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The carrying capacity of a biological species

Species

In biology, a species is:* a taxonomic rank or* a unit at that rank ....

in an environment

Natural environment

The natural environment, commonly referred to simply as the environment, is a term that encompasses all living and non-living things occurring naturally on Earth or some region thereof....

is the population size of the species that the environment can sustain indefinitely, given the food, habitat

Habitat

The term habitat has a number of meanings:* Habitat , a place where a species lives and grows** Human habitat, a place where humans live, work or play** Space habitat, a space station intended as a permanent settlement...

, water

Drinking water

Drinking water or potable water is water of sufficiently high quality that it can be consumed or used without risk of immediate or long term harm...

and other necessities available in the environment. For the human population, more complex variables such as sanitation

Sanitation

Sanitation is the hygienic means of promoting health through prevention of human contact with the hazards of wastes. Hazards can be either physical, microbiological, biological or chemical agents of disease. Wastes that can cause health problems are human and animal feces, solid wastes, domestic...

and medical care are sometimes considered as part of the necessary infrastructure.

As population density

Population density

Population density is a measurement of population per unit area or unit volume. It is frequently applied to living organisms, and particularly to humans. It is a key term used in geography....

increases, birth rate

Birth rate

Crude birth rate is the nativity or childbirths per 1,000 people per year.According to the United Nations' World Population Prospects: The 2008 Revision Population Database, crude birth rate is the Number of births over a given period divided by the person-years lived by the population over that...

often increases and death rate typically decreases. The difference between the birth rate and the death rate is the "natural increase". The carrying capacity could support a positive natural increase, or could require a negative natural increase. Thus, the carrying capacity is the number of individuals an environment can support without significant negative impacts to the given organism and its environment. Below carrying capacity, populations typically increase, while above, they typically decrease. A factor that keeps population size at equilibrium is known as a regulating factor. Population size decreases above carrying capacity due to a range of factors depending on the species

Species

In biology, a species is:* a taxonomic rank or* a unit at that rank ....

concerned, but can include insufficient space, food supply

Food security

Food security refers to the availability of food and one's access to it. A household is considered food secure when its occupants do not live in hunger or fear of starvation. According to the World Resources Institute, global per capita food production has been increasing substantially for the past...

, or sunlight

Sunlight

Sunlight, in the broad sense, is the total spectrum of the electromagnetic radiation given off by the Sun. On Earth, sunlight is filtered through the atmosphere, and the solar radiation is obvious as daylight when the Sun is above the horizon. Near the poles in summer, the days are longer and the...

. The carrying capacity of an environment may vary for different species and may change over time due to a variety of factors, including: food availability, water supply

Water supply

Water supply is the process of self-provision or provision by third parties in the water industry, commonly a public utility, of water resources of various qualities to different users. Irrigation is covered separately.- Global access to water:...

, environmental conditions and living space.

The term "carrying capacity" comes from its use in the shipping

Shipping

Shipping has multiple meanings. It can be a physical process of transporting goods and cargo, by land, air, and sea. It also can describe the movement of objects by ship.Land or "ground" shipping can be by train or by truck...

industry to describe freight capacity, and a recent review finds the first use of the term in an 1845 report by the US Secretary of State to the Senate (Sayre, 2007).

Temporary exceptions

It is possible for a species to exceed its carrying capacity temporarily. Population variance occurs as part of the natural selection

Natural selection

Natural selection is the process by which heritable traits that make it more likely for an organism to survive and successfully reproduce become more common in a population over successive generations...

process but may occur more dramatically in some instances. Due to a variety of factors, one determinant of carrying capacity may lag behind another. For example, a waste

Waste

Waste is unwanted or unusable material.In living organisms, waste is the unwanted substances or toxins that are expelled from them. More commonly, waste refers to the materials that are disposed of in a system of waste management.Waste is directly linked to human development, both technologically...

product of a species may build up to toxic levels slower than the food supply is exhausted. The result is a fluctuation in the population around the equilibrium point which is statistically significant. These fluctuations are increases or decreases in the population until either the population returns to the original equilibrium

Equilibrium

Equilibrium is the condition of a system in which competing influences are balanced and it may refer to:-Mathematics:* The stationary point of a dynamical system is often called an123 equilibrium....

point, or a new equilibrium is established. These fluctuations may be more devastating for an ecosystem

Ecosystem

An ecosystem is a system of interdependent organisms which share the same habitat, in an area functioning together with all of the physical factors of the environment. Ecosystems can be permanent or temporary. Ecosystems usually form a number of food webs...

than are gradual population corrections, because if it produces drastic decreases or increases, this may affect other species in the ecosystem and they may begin to move with statistical significance around their own equilibrium points. The fear is of a domino-like effect, where the final consequences are unknown and may lead to collapses of species or even whole ecosystems.

Examples

One of the world's best-studied predator-prey relationships is the moose

Moose

The moose or common elk , , is the largest extant species in the deer family. Moose are distinguished by the palmate antlers of the males; other members of the family have antlers with a "twig-like" configuration....

and wolf population

Population

In biology, a population is the collection of inter-breeding organisms of a particular species; in sociology, a collection of human beings. Individuals within a population share a factor may be reduced by statistical means, but such a generalization may be too vague to imply anything...

of Isle Royale National Park

Isle Royale National Park

Isle Royale National Park is a U.S. National Park in the state of Michigan. Isle Royale, the largest island in Lake Superior, is over 45 miles in length and 9 miles wide at its widest point. The park is made of Isle Royale itself and approximately 400 smaller islands, along with any submerged...

http://www.isleroyalewolf.org/ in Lake Superior

Lake Superior

Lake Superior is the largest of the five Great Lakes of North America. It is bounded to the north by Ontario, Canada and Minnesota, United States, and to the south by the U.S. states of Wisconsin and Michigan...

. Without the wolves, the moose would overgraze the island's vegetation. Without the moose, the wolves would die. The first scientists who studied the issue thought that the wolves would eventually overpopulate and kill all the moose calves, then die from famine. But this has not occurred, and in fact the wolves appear to be "limiting their own population size".

Easter Island

Easter Island

Easter Island ; is a Polynesian island in the southeastern Pacific Ocean, at the southeastern most point of the Polynesian triangle. A special territory of Chile annexed in 1888, Easter Island is widely famous for its 887 extant monumental statues, called moai , created by the early Rapanui people...

has been cited as an example of a human population crash. When fewer than 100 humans first arrived, the island was covered with trees with a large variety of food types. In 1722, the island was visited by Jacob Roggeveen, who estimated a population of 2000 to 3000 inhabitants with very few trees, "a rich soil, good climate" and "all the county was under cultivation". Half a century later, it was described as "a poor land" and "largely uncultivated". The ecological

Ecology

Ecology is the interdisciplinary scientific study of the interactions between organisms and the interactions of these organisms with their environment....

collapse which followed has been variously attributed to overpopulation

Overpopulation

Overpopulation is a condition where an organism's numbers exceed the carrying capacity of its habitat. In common parlance, the term usually refers to the relationship between the human population and its environment, the Earth....

, slave traders

History of slavery

The history of slavery covers many different forms of human exploitation across many cultures throughout history. Slavery, generally defined, refers to a situation where one human being is considered to be the property of another, and is therefore obligated to perform tasks for their owner without...

, European diseases (including a smallpox

Smallpox

Smallpox is an infectious disease unique to humans, caused by either of two virus variants, Variola major and Variola minor. The disease is also known by the Latin names Variola or Variola vera, which is a derivative of the Latin varius, meaning spotted, or varus, meaning "pimple"...

epidemic

Epidemic

Defining an epidemic can be subjective, depending in part on what is "expected". An epidemic may be restricted to one locale , more general or even global...

which killed so many so quickly, the dead were left unburied and a tuberculosis

Tuberculosis

Tuberculosis is a common and often deadly infectious disease caused by mycobacteria...

epidemic which wiped out a quarter of the population), civil war

Civil war

A civil war is a war between organized groups within a single nation state, or, less commonly, between two nations created from a formerly-united nation state. The aim of one side may be to take control of the nation or a region, to achieve independence for a region, or to change government policies...

, cannibalism

Cannibalism

Cannibalism is the act or practice of humans eating the flesh of other humans.The word can be extended into zoology to mean any species consuming members of its own kind, and used outside of biological fields in a metaphorical sense: "Cannibalization" refers to the reuse of parts or ideas, such as...

and invasive species

Invasive species

'Invasive species' is a phrase with several definitions. The first definition expresses the phrase in terms of non-indigenous species that adversely affect the habitats they invade economically, environmentally or ecologically...

(such as the Polynesian rat

Polynesian Rat

The Polynesian Rat, or Pacific Rat , known to the Māori as kiore, is the third most widespread species of rat in the world behind the Brown Rat and Black Rat. The Polynesian Rat originates in Southeast Asia but, like its cousins, has become well travelled - infiltrating Fiji and most Polynesian...

s which may have wiped out the ground nesting bird

Bird

Birds are winged, bipedal, endothermic , vertebrate animals that lay eggs. There are around 10,000 living species, making them the most numerous tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Birds range in size from the Bee Hummingbird to the ...

s and eaten the palm tree seeds). Whatever the combination of factors, only 111 inhabitants were left on the island in 1877. For whatever reasons (whether Moai

Moai

Moai or mo‘ai are monolithic human figures carved from rock on the Polynesian island of Rapa Nui between the years 1250 and 1500. Nearly half are still at Rano Raraku, the main moai quarry, but hundreds were transported from there and set on stone platforms called ahu around the island's perimeter...

worship, survival, status or sheer ignorance), the question of how many humans the island could realistically support never seems to have been answered. This example, and others, are discussed at length in Jared Diamond

Jared Diamond

Jared Mason Diamond is an American scientist and nonfiction author whose work draws from a variety of fields. He is currently Professor of Geography and Physiology at UCLA...

's Collapse.

The Chincoteague Pony

Chincoteague Pony

The Chincoteague Pony is a hardy breed that developed on Assateague Island, which is off the Atlantic coast of Maryland and Virginia. The ponies live in a feral condition on the Virginia portion of Assateague and are owned and managed by the Chincoteague Volunteer Fire Company...

Swim http://www.kyhorsepark.com/imh/bw/chinco.html is a human-assisted example.

Both herds are managed differently. The National Park Service owns and manages the Maryland
Maryland
Maryland is a state located in the Mid Atlantic region of the United States, bordering Virginia, West Virginia and the District of Columbia to the south and west, Pennsylvania to the north, and Delaware to the east. It is comparable in size to the European country of Belgium. According to the U.S...

herd while the Chincoteague Volunteer Fire Company
Chincoteague Fire Department
The Chincoteague Fire Department is a historic U.S. building located at 4026/4028 Main Street, Chincoteague Island, Virginia. This building was initially constructed in 1930 and expanded in 1957...

owns and manages the Virginia herd. The Virginia herd, referred to as the "Chincoteague" ponies, is allowed to graze on Chincoteague National Wildlife Refuge
Chincoteague National Wildlife Refuge
The Chincoteague National Wildlife Refuge is a wildlife preserve operated by the U.S. Fish & Wildlife Service. It is primarily located on the Virginia side of Assateague Island with portions located on the Maryland side of the island as well as Morris Island and Wildcat Marsh...

, through a special use permit issued by the U.S. Fish and Wildlife Service. The size of both herds is restricted to approximately 150 adult animals each in order to protect the other natural resources of the wildlife refuge.

A further example is the Island of Tarawa

Tarawa Atoll

Tarawa is an atoll in the central Pacific Ocean, previously the capital of the former British colony of the Gilbert and Ellice Islands. It is the location of the capital of the Republic of Kiribati, South Tarawa...

, where the finite amount of space is evident, especially since landfills cannot be dug to dispose of solid waste, due to constraints in the subsurface rock and lack of topographic elevations. With colonial influence and an abundance of food (relative to life before the year 1850), the population has expanded to the extent that overpopulation

Overpopulation

is transparently present.

Mathematics

For a specific case example in the wild, see the Lotka-Volterra equation

Lotka-Volterra equation

The Lotka–Volterra equations, also known as the predator–prey equations, are a pair of first-order, non-linear, differential equations frequently used to describe the dynamics of biological systems in which two species interact, one a predator and one its prey. They were proposed...

, which shows how limited resources will cause the predator population to decline, due to famine. Note that depending on the situation, the impact of famine could be moderate (where the prey is not the main source of food for the predator), or extreme (where the prey becomes extinct due to over-predation, such as when humans hunted mammoth

Mammoth

A mammoth is any species of the extinct genus Mammuthus. These proboscideans are members of Elephantidae, the family of elephants and mammoths, and close relatives of modern elephants. They were often equipped with long curved tusks and, in northern species, a covering of long hair. They lived from...

populations to extinction; if the prey is the only source of food, the predator will also become extinct unless it can find another food source).

Humans

In the words of one researcher: "Over the past three decades, many scholars have offered detailed critiques of carrying capacity—particularly its formal application—by pointing out that the term does not successfully capture the multi-layered processes of the human-environment link, and that it often has a blame-the-victim

Victim blaming

Victim blaming is holding the victims of a crime, an accident, or any type of abusive maltreatment to be entirely or partially responsible for the unfortunate incident that has occurred in their life. Victim blaming is a typical fascist trait, infamously expressed in arguments like "a raped woman...

framework. These scholars most often cite the fluidity and non-equilibrium nature of this relationship, and the role of external forces in influencing environmental change, as key problems with the term."

In other words, the relationship of humans to their environment may be more complex than is the relationship of other species to theirs. Humans can alter the type and degree of their impact on their environment by, for instance, increasing the productivity of land through more intensive farming techniques, leaving a defined local area, or scaling back their consumption; of course, humans may also irreversibly decrease the productivity of the environment or increase consumption (see Overconsumption).

Supporters of the concept argue that humans, like every species, have a finite carrying capacity. Animal population size, living standards, and resource depletion vary, but the concept of carrying capacity still applies. The World3

World3

The World3 model was a computer simulation of interactions between population, industrial growth, food production and limits in the ecosystems of the Earth. It was originally produced and used by a Club of Rome study that produced the model and the book The Limits to Growth...

model of Donella Meadows

Donella Meadows

Donella "Dana" Meadows was a pioneering American environmental scientist, teacher and writer. She is best known as lead author of the influential book The Limits to Growth, which made headlines around the world.- Life :Born in Elgin, Illinois, Meadows was educated in science, receiving a B.A...

deals with carrying capacity at its core.

Carrying capacity, at its most basic level, is about organisms and food supply, where "X" amount of humans need "Y" amount of food to survive. If the humans neither gain or lose weight in the long run, the calculation is fairly accurate. If the quantity of food is invariably equal to the "Y" amount, carrying capacity has been reached. Humans, with the need to enhance their reproductive success (see Richard Dawkins' The Selfish Gene

The Selfish Gene

The Selfish Gene is a book on evolution by Richard Dawkins, published in 1976. It builds upon the principal theory of George C. Williams's first book Adaptation and Natural Selection...

), understand that food supply can vary and also that other factors in the environment can alter humans' need for food. A house, for example, might mean that one does not need to eat as much to stay warm as one otherwise would. Over time, monetary transactions have replaced barter and local production, and consequently modified local human carrying capacity. However, purchases also impact regions thousands of miles away. For example, carbon dioxide

Carbon dioxide

Carbon dioxide is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. It is a gas at standard temperature and pressure and exists in Earth's atmosphere in this state...

from an automobile

Automobile

An automobile, motor car or car is a wheeled motor vehicle used for transporting passengers, which also carries its own engine or motor...

travels to the upper atmosphere. This led Paul R. Ehrlich

Paul R. Ehrlich

Paul Ralph Ehrlich is an American entomologist specializing in Lepidoptera . He became a household name after publication of his 1968 book The Population Bomb, in which he wrongly predicted that mass starvation would occur during the 1970s and 1980s which could not be prevented even by immediate...

to develop the IPAT equation:Ehrlich and Holdren 1971

I = P * A * T

where:

I is the impact on the environment resulting from consumption

P is the population number

A is the consumption per capita (affluence)

T is the technology factor

This is another way of stating the carrying capacity equation for humans which substitutes impact for resource depletion, adding the technology term to cover different living standards. As can be seen from the equation, money affects carrying capacity - but it is too general a term for accurate carrying capacity calculation.

The concept of the "ecological footprint

Ecological footprint

The ecological footprint is a measure of human demand on the Earth's ecosystems. It compares human demand with planet Earth's ecological capacity to regenerate. It represents the amount of biologically productive land and sea area needed to regenerate the resources a human population consumes and...

" was developed to examine differential consumption by humans. By calculating the average consumption of humans over a small area, projections can be made for that type of population's impact on the environment.

Carrying capacity 'averages' the blame for these impacts by blaming the rich for using too many resources, as well as blaming the poor for being too numerous. Carrying capacity calculates the 'average' use of food and resources, which of course is closer to the billions of poor in the world than to the hundreds of billionaires.

This type of discussion raises the question of whether or not it is possible to define a measure of sustainability

Sustainability

Sustainability, in a broad sense, is the capacity to endure. In ecology, the word describes how biological systems remain diverse and productive over time...

which does not already contain implicit assumptions about solutions to the problems of resource over-exploitation and environmental degradation.

Possible reduction of Earth's carrying capacity in the 21st century

Agricultural capability on Earth expanded in the last quarter of the 20th century. But now there are many projections of a continuation of the decline in world agricultural capability (and hence carrying capacity) which began in the 1990s. Most conspicuously, China's food production is forecast to decline by 37% by the last half of the 21st century, placing a strain on the entire carrying capacity of the world, as China's population could expand to about 1.5 billion people by the year 2050. This reduction in China's agricultural capability (as in other world regions) is largely due to the world water crisis

Water crisis

Water crisis is a term that has been used by some to refer to the world’s water resources relative to human demand. The term has been applied to the worldwide water situation by the United Nations and other world organizations. Others, for example the Food and Agriculture Organization, claim there...

and especially due to mining groundwater

Groundwater

Groundwater is water located beneath the ground surface in soil pore spaces and in the fractures of lithologic formations. A unit of rock or an unconsolidated deposit is called an aquifer when it can yield a usable quantity of water. The depth at which soil pore spaces or fractures and voids in...

beyond sustainable yield, which has been happening in China since the mid-20th century.

Possible expansion

Not all social scientists and demographers are convinced of an imminent carrying capacity crisis for humans. The Danish economist Ester Boserup

Ester Böserup

Ester Boserup , born Ester Børgesen, was a Danish economist and writer. She studied economical and agricultural development, worked at the United Nations as well as other international organizations and she wrote several books...

has shown how technological developments in agriculture can increase carrying capacity, although not without limitations. Her work is summarized in the AAAS Population & Environment Atlas as follows:http://atlas.aaas.org/index.php?part=1&sec=theory

A more sophisticated adaptation approach was put forward by Ester Boserup in her classic book The Conditions of Agricultural Growth. Boserup suggested that population growth was the principal force driving societies to find new agricultural technologies (Boserup, The Conditions of Agricultural Growth, Allen and Unwin, 1965, expanded and updated in Population and Technology, Blackwell, 1980.).

Unlike Julian Simon
Julian Lincoln Simon
Julian Lincoln Simon was a professor of business administration at the University of Maryland and a Senior Fellow at the Cato Institute at the time of his death, after previously serving as a longtime business professor at the University of Illinois at Urbana-Champaign.Simon wrote many books and...

, Boserup did not claim that the process ran smoothly. She acknowledged that population pressure could cause serious resource shortages and environmental problems, and it was these problems that drove people to find solutions. Nor did she claim that things were always better after the adaptation.

They could often be worse. For example, when hunter-gatherers with growing populations depleted the stocks of game and wild foods across the Near East
Near East
Near East today is an ambiguous term that covers different countries for archeologists and historians, on one hand, and for political scientists, economists, and journalists, on the other...

, they were forced to introduce agriculture. But agriculture brought much longer hours of work and a less rich diet than hunter-gatherers enjoyed. Further population growth among shifting slash-and-burn farmers led to shorter fallow periods, falling yields and soil erosion. Plowing and fertilizers were introduced to deal with these problems - but once again involved longer hours of work and degradation of soil resources(Boserup, The Conditions of Agricultural Growth, Allen and Unwin, 1965, expanded and updated in Population and Technology, Blackwell, 1980.).

If agricultural innovation could increase with population density

Population density

Population density is a measurement of population per unit area or unit volume. It is frequently applied to living organisms, and particularly to humans. It is a key term used in geography....

, carrying capacity might also increase in some areas, averting a crisis there. This hypothesis might find support in the work of Mike Mortimore and Mary Tiffen (1994) http://www.drylandsresearch.org.uk/dr_summary.html) in high-density East Africa

East Africa

East Africa or Eastern Africa is the easterly region of the African continent, variably defined by geography or geopolitics. In the UN scheme of geographic regions, 19 territories constitute Eastern Africa:...

, and in several other studies which they and others have conducted across the continent. However, Africa is still subject to desertification

Desertification

Desertification is the degradation of land in arid and dry sub-humid areas, resulting primarily from man-made activities and influenced by climatic variations...

and other such effects which suggest that population may be outpacing agricultural development.

In tourism

The process of defining Tourism Carrying Capacity (TCC) is composed of two parts. It follows (in principle) the conceptual framework for TCC as described by Shelby and Heberlein (1986), and these parts are described as follows:

Descriptive part (A): Describes how the system (tourist destination) under study works, including physical, ecological, social, political and economic aspects of tourist development. Within this context of particular importance is the identification of:

Constraints: limiting factors that cannot be easily managed. They are inflexible, in the sense that the application of organisational, planning, and management approaches, or the development of appropriate infrastructure does not alter the thresholds associated with such constraints.
Bottleneck
Bottleneck
A bottleneck is a phenomenon where the performance or capacity of an entire system is limited by a single or limited number of components or resources. The term bottleneck is taken from the 'assets are water' metaphor. As water is poured out of a bottle, the rate of outflow is limited by the width...

s: limiting factors of the system which managers can manipulate (number of visitors at a particular place).
Impacts: elements of the system affected by the intensity and type of use. The type of impact determines the type of capacity (ecological-physical, social, etc). Emphasis should be placed on significant impacts.

Evaluative part (B): Describes how an area should be managed and the level of acceptable environmental impacts. This part of the process starts with the identification (if it does not already exist) of the desirable condition or preferable type of development. Within this context, goals and management objectives need to be defined, alternative fields of actions evaluated and a strategy for tourist development formulated. On the basis of this, Tourism Carrying Capacity can be defined. Within this context, of particular importance is the identification of:

Goals and/or objectives: (i.e. to define the type of experience or other outcomes which a recreational setting should provide).

Differing definitions

First of all, the carrying capacity can be the motivation to attract tourists visit the destination. The tourism industry, especially in national parks and protected areas, is subject to the concept of carrying capacity so as to determine the scale of tourist activities which can be sustained at specific times in different places. Various scholar over the years have developed several arguments developed about the definition of carrying capacity. Middleton and Hawkins defined carrying capacity as a measure of the tolerance of a site or building which is open to tourist activities, and the limit beyond which an area may suffer from the adverse impacts of tourism (Middleton & Hawkins, 1998). Chamberlain defined it as the level of human activity which an area can accommodate without either it deteriorating, the resident community being adversely affected or the quality of visitors' experience declining (Chamberlain, 1997). Clark defined carrying capacity as a certain threshold (level) of tourism activity, beyond which there will be damage to the environment and its natural inhabitants (Clark, 1997).

The World Tourism Organisation argues that carrying capacity is the maximum number of people who may visit a tourist destination at the same time, without causing destruction of the physical, economic and socio-cultural environment and/or an unacceptable decrease in the quality of visitors' satisfaction (http://ec.europa.eu/environment/iczm/pdf/tcca_material.pdf. Date assessed 08/03/07). In the publication, ‘Agenda 21 for the Travel and Tourism Venture: towards environmentally sustainable development’, the Secretary-General of the World Tourism Organization.

As part of a planning system

The definitions of carrying capacity need to be considered as processes within a planning process for tourism development which involves:

Setting capacity limits for sustaining tourism activities in an area. This involves a vision about local development & decisions about managing tourism.
Overall measuring of tourism carrying capacity does not have to lead to a single number, like the number of visitors (http://ec.europa.eu/environment/iczm/pdf/tcca_material.pdf. Date assessed 08/03/07).
In addition, carrying capacity may contain various limits in respect to the three components (physical-ecological, socio-demographic and political–economic).

“Carrying capacity is not just a scientific concept or formula of obtaining a number beyond which development should cease, but a process where the eventual limits must be considered as guidance. They should be carefully assessed and monitored, complemented with other standards, etc. Carrying capacity is not fixed. It develops with time and the growth of tourism and can be affected by management techniques and controls” (Saveriades, 2000).

The reason for considering carrying capacity as a process, rather than a means of protection of various areas is in spite of the fact that carrying capacity was once a guiding concept in recreation and tourism management literature. Because of its conceptual elusiveness, lack of management utility and inconsistent effectiveness in minimising visitors' impacts, carrying capacity has been largely re-conceptualized into management by objectives approaches, namely: the limits of acceptable change (LAC), and the visitor experience and resource protection (VERP) as the two planning and management decision-making processes based on the new understanding of carrying capacity (Lindberg and McCool, 1998). These two have been deemed more appropriate in the tourism planning processes of protected areas, especially in the United States, and have over the years been adapted and modified for use in sustainable tourism and ecotourism contexts (Wallace, 1993; McCool, 1994; Harroun and Boo, 1995).