CARRYING CAPACITY

Sociologyindex, Sociology of Environment. Environmental Movement, Sociology Books 2009

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.

Carrying capacity in ecology