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Carrying
capacity in ecology refers to the level of land or resource use both by humans or animals,
that can be sustained over the long term by the natural regenerative power of the
environment.
Current growth and consumption patterns are placing increasing
stress on ecosystems. Environmental degradation, biodiversity loss, deforestation, and the
breakdown of social and economic systems are a few of the signs which indicate that
ecosystems are stressed.
Carrying capacity assumes that there are a finite number of people who can be supported
without degrading the natural environment and social, economic and cultural systems and,
as such, "is an indirect measure of the maximum level of stress that the ecosystem
can maintain". ( Barbier, Burgess and Folke 1994).
Carrying capacity models should not use fixed prey density thresholds: a plea for using
more tools of behavioural ecology
Jan A. van Gils , Pim Edelaar , Graciela Escudero and Theunis Piersma
Earlier studies have developed models of carrying capacity to predict the number of
animals a certain area can support. These models assume that resources are not renewed
after consumption ('standing stock' models), and that the initial number of prey and the
rate of prey consumption determine the time a population of foragers can live in an area.
Within such areas, foragers give up feeding at a sub-site or patch when intake rates no
longer cover energy expenditure. To improve the success rate of the models' predictions,
we here change the existing rate-maximising models into fitness-maximising models, and
include dynamics in the availability of patches. These new (conceptual) models show that
the approaches used so far may over- as well as underestimate carrying capacity. We review
empirical studies that have aimed to estimate carrying capacity, and discuss how concepts
have been confused. We make explicit suggestions on how to proceed in predicting carrying
capacities in future studies. - blackwell-synergy.com
Subsistence ecology and carrying capacity in two Papua New Guinea populations. -
Ohtsuka R, Department of Human Ecology, University of Tokyo, Japan.- J Biosoc Sci. 1994
Jul;26(3):395-407
This article examines the mechanisms of subsistence adaptation of two Papua New Guinea
populations, the Metroxylon sago-depending lowland Gidra and the taro-monoculture Mountain
Ok, surviving in low population densities of 0.5 and 1.4 persons per km2. Observation of
the groups' land use systems strongly suggests that their population densities have not
been far below the carrying capacity, although the territory of each population is
markedly heterogeneous. Both groups have maintained their sustainable food production not
only for resource management but also for survival at a population level, either expanding
their territory or changing the sustainable level in tandem with changes of subsistence
system.
PIP: A study was undertaken among the Gidra-speaking population of a deltaic lowland and
the mountain Ok-speaking horticulturalists in the southeastern end of the Upper Murray
Valley in Papua New Guinea to determine whether or not their low population densities have
been far below the carrying capacities and, if not, how the people have coped with
environmental restrictions. The Gidra had a population of just under 2000 during the study
period (since 1971) in a territory of 4000 sq. km. They have villages on the coast, along
a river, and inland. The Gidra inhabitants of Wonie village are used for descriptions of
subsistence mechanisms with special attention to time-space aspects of their activities
and to food and nutrition. The 650 Ok (in 1985-86) live in 5 villages on a steep slope.
The Ok people of Selbang village are the subject of this paper because they have
maintained the traditional taro monoculture, and their subsistence strategies are useful
in assessing the Ok longterm adaptation. The description of the basic subsistence systems
of these groups is illustrated by tables showing the daily adult male intake of energy and
protein by Wonie villagers, derived from 8 categories of food; the distances between
horticultural gardens and the village settlement for Wonie villagers in 1971, 1981, and
1989; and the daily adult male intake of energy and protein in Selbang village in 1986,
derived from 7 categories of foods and by a figure showing the number of sago groves and
gardens in the Wonie village land on a meshed map with the village in the center for 1971,
1981, and 1989. This analysis suggests that the low population densities of these groups
has not been far below the optimum carrying capacity as determined for the Gidra by the
density of sago palm stands and for the Ok by the limited land area suitable for taro
gardens and the long fallow period involved in taro cultivation. It is suggested that a
human population's territory is heterogeneous in terms of carrying capacity when it is
synchronically observed. When survival is diachronically observed, increased population in
the core (more advantageous) environment is pushed to the fringe areas where human
adaptation advances must be made. Changing subsistence strategies to increase the carrying
capacity within the sustainable level of resource management may also occur. -
ncbi.nlm.nih.gov
Meta-analysis of intrinsic rates of increase and carrying capacity of populations
affected by toxic and other stressors.
Hendriks AJ, Maas-Diepeveen JL, Heugens EH, Van Straalen NM.
Department of Environmental Studies, Institute for Wetland and Water Research, Faculty of
Science, Radboud University Nijmegen, P.O. Box 9010, NL-6500 GL, Nijmegen, The
Netherlands. a.j.hendriks@science.ru.nl
Environ Toxicol Chem. 2005 Sep;24(9):2267-77.
Most of the thousands of substances and species that are of concern for environmental
management will not be investigated empirically at ecologically relevant levels because of
financial, practical, and ethical constraints. To allow risk assessment for these less
well-known categories, we have developed a mechanistic model with classical equations from
toxicology and ecology. The parameters are linked to well-known properties, such as the
octanol-water partition ratio K(ow), acute lethal (body) concentrations, and organism
size. This allows estimation of intrinsic rates of increase r and carrying capacity K over
a wide range of substances and species. The model was calibrated with parameter values
(micro +/- 95% confidence interval) obtained in reviews and validated by a meta-analysis
with largely independent data from 200 laboratory experiments. For single substances, the
5 to 95% interval of the observations on intrinsic rates of increase overlapped with the
range predicted by the model. Model and experiments independently indicated that
population growth ceased below 1% of the acute median lethal concentration in about 5% of
the cases. Exceptional values and possible explanations were identified. The reduction of
the carrying capacity K was nearly proportional to the inhibition of the population growth
r. Population-level effects of mixtures as estimated by concentration addition were
confirmed by observations in the experiments. The impact of a toxicant and another
stressor could generally be described by response multiplication, with the exception of
cases with extreme stress. Data sets on population laboratory experiments are biased to
metals and crustaceans. This field will benefit from empirical studies on chemicals,
conditions, and species, identified as risky by the model. Other implications of the model
for environmental management and research are discussed. - ncbi.nlm.nih.gov
Land Reform, Range Ecology, and Carrying Capacities in Namaqualand, South Africa
Authors: Benjaminsen, Tor A.; Rohde, Rick; Sjaastad, Espen; Wisborg, Poul; Lebert, Tom
Source: Annals of the Association of American Geographers, Volume 96, Number 3, September
2006, pp. 524-540(17)
Abstract: In South African rangeland management, there is a long history of using the
notion of carrying capacity as a central planning tool for environmental conservation and
agricultural modernization. Today, in the new South Africa, the “need” for
livestock keepers to adhere to a defined carrying capacity in order to conserve rangeland
resources and to achieve economic development remains an institutionalized
“fact.” In this article, we use interviews, livestock and rainfall data, policy
documents, and aerial photos to discuss the idea of carrying capacity as it is currently
used in the implementation of land reform in Namaqualand in the Northern Cape Province.
This article is a contribution at the interface of human ecology and political ecology,
linking environmental issues to economic constraints, land rights, social justice, and
values. Policymakers and extension services usually see carrying capacity as a purely
technical issue. We argue that this is problematic because it gives privilege to
environmental sustainability and to one particular perception of the ideal landscape at
the expense of livelihood security and poverty alleviation. It also perpetuates the
colonial myth that the private ranch system is an ideal one, independent of disparate
production goals and unequal economic opportunities and constraints, and it ignores
evidence going back more than half a century that the Namaqualand range is capable of
sustaining livestock densities far greater than those recommended. The winners that emerge
from the current policy focus on carrying capacity are the few emergent black commercial
farmers as well as conservationist interests; the losers are the majority of poor
stockowners in the communal areas. - ingentaconnect.com
Carrying capacity reconsidered: from Malthus' population theory to cultural carrying
capacity
Authors: Seidl I.; Tisdell C.A.
Source: Ecological Economics, Volume 31, Number 3, December 1999, pp. 395-408(14)
Abstract: In this paper the concept of carrying capacity is investigated to provide an
improved understanding about its contribution to solve environmental problems. Light is
shed on its form, interpretation and application in biology, demography, applied and human
ecology. The analysis begins with an examination of the bedrock of carrying capacity which
is Malthus’ population theory, and its mathematical formulation — the logistic
growth equation. The investigation shows Malthus’ thinking to be both political and
normative. Furthermore, the rigid assumptions of the logistic equation and the uncertainty
of its terms are found not to allow an unequivocal calculation and prediction of the upper
limits (carrying capacity) of population growth. It is illustrated that in ecology,
carrying capacity focuses on the quality of an ecosystem (pressures on it) and
corresponding population numbers, and less on equilibrium of populations as in biology. It
is shown that carrying capacity, when applied in fields where human activity or human aims
are involved, is a complex normative concept influenced by ecological dynamics, human
values and aims, institutional settings and management practices. However, it is
demonstrated that the discussion about institutional settings, aims, and values does not
take place as much as necessary for its useful application and operationalization in such
fields. Instead, authors fall back on sustainability, environmental standards or
resilience. The main contribution of carrying capacity in applied and human ecology is as
a political concept generally highlighting that exponential growth and thus environmental
pressures have to be curbed. Carrying capacity is far from being a universal constraint.
Operationalization will continue to be hampered as long as agreements are missing about
which social carrying capacity is to be opted for and when it is considered to have been
transgressed. - sciencedirect.com
A test of carrying capacity models with or without spatial and behavioural
ecology
Abstract: There is an urgent need for tools to predict the effects ofhabitat change on
wildlife. After earlier abandoning carryingcapacity as a useful concept, scientists now
agree that in the caseof migratory birds the carrying capacity of a non-breeding site
canbe meaningfully defined as the number of bird-days a site can support. Current models
of carrying capacity assume a single giving-up fooddensity (GUD), often equal to the food
density at which a bird canjust meet its daily energy requirement (i.e., the critical
density).More refined work however showed that there is considerable variationin GUDs
within a site. In theory, the lowest observed GUD as well asthe average of the GUDs may
differ from the critical density. Thismeans that the actual carrying capacity may greatly
deviate from theone calculated by a single GUD model. The challenge is to developmore
advanced and more accurate methods to calculate carryingcapacity that incorporate spatial
or behavioural aspects. Theproposed research will focus on within-site differences in GUDs
ofBewick's swans feeding on pondweed tubers in the Lauwersmeer(Netherlands). This study
system is a very suitable one for a test ofcarrying capacity models for many reasons. The
research will consistof a combination of field work, experiments and modelling.
Theobserved number of bird-days will be compared with the ones predictedby models
incorporating one or more of the factors thathypothetically affect the carrying capacity,
namely the spatialvariation in food density, food availability, and metabolic
costs,individual differences, the additional food loss due tokleptoparasitic ducks and the
quality of the preceding site (Estonia). -
onderzoekinformatie.nl/en/oi/nod/onderzoek/OND1308810/
Carrying capacity assessment for the Greek islands of Kalymnos, Kos and Rhodes
B. S. Tselentis, D. G. Prokopiou, Department of Maritime Studies, University of
Piraeus, Greece
M. Toanoglou, University of Surrey, UK
Abstract: Carrying capacity assessment has become an indispensable tool for formulating
policy and strategies in the tourist industry worldwide. It is well known that Greece
depends heavily on the tourist trade, as this has, in recent years, become the main
economic activity in many of the Greek islands. The transformation of local economies from
primary and secondary production to tertiary has, over the years, substantially altered
the business environment in which such an activity takes place. Many studies have shown
that the tourist product is a blend of ecological, social and economic sub-systems,
operable in the area of interest. For the Greek Islands, environment, both natural and man
made, plays a leading role in the sustainable development of the industry. It is the
purpose of this paper to apply the principles of carrying capacity assessment to three
Greek islands, differing in their tourist development, in an effort to highlight the
importance of such a tool in developing long-term sustainable policies for such
communities.
Introduction: The World Tourism Organisation (WTO) proposes the following definition of
carrying capacity: “The maximum number of people that may visit a tourist destination
at the same time, without causing destruction to the physical, economic, socio-cultural
environment and an unacceptable decrease in the quality of visitors’
satisfaction”.
Today, controlling tourist growth has become a central policy issue for the tourist trade
and it is noteworthy that carrying capacity assessment has become an important tool for
facilitating planning and developing policy in the industry. -
library.witpress.com/pages/PaperInfo.asp?PaperID=17064
Carrying capacity assessment of Slovene Istria for tourism
I. Jurincic Turistica, College of Tourism Portoroz, University of Primorska, Slovenia
Abstract: The method of carrying capacity assessment has been found to be a useful tool
for saturation prevention as well as for implementing sustainable tourism development
strategies in Slovene Istria. It has been found that sustainable tourism development
allows for variations in tourism development intensity in the region. The aim of
sustainable tourism development is a long-term optimal use of tourism resources without
negative impacts on the natural, social and economic environments.
The major constraints that will have to be considered if tourism development is to be
sustainable are: waste water collection and treatment, lack of car parks, road and rail
transport, sea water quality, potable water resources, solid waste disposal and
management, and last but not least the dissatisfaction of the local community and tourists
with tourism. The development of more accommodation facilities would not be reasonable
without investments in general infrastructure facilities. Measures for increasing carrying
capacity have also been suggested.
Introduction: Today the development of tourism demands careful planning. The environmental
impact of tourism is harmful and has frequently been uncoordinated with other users of the
land. Moreover, the fragility of the environment has been seldom taken into consideration.
Tourism development has been often led by individual investors who put profitability in
the first place. To make the situation worse, this has been repeatedly done with complete
disregard for tourism development. -
library.witpress.com/pdfs/abstracts/SPD05/SPD05071AU1.pdf
Assessing the Carrying Capacity of the Florida Keys
Journal Population & Environment
Issue Volume 23, Number 4 / March, 2002
Alice L. Clarke, Florida International University, 11200 SW 8th Street, Miami, FL,
33199
Abstract In 1996, the State of Florida mandated a study of the Florida Keys, the most
populated portion of Monroe County, explicitly calling for a carrying capacity analysis to
function as a basis for determining building permit allocation in the future. The Florida
Keys Carrying Capacity Study, conducted by the State of Florida and the US Army Corps of
Engineers, has encountered challenges in trying to convert the vague carrying capacity
concept into a functional, quantitative method. Difficulties in responding to external
peer review advice suggests that institutional constraints are hindering re-direction of
the study. - springerlink.com/content/nf5thg5jbbb7q8qy/
Minimum requirements for modelling bivalve carrying capacity
Journal Aquatic Ecology
Issue Volume 31, Number 4 / December, 1997
A.C. Smaal, Centre for Shellfish Research, Netherlands Institute for Fisheries
Research/RIVO-DLO, P.O. Box 77, 4400 AB Yerseke, The Netherlands
T.C. Prins, National Institute for Coastal and Marine Management/RIKZ, P.O. Box 8039, 4330
EA Middelburg, The Netherlands
N. Dankers, Institute for Nature and Forestry Research/IBN-DLO, P.O. Box 167, 1790 AD Den
Burg, The Netherlands
B. Ball, The Martin Ryan Marine Science Institute, National University of Ireland, Galway,
Ireland
Abstract The concept of carrying capacity of an ecosystem fornatural populations is
derived from the logisticgrowth curve in population ecology, and defined as themaximum
standing stock that can be supported by agiven ecosystem for a given time. This
definitionneeds to be modified for the exploitation ofecosystems. Carrying capacity for
exploitation isdefined as the standing stock at which the annualproduction of a marketable
cohort is maximized. Forbivalve suspension feeders, the dominant factordetermining the
exploitation carrying capacity at theecosystem scale is primary production. At a
localscale carrying capacity depends on physicalconstraints such as substrate, shelter and
food supplyby tidal currents.We evaluate critically some existing models ofexploited
ecosystems for shellfish cultivation inorder to formulate the minimum requirements of
ageneric carrying capacity model. Generic models canbe developed for both the ecosystem
scale and thelocal scale, depending on the aim of the modelling.Transport processes,
sediment dynamics and submodelsfor organism and population level processes areminimum
requirements for carrying capacity modelling. - springerlink.com/content/u13q542668146589/
"Sizing the earth: recognition of economic carrying capacity."- Wetzel,
Kurt R. and John F. Wetzel. - Ecological Economics 12 (January 1995): 13-21.
Abstract: Argues that the biophysical properties of a finite earth and the realities of
economic transformation determine the economic carrying capacity of our planet. Economic
carrying capacity takes the form of maximum global economic welfare derivable from the
sustainable throughput flows of the ecosphere. This is fleshed out by development of a
welfare return curve plotted as a function of economic scale; the latter is measured by
entropic throughtput. The economic-ecological connection is made by employing the
Ehrlichs' equation, PAT=Impact, as the dual entity being measured on the abscissa. This
curve shows an initial acceleration which eventually flattens, reaches a maximum (carrying
capacity) and is followed by declining welfare. The shape of this curve is determined by
the rising costs associated with the ecosystemic impact of increasing throughput rates as
required by a growing economy. The primary thrust of the argument is that not only are
economic scales that exceed throughtput sustainability definitionally impossible to
maintain in the long run, but because of declining welfare, they are not even desirable in
the short run. Historical movement along this curve is discussed, relfecting growth in the
global economy. An analysis of rising impact costs and the serious mistake of advocating
growth to meet these costs is given, employing the notion of a social trap. Also
investigated are several additional causes and likely results of pending economic
overshoot. Among these are inter-generational penalties of reduced welfare potential from
a planet degraded by economic overgrowth. Several overshoot avoidance prescriptions are
offered as well as a discussion of stasis and contraction.
Human Ecology for Introductory Biology Courses: An Overview
PAUL R. EHRLICH, Department of Biological Sciences, Stanford University Stanford,
California 94305
Human ecology, specifically the population—resource—environment dilemma, should
be given thorough coverage in every introductory biology course. To aid educators in
integrating it into the course, the subject is outlined here and suggestions are given on
what topics should be emphasized and how they might be introduced to students. Special
attention is given to the fundamental role of population growth in the dilemma, and to the
complex interactions among population growth, depletion of resources, and environmental
deterioration. Today's human population size appears to be above the long-term carrying
capacity of Earth, and is only maintained (albeit often badly) by the exploitation of a
"one-time bonanza" of fertile soils, fossil fuels, concentrated ores, ground
water, and other species of organisms. If current trends continue, the depletion of these
resources will progressively degrade the human environment, destroying the capacity
ofnatural ecosystems to supply civilization with indispensible services. The results will
be in increasing frequency and severity of disasters, especially famines, that will at
first most seriously affect the poor. But the rich will increasingly be impoverished, and
be engulfed also. The basic solution to the dilemma is reduction of the size of the human
population to one well below the long-term carrying capacity (one living on resource
"income" rather than "capital") and establishing an equitable society
with a sustainable economic system. - icb.oxfordjournals.org/cgi/content/abstract/25/2/379
CARRYING CAPACITY AND PRE-DECLINE ABUNDANCE OF SEA OTTERS (ENHYDRA LUTRIS KENYONI) IN THE
ALEUTIAN ISLANDS
Douglas M Burn, Angela M Doroff, US Fish and Wildlife Service, Marine Mammals Management
Office, 1011 East Tudor Road, Anchorage, AK 99503 USA; Douglas_Burn@fws.gov
M Tim Tinker, Department of Ecology and Evolutionary Biology, Center for Ocean Health,
Long Marine Laboratory, University of California, Santa Cruz, CA 95064 USA - Northwestern
Naturalist: Vol. 84, No. 3, pp. 145–148.
Brown, Lester R. and Hal Kane. Full house : reassessing the Earth's population carrying
capacity. Worldwatch Environmental Alert series. New York: Norton & Company, 1994. 261
p.
Daily, G.C. and P.R. Ehrlich. "Population, sustainability, and Earth's carrying
capacity: a framework for estimating population sizes and lifestyles that could be
sustained without undermining future generations." BioScience 42: 761-71.
Kessler, J.J. "Usefulness of the human carrying capacity concept in assessing
ecological sustainability of land-use in semi-arid regions". Agriculture, Ecosystems
and Environment 48(1994) : 273-284.
McConnell, Robert L. "The human population carrying capacity of the Chesapeake Bay
Watershed : a preliminary analysis." Population and Environment : a journal of
interndisciplinary studies 16 (March 1995): 335-351.
Mwalyosi, R.B.B. "Population growth, carrying capacity and sustainable development in
Southwest Masailand." Journal of Environmental Management 33, no. 2: 175-187.
Rees, William E. " Ecological footprints and appropriated carrying capacity : what
urban economics leaves out. " Environment and urbanization 4(1992): 121-129.
van den Bergh and C.J.M. Jeroen. " A framework for modelling
economy-environment-development relationships based on dynamic carrying capacity and
sustainable development feedback." Environmental and Resource Economics 3 :
395-412.
Wackernagel, Mathis and William E. Rees. How big is our ecological footprint : a handbook
for estimating a community's appropriated carrying capacity : discussion draft. Vancouver:
UBC Department of Family Practice, 1993. 106 p.
Contents: Ecological sustainability; Calculating the appropriated carrying capacity of
households and municipalities; Data sources for assessing the appropriated caarrying
capacity of an average Canadian citizen; Tables and figures rlating to ACC analyses
Abstract: Provides the background and technical data for executing rough Appropriated
Carrying Capacity (ACC) estimates, with a particular focus on municipalities
Wackernagel, Mathis. How big is our ecological footprint? Using the concept of
appropriated carrying capacity for measuring sustainability. Vancouver: University of
British Columbia Task Force on Planning Healthy and Sustainable Communities, 1993. 8
p.
Western, S. "Carrying capacity, population growth, and sustainable development: a
case study from the Philippines." Journal of Environmental Management 27, no. 4:
364-367. |
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