as national park
National park
A national park is a reserve of natural, semi-natural, or developed land that a sovereign state declares or owns. Although individual nations designate their own national parks differently A national park is a reserve of natural, semi-natural, or developed land that a sovereign state declares or...
s, the atmosphere, oceans, rivers and fish stocks. The example of fish stocks had led some to call this the "tragedy of the fishers". A major theme running through the essay is the growth of human populations, with the Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
's finite resources being the general common.
The tragedy of the commons has intellectual roots tracing back to Aristotle
Aristotle
Aristotle was a Greek philosopher and polymath, a student of Plato and teacher of Alexander the Great. His writings cover many subjects, including physics, metaphysics, poetry, theater, music, logic, rhetoric, linguistics, politics, government, ethics, biology, and zoology...
, who noted that "what is common to the greatest number has the least care bestowed upon it", as well as to Hobbes and his leviathan
Leviathan (book)
Leviathan or The Matter, Forme and Power of a Common Wealth Ecclesiasticall and Civil — commonly called simply Leviathan — is a book written by Thomas Hobbes and published in 1651. Its name derives from the biblical Leviathan...
. The opposite situation to a tragedy of the commons is sometimes referred to as a tragedy of the anticommons
Tragedy of the anticommons
The tragedy of the anticommons is a neologism coined by Michael Heller to describe a coordination breakdown where the existence of numerous rightsholders frustrates achieving a socially desirable outcome. The term mirrors the older term tragedy of the commons used to describe coordination...
: a situation in which rational individuals, acting separately, collectively waste a given resource by underutilizing it.
The tragedy of the commons can be avoided if it is appropriately regulated. Hardin's use of "commons" has frequently been misunderstood, leading Hardin to later remark that he should have titled his work "The tragedy of the unregulated commons".
Fisheries
Overfishing
Overfishing occurs when fishing activities reduce fish stocks below an acceptable level. This can occur in any body of water from a pond to the oceans....
occurs when a fish stock
Fish stock
Fish stocks are subpopulations of a particular species of fish, for which intrinsic parameters are the only significant factors in determining population dynamics, while extrinsic factors are considered to be insignificant.-The stock concept:All species have geographic limits to their...
has been fished down "below the size that, on average, would support the long-term maximum sustainable yield
Maximum sustainable yield
In population ecology and economics, maximum sustainable yield or MSY is, theoretically, the largest yield that can be taken from a species' stock over an indefinite period...
of the fishery". However, overexploitation can be sustainable.
When a fishery starts harvesting fish from a previously unexploited stock, the biomass
Biomass (ecology)
Biomass, in ecology, is the mass of living biological organisms in a given area or ecosystem at a given time. Biomass can refer to species biomass, which is the mass of one or more species, or to community biomass, which is the mass of all species in the community. It can include microorganisms,...
of the fish stock will decrease, since harvesting means fish are being removed. For sustainability, the rate at which the fish replenish biomass through reproduction must balance the rate at which the fish are being harvested. If the harvest rate is increased, then the stock biomass will further decrease. At a certain point, the maximum harvest yield that can be sustained will be reached, and further attempts to increase the harvest rate will result in the collapse of the fishery. This point is called the maximum sustainable yield
Maximum sustainable yield
In population ecology and economics, maximum sustainable yield or MSY is, theoretically, the largest yield that can be taken from a species' stock over an indefinite period...
, and in practice, usually occurs when the fishery has been fished down to about 30% of the biomass it had before harvesting started.
It is possible to fish the stock down further to, say, 15% of the pre-harvest biomass, and then adjust the harvest rate so the biomass remains at that level. In this case, the fishery is sustainable, but is now overexploited, because the stock has been run down to the point where the sustainable yield is less than it could be.
Fish stocks are said to "collapse" if their biomass declines by more than 95 percent of their maximum historical biomass. Atlantic cod
Atlantic cod
The Atlantic cod, Gadus morhua, is a well-known demersal food fish belonging to the family Gadidae. It is also commercially known as cod, codling or haberdine....
stocks were severely overexploited in the 1970s and 1980s, leading to their abrupt collapse in 1992. Even though fishing has ceased, the cod stocks have failed to recover. The absence of cod as the apex predator
Apex predator
Apex predators are predators that have no predators of their own, residing at the top of their food chain. Zoologists define predation as the killing and consumption of another organism...
in many areas has led to trophic cascade
Trophic cascade
Trophic cascades occur when predators in a food web suppress the abundance of their prey, thereby releasing the next lower trophic level from predation...
s.
About 25% of world fisheries are now overexploited to the point where their current biomass is less than the level that maximizes their sustainable yield. These depleted fisheries can often recover if fishing pressure is reduced until the stock biomass returns to the optimal biomass. At this point, harvesting can be resumed near the maximum sustainable yield.
The tragedy of the commons
Tragedy of the commons
The tragedy of the commons is a dilemma arising from the situation in which multiple individuals, acting independently and rationally consulting their own self-interest, will ultimately deplete a shared limited resource, even when it is clear that it is not in anyone's long-term interest for this...
can be avoided within the context of fisheries if fishing effort and practices are regulated appropriately by fisheries management
Fisheries management
Fisheries management draws on fisheries science in order to find ways to protect fishery resources so sustainable exploitation is possible. Modern fisheries management is often referred to as a governmental system of appropriate management rules based on defined objectives and a mix of management...
. One effective approach may be assigning some measure of ownership in the form of individual transferable quotas (ITQs) to fishermen. In 2008, a large scale study of fisheries that used ITQs, and ones that didn't, provided strong evidence that ITQs help prevent collapses and restore fisheries that appear to be in decline.
Water resources
Lake
A lake is a body of relatively still fresh or salt water of considerable size, localized in a basin, that is surrounded by land. Lakes are inland and not part of the ocean and therefore are distinct from lagoons, and are larger and deeper than ponds. Lakes can be contrasted with rivers or streams,...
s and aquifer
Aquifer
An aquifer is a wet underground layer of water-bearing permeable rock or unconsolidated materials from which groundwater can be usefully extracted using a water well. The study of water flow in aquifers and the characterization of aquifers is called hydrogeology...
s, are usually renewable resources which naturally recharge (the term fossil water
Fossil water
Fossil water or paleowater is groundwater that has remained sealed in an aquifer for a long period of time. Water can rest underground in "fossil aquifers" for thousands or even millions of years...
is sometimes used to describe aquifers which don't recharge). Overexploitation occurs if a water resource, such as the Ogallala Aquifer
Ogallala Aquifer
The Ogallala Aquifer, also known as the High Plains Aquifer, is a vast yet shallow underground water table aquifer located beneath the Great Plains in the United States...
, is mined or extracted at a rate that exceeds the recharge rate, that is, at a rate that exceeds the practical sustained yield. Recharge usually comes from area streams, rivers and lakes. An aquifer which has been overexploited is said to be overdrafted
Overdrafting
Overdrafting is the process of extracting groundwater beyond the safe yield or equilibrium yield of the aquifer.Since every groundwater basin recharges at a different rate depending upon precipitation, vegetative cover and soil conservation practises, the quantity of groundwater that can be safely...
or depleted. Forests enhance the recharge of aquifer
Aquifer
An aquifer is a wet underground layer of water-bearing permeable rock or unconsolidated materials from which groundwater can be usefully extracted using a water well. The study of water flow in aquifers and the characterization of aquifers is called hydrogeology...
s in some locales, although generally forests are a major source of aquifer depletion. Depleted aquifers can become polluted with contaminants such as nitrate
Nitrate
The nitrate ion is a polyatomic ion with the molecular formula NO and a molecular mass of 62.0049 g/mol. It is the conjugate base of nitric acid, consisting of one central nitrogen atom surrounded by three identically-bonded oxygen atoms in a trigonal planar arrangement. The nitrate ion carries a...
s, or permanently damaged through subsidence or through saline intrusion from the ocean.
This turns much of the world's underground water and lakes into finite resources with peak usage debates similar to oil
Peak oil
Peak oil is the point in time when the maximum rate of global petroleum extraction is reached, after which the rate of production enters terminal decline. This concept is based on the observed production rates of individual oil wells, projected reserves and the combined production rate of a field...
. These debates usually centre around agriculture and suburban water usage but generation of electricity from nuclear energy or coal and tar sands mining is also water resource intensive. A modified Hubbert curve
Hubbert curve
The Hubbert curve is an approximation of the production rate of a resource over time. It is a symmetric logistic distribution curve, often confused with the "normal" gaussian function. It first appeared in "Nuclear Energy and the Fossil Fuels," geophysicist M...
applies to any resource that can be harvested faster than it can be replaced. Though Hubbert's original analysis did not apply to renewable resources, their overexploitation can result in a Hubbert-like peak. This has led to the concept of peak water
Peak water
The term Peak Water has been put forward as a concept to help understand growing constraints on the availability, quality, and use of freshwater resources...
.
Forest resources
Forest
A forest, also referred to as a wood or the woods, is an area with a high density of trees. As with cities, depending where you are in the world, what is considered a forest may vary significantly in size and have various classification according to how and what of the forest is composed...
s are overexploited when they are logged
Logging
Logging is the cutting, skidding, on-site processing, and loading of trees or logs onto trucks.In forestry, the term logging is sometimes used in a narrow sense concerning the logistics of moving wood from the stump to somewhere outside the forest, usually a sawmill or a lumber yard...
at a rate faster than reforestation
Reforestation
Reforestation is the natural or intentional restocking of existing forests and woodlands that have been depleted, usually through deforestation....
takes place. Reforestation competes with other land uses such as food production, livestock grazing, and living space for further economic growth. Historically utilization of forest products, including timber and fuel wood, have played a key role in human societies, comparable to the roles of water and cultivable land. Today, developed countries continue to utilize timber for building houses, and wood pulp for paper
Paper
Paper is a thin material mainly used for writing upon, printing upon, drawing or for packaging. It is produced by pressing together moist fibers, typically cellulose pulp derived from wood, rags or grasses, and drying them into flexible sheets....
. In developing countries almost three billion people rely on wood for heating and cooking. Short-term economic gains made by conversion of forest
Deforestation
Deforestation is the removal of a forest or stand of trees where the land is thereafter converted to a nonforest use. Examples of deforestation include conversion of forestland to farms, ranches, or urban use....
to agriculture, or overexploitation of wood products, typically leads to loss of long-term income and long term biological productivity. West Africa
West Africa
West Africa or Western Africa is the westernmost region of the African continent. Geopolitically, the UN definition of Western Africa includes the following 16 countries and an area of approximately 5 million square km:-Flags of West Africa:...
, Madagascar
Madagascar
The Republic of Madagascar is an island country located in the Indian Ocean off the southeastern coast of Africa...
, Southeast Asia
Southeast Asia
Southeast Asia, South-East Asia, South East Asia or Southeastern Asia is a subregion of Asia, consisting of the countries that are geographically south of China, east of India, west of New Guinea and north of Australia. The region lies on the intersection of geological plates, with heavy seismic...
and many other regions have experienced lower revenue because of overexploitation and the consequent declining timber harvests.
Biodiversity
Biodiversity
Biodiversity is the degree of variation of life forms within a given ecosystem, biome, or an entire planet. Biodiversity is a measure of the health of ecosystems. Biodiversity is in part a function of climate. In terrestrial habitats, tropical regions are typically rich whereas polar regions...
. The other four activities are pollution
Pollution
Pollution is the introduction of contaminants into a natural environment that causes instability, disorder, harm or discomfort to the ecosystem i.e. physical systems or living organisms. Pollution can take the form of chemical substances or energy, such as noise, heat or light...
, introduced species
Introduced species
An introduced species — or neozoon, alien, exotic, non-indigenous, or non-native species, or simply an introduction, is a species living outside its indigenous or native distributional range, and has arrived in an ecosystem or plant community by human activity, either deliberate or accidental...
, habitat fragmentation
Habitat fragmentation
Habitat fragmentation as the name implies, describes the emergence of discontinuities in an organism's preferred environment , causing population fragmentation...
and habitat destruction
Habitat destruction
Habitat destruction is the process in which natural habitat is rendered functionally unable to support the species present. In this process, the organisms that previously used the site are displaced or destroyed, reducing biodiversity. Habitat destruction by human activity mainly for the purpose of...
.
One of the key health issues associated with biodiversity is drug discovery and the availability of medicinal resources. A significant proportion of drugs are derived, directly or indirectly, from biological sources. Marine ecosystems are of particular interest in this regard. However unregulated and inappropriate bioprospecting can be considered a form of overexploitation which has the potential to degrade ecosystems and increase biodiversity loss, as well as impacting on the rights of the communities and states from which the resources are taken.
Endangered species
Overexploitation threatens one-third of endangered vertebrateVertebrate
Vertebrates are animals that are members of the subphylum Vertebrata . Vertebrates are the largest group of chordates, with currently about 58,000 species described. Vertebrates include the jawless fishes, bony fishes, sharks and rays, amphibians, reptiles, mammals, and birds...
s, as well as other groups. Excluding edible fish, the illegal trade in wildlife is valued at $10 billion per year. Industries responsible for this include the trade in bushmeat
Bushmeat
Bushmeat initially referred to the hunting of wild animals in West and Central Africa and is a calque from the French viande de brousse. Today the term is commonly used for meat of terrestrial wild animals, killed for subsistence or commercial purposes throughout the humid tropics of the Americas,...
, the trade in Chinese medicine, and the fur trade
Fur trade
The fur trade is a worldwide industry dealing in the acquisition and sale of animal fur. Since the establishment of world market for in the early modern period furs of boreal, polar and cold temperate mammalian animals have been the most valued...
. The Convention for International Trade in Endangered Species of Wild Fauna and Flora, or CITES was set up in order to control and regulate the trade in endangered animals. It currently protects, to a varying degree, some 33,000 species of animals and plants. It is estimated that a quarter of the endangered vertebrates in the United States of America and half of the endangered mammals is attributed to overexploitation.
All living organisms require resources to survive. Overexploitation of these resources for protracted periods can deplete natural stocks to the point where they are unable to recover within a short time frame. Humans have always harvested food and other resources they have needed to survive. Human populations, historically, were small, and methods of collection limited to small quantities. With an exponential increase in human population, expanding markets and increasing demand, combined with improved access and techniques for capture, are causing the exploitation of many species beyond sustainable levels. In practical terms, if continued, it reduces valuable resources to such low levels that their exploitation is no longer sustainable and can lead to the extinction
Extinction
In biology and ecology, extinction is the end of an organism or of a group of organisms , normally a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and recover may have been lost before this point...
of a species, in addition to having dramatic, unforeseen effects
Keystone species
A keystone species is a species that has a disproportionately large effect on its environment relative to its abundance. Such species play a critical role in maintaining the structure of an ecological community, affecting many other organisms in an ecosystem and helping to determine the types and...
, on the ecosystem
Ecosystem
An ecosystem is a biological environment consisting of all the organisms living in a particular area, as well as all the nonliving , physical components of the environment with which the organisms interact, such as air, soil, water and sunlight....
. Overexploitation often occurs rapidly as markets open, utilising previously untapped resources, or locally used species.
Species richness
Species richness is the number of different species in a given area. It is represented in equation form as S.Species richness is the fundamental unit in which to assess the homogeneity of an environment. Typically, species richness is used in conservation studies to determine the sensitivity of...
. This is more prevalent when looking at island ecology
Island Ecology
Island ecology is the study of island organisms and their interactions with each other and the environment. Islands account for nearly 1/6 of earth’s total land area, yet the ecology of island ecosystems is vastly different from that of mainland communities. Their isolation and high availability...
and the species that inhabit them, as islands can be viewed as the world in miniature. Island endemic populations are more prone to extinction
Extinction
In biology and ecology, extinction is the end of an organism or of a group of organisms , normally a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and recover may have been lost before this point...
from overexploitation, as they often exist at low densities with reduced reproductive rates. A good example of this are island snails, such as the Hawaiian Achatinella and the French Polynesian Partula. Achatinelline snails have 15 species listed as extinct and 24 critically endangered while 60 species of partulidae are considered extinct with 14 listed as critically endangered. The WCMC
World Conservation Monitoring Centre
The United Nations Environment Programme's World Conservation Monitoring Centre is an executive agency of the United Nations Environment Programme, based in Cambridge in the United Kingdom. UNEP-WCMC has been part of UNEP since 2000, and has responsibility for biodiversity assessment and support...
have attributed over-collecting and very low lifetime fecundity for the extreme vulnerability exhibited among these species.
As another example, when the humble hedgehog was introduced to the Scottish island of Uist
Uist
Uist or The Uists are the central group of islands in the Outer Hebrides of Scotland.North Uist and South Uist are linked by causeways running via Benbecula and Grimsay, and the entire group is sometimes known as the Uists....
, the population greatly expanded and took to consuming and overexploiting shorebird eggs, with drastic consequences for their breeding success. Twelve species of avifauna
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
are affected, with some species numbers being reduced by 39%.
Where there is substantial human migration, civil unrest, or war, controls may no longer exist. With civil unrest, for example in the Congo
Democratic Republic of the Congo
The Democratic Republic of the Congo is a state located in Central Africa. It is the second largest country in Africa by area and the eleventh largest in the world...
and Rwanda
Rwanda
Rwanda or , officially the Republic of Rwanda , is a country in central and eastern Africa with a population of approximately 11.4 million . Rwanda is located a few degrees south of the Equator, and is bordered by Uganda, Tanzania, Burundi and the Democratic Republic of the Congo...
, firearms have become common and the breakdown of food distribution networks in such countries leaves the resources of the natural environment vulnerable. Animals are even killed as target practice, or simply to spite the government. Populations of large primates, such as gorillas and chimpanzees, ungulates and other mammals, may be reduced by 80% or more by hunting and certain species may be eliminated all together. This decline has been called the bushmeat crisis
Bushmeat
Bushmeat initially referred to the hunting of wild animals in West and Central Africa and is a calque from the French viande de brousse. Today the term is commonly used for meat of terrestrial wild animals, killed for subsistence or commercial purposes throughout the humid tropics of the Americas,...
.
Overall, 50 bird species that have become extinct since 1500 (approximately 40% of the total) have been subject to overexploitation, including:
- Great Auk – The penguin-like bird of the north, hunted for its feathers, meat, fat and oil.
- Carolina parakeetCarolina ParakeetThe Carolina Parakeet was the only parrot species native to the eastern United States. It was found from the Ohio Valley to the Gulf of Mexico, and lived in old forests along rivers. It was the only species at the time classified in the genus Conuropsis...
– The only parrot species native to the eastern United States, was hunted for crop protection and its feathers.
Other species affected by overexploitation include:
- The international trade in fur: chinchillaChinchillaChinchillas are crepuscular rodents, slightly larger and more robust than ground squirrels, and are native to the Andes mountains in South America. Along with their relatives, viscachas, they make up the family Chinchillidae....
, vicuñaVicuñaThe vicuña or vicugna is one of two wild South American camelids, along with the guanaco, which live in the high alpine areas of the Andes. It is a relative of the llama, and is now believed to share a wild ancestor with domesticated alpacas, which are raised for their fibre...
, giant otterGiant OtterThe giant otter is a South American carnivorous mammal. It is the longest member of the Mustelidae, or weasel family, a globally successful group of predators. Unusually for a mustelid, the giant otter is a social species, with family groups typically supporting three to eight members...
and numerous cat species. - Insect collectors: butterflies
- Horticulturists: New Zealand mistletoe (Trilepidia adamsii), orchids, cacti and many other plant species.
- Shell collectors: Marine molluscs
- Aquarium hobbyists: tropical fishTropical fishTropical fish include fish found in tropical environments around the world, including both freshwater and salt water species.Tropical fish are popular as aquarium fish, due to their often bright coloration...
- Chinese medicine: bears, tigers
- Novelty pets: snakes, parrots and primates
Cascade effects
Cascade effect
A Cascade Effect is an unforeseen chain of events due to an act affecting a system. If there is a possibility that the cascade effect will have a negative impact on the system, it is possible to analyze the effects with a consequence/impact analysis...
s. This can particularly apply if, through overexploitation, a habitat loses its apex predator
Apex predator
Apex predators are predators that have no predators of their own, residing at the top of their food chain. Zoologists define predation as the killing and consumption of another organism...
. Because of the loss of the top predator, a dramatic increase
Overpopulation in wild animals
Overpopulation in wild animals occurs when a population of a wild species exceeds the carrying capacity of its ecological niche. Overpopulation is a function of the number of individuals compared to the relevant resources, such as the water and essential nutrients they need to survive.In the...
in their prey species can occur. In turn, the unchecked prey can then overexploit their own food resources until population numbers dwindle, possibly to the point of extinction.
A classic example of cascade effects occurred with sea otters. Starting before the 17th century and not phased out until 1911, sea otters were hunted aggressively for their exceptionally warm and valuable pelts, which could fetch up to $2500 US. This caused cascade effects through the kelp forest
Kelp forest
Kelp forests are underwater areas with a high density of kelp. They are recognized as one of the most productive and dynamic ecosystems on Earth. Smaller areas of anchored kelp are called kelp beds....
ecosystems along the Pacific Coast of North America.
One of the sea otters’ primary food sources is the sea urchin
Sea urchin
Sea urchins or urchins are small, spiny, globular animals which, with their close kin, such as sand dollars, constitute the class Echinoidea of the echinoderm phylum. They inhabit all oceans. Their shell, or "test", is round and spiny, typically from across. Common colors include black and dull...
. When hunters caused sea otter populations to decline, an ecological release
Ecological release
Ecological release occurs when a species is introduced to an environment other than its native habitat, the foreign species will either establish a local population, or die out from the region...
of sea urchin populations occurred. The sea urchins then overexploited their main food source, kelp
Kelp
Kelps are large seaweeds belonging to the brown algae in the order Laminariales. There are about 30 different genera....
, creating urchin barrens, areas of seabed denuded of kelp, but carpeted with urchins. No longer having food to eat, the sea urchin became locally extinct as well. Also, since kelp forest ecosystems are homes to many other species, the loss of the kelp caused other cascade effects of secondary extinctions.
In 1911, when only one small group of 32 sea otters survived in a remote cove, an international treaty was signed to prevent further exploitation of the sea otters. Under heavy protection, the otters multiplied and repopulated the depleted areas, which slowly recovered. More recently, with declining numbers of fish stocks, again due to overexploitation, killer whales have experienced a food shortage and have been observed feeding on sea otters, again reducing their numbers.
See also
- BiodiversityBiodiversityBiodiversity is the degree of variation of life forms within a given ecosystem, biome, or an entire planet. Biodiversity is a measure of the health of ecosystems. Biodiversity is in part a function of climate. In terrestrial habitats, tropical regions are typically rich whereas polar regions...
- Carrying capacityCarrying capacityThe carrying capacity of a biological species in an environment is the maximum population size of the species that the environment can sustain indefinitely, given the food, habitat, water and other necessities available in the environment...
- Common-pool resourceCommon-pool resourceIn economics, a common-pool resource , also called a common property resource, is a type of good consisting of a natural or human-made resource system , whose size or characteristics makes it costly, but not impossible, to exclude potential beneficiaries from obtaining benefits from its use...
- Conservation biologyConservation biologyConservation biology is the scientific study of the nature and status of Earth's biodiversity with the aim of protecting species, their habitats, and ecosystems from excessive rates of extinction...
- Critical depensationCritical depensationIn population dynamics, depensation is the effect on a population whereby, due to certain causes, a decrease in the breeding population leads to reduced survival and production of eggs or offspring...
- DeforestationDeforestationDeforestation is the removal of a forest or stand of trees where the land is thereafter converted to a nonforest use. Examples of deforestation include conversion of forestland to farms, ranches, or urban use....
- Ecosystem managementEcosystem managementEcosystem management is a process that aims to conserve major ecological services and restore natural resources while meeting the socioeconomic, political and cultural needs of current and future generations. The principal objective of ecosystem management is the efficient maintenance, and ethical...
- EnclosureEnclosureEnclosure or inclosure is the process which ends traditional rights such as mowing meadows for hay, or grazing livestock on common land. Once enclosed, these uses of the land become restricted to the owner, and it ceases to be common land. In England and Wales the term is also used for the...
- Exploitation of natural resourcesExploitation of natural resourcesMain article: OverexploitationSome exploitation of natural resources is an essential condition of the human existence. This refers primarily to food production and necessities...
- ExtinctionExtinctionIn biology and ecology, extinction is the end of an organism or of a group of organisms , normally a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and recover may have been lost before this point...
- Huffaker's mite experiment
- Inverse commons
- Occupancy-abundance relationshipOccupancy-abundance relationshipIn macroecology, the occupancy-abundance relationship is the relationship between the abundance of species and the size of their ranges within a region. This relationship is perhaps one of the most well-documented relationships in macroecology, and applies both intra- and interspecifically . In...
- Our Plundered PlanetOur Plundered PlanetWIKIPEDIA Our Plundered Planet is a book published in 1948 that was written by Fairfield Osborn about environmental destruction by humankind. The book is a critique of humankind's poor stewardship of Earth. It typifies the earliest apocalyptic environmental literature, in which human beings are...
- Over-consumptionOver-consumptionOver-consumption is a situation where resource-use has outpaced the sustainable capacity of the ecosystem. A prolonged pattern of overconsumption leads to inevitable environmental degradation and the eventual loss of resource bases...
- OverfishingOverfishingOverfishing occurs when fishing activities reduce fish stocks below an acceptable level. This can occur in any body of water from a pond to the oceans....
- OvergrazingOvergrazingOvergrazing occurs when plants are exposed to intensive grazing for extended periods of time, or without sufficient recovery periods. It can be caused by either livestock in poorly managed agricultural applications, or by overpopulations of native or non-native wild animals.Overgrazing reduces the...
- Overpopulation in wild animalsOverpopulation in wild animalsOverpopulation in wild animals occurs when a population of a wild species exceeds the carrying capacity of its ecological niche. Overpopulation is a function of the number of individuals compared to the relevant resources, such as the water and essential nutrients they need to survive.In the...
- Social dilemmaSocial dilemmaSocial dilemmas are situations in which collective interests are at odds with private interests. Such situations arise when faced with prioritizing either short-term selfish interests or the long-term interests of a group, organization, or society. Many of the most challenging issues, from the...
- Social trapSocial trapSocial trap is a term used by psychologists to describe a situation in which a group of people act to obtain short-term individual gains, which in the long run leads to a loss for the group as a whole...
- SustainabilitySustainabilitySustainability is the capacity to endure. For humans, sustainability is the long-term maintenance of well being, which has environmental, economic, and social dimensions, and encompasses the concept of union, an interdependent relationship and mutual responsible position with all living and non...
- Tragedy of the commonsTragedy of the commonsThe tragedy of the commons is a dilemma arising from the situation in which multiple individuals, acting independently and rationally consulting their own self-interest, will ultimately deplete a shared limited resource, even when it is clear that it is not in anyone's long-term interest for this...
- Tragedy of the anticommonsTragedy of the anticommonsThe tragedy of the anticommons is a neologism coined by Michael Heller to describe a coordination breakdown where the existence of numerous rightsholders frustrates achieving a socially desirable outcome. The term mirrors the older term tragedy of the commons used to describe coordination...
- Tyranny of small decisionsTyranny of small decisionsThe tyranny of small decisions refers to a phenomenon explored in an essay by that name, published in 1966 by the American economist Alfred E. Kahn. The article describes a situation where a number of decisions, individually small in size and time perspective, cumulatively result in an outcome...