AQA Geography - Principles of population ecology and their application to human populations

Population growth dynamics. Concepts of overpopulation, underpopulation and optimum population. Implications of population size and structure for the balance between population and resources; the concepts of ‘carrying capacity’ and ‘ecological footprint’ and their implications.

Population, resources and pollution model: positive and negative feedback. Contrasting perspectives on population growth and its implications; Malthusian, neo-Malthusian and alternatives such as associated with Boserup and Simon.

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Ecology
The study of interactions among organisms and their environment. It is the study of how the population sizes of species change over time and space.
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Population
All the individuals of a species that live together in an area
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What are the three key features of populations?
The three key features of populations are size, density and dispersion.
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Size
number of individuals in an area. Determined by BR and DR
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Density
: measurement of population per unit area or unit volume. Affected by immigration, emigration, density-dependent factors (e.g. disease and competition) and density-independent factors (temperature and weather for example)
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Dispersion
spread of population. Can be clustered, random or uniform
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DENSITY DEPENDENT
the carrying capacity of a population
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DENSITY DEPENDENT factors
The density dependent factors are factors whose effects on the size or growth of the population vary with the population density. There are many types of density dependent limiting factors such as; availability of food, predation, disease, migration
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DENSITY INDEPENDENT
Events that limit the size of a population.  Most density-independent factors are abiotic, or nonliving. Some commonly used examples include temperature, floods, and pollution.
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OPTIMUM POPULATION
The number of people that can make the best use of all available resources within a country or region, ensuring that everyone has an adequate quality of life.
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OVER POPULATION
Too many people for the resources technology available.
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UNDER POPULATION
The population is too small and cannot fully utilise the resources available. Quality of life can only slowly be improved. An increase in population would lead to an increase in quality of life.
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CARRYING CAPACITY
The maximum population size that an area or environment can sustain indefinitely
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ECOLOGICAL FOOTPRINT
The impact of a person or community on the environment, expressed as the amount of land required to sustain their use of natural resources and the waste generated.
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Models describe two kinds of population growth...
EXPONENTIAL GROWTH has no upper limit and populations grow very quickly. LOGISTIC GROWTH has a limit and growth gets smaller and smaller as population size approaches a max
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carrying capacity
a maximum population imposed by limited resources in the environment
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Exponential growth produces?
J-shaped curve
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logistic growth produces?
S-shaped curve
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Positive feedback
enhances or amplifies changes – moving a system away from its equilibrium state and making it more unstable
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Negative feedback
is an opposing force which counters any change, holding the system in a more stable equilibrium
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Thomas Robert Malthus argued that population was held within resource limits by which two types of checks?
positive ones, which raised the death rate, and preventative ones, which lowered the birth rate. The positive checks included hunger, disease and war; the preventative checks, abortion, birth control, prostitution, homosexuality, postponement of marr
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Other cards in this set

Card 2

Front

Population

Back

All the individuals of a species that live together in an area

Card 3

Front

What are the three key features of populations?

Back

Preview of the front of card 3

Card 4

Front

Size

Back

Preview of the front of card 4

Card 5

Front

Density

Back

Preview of the front of card 5
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