Ecology Flashcards
(27 cards)
Ecology
The study of interactions among organisms and their environment
Size
Number of individuals living in an area. Determined by BR and DR
Density
Measurement of population per unit area. Affected by immigration and emigration
Dispersion
Spread of population, can be clustered, random or uniform
Biotic potential
In pop ecology, the natural reproductive potential of species. This has evolved through time and is related to survival rates. Mammals tend to have a smaller number of off spring as their rate of ‘survivorship’ is high, although they can be vulnerable to increase DR.
Environmental resistance
Term used to explain mortality rates controlled by environmental factors that prevent survival.
Density independent
(Increase death rate whatever pop size)Natural disasters are an example of density independent environmental limiting factor as they will increase the DR whatever the pop size
Density dependent
(Depends how many people are in an area) Such as food supply/disease will become more prevalent limiting growth as pop size/density increases.
Biotic
Living factors e.g. parasites
Abiotic
Non-living factors e.g. food/water
Exponential growth
Rapid/unrestricted growth
Logistic growth
Reach potential then growth rate slows
How has humanity grown through exponential phase
Human pop has overcome much of environmental resistance that was limiting growth- In past 200 years we have been through a log phase of exponential growth through development and technology
Lag phase (graph)
There is a high BR/DR with low life expectancy so replacement rate is consistent
Exponential phase (graph)
Improvements in technology, food supplies and medical care which reduce disease and overcome environ resistance
Stationary phase (graph)
There is more family planning, lower infant mortality and improved contraception
Overpopulation characteristics
Low income per capita/poverty Unemployment Outward migration Insufficient food/energy resources Prone to natural disasters War/conflict
Underpopulation characteristics
High income per capita Low unemployment Inward migration Good living conditions High levels of tech
Overpopulation
Too many people in an area relative to available resources. This reduces standard of living, so with no technology advances only a fall in pop will raise living standards
Underpopulation
Too few people to use the resources efficiently for a given level of tech. Suggests an increase in pop would mean a more effective use of resources/increased standard living for all
Optimum population
Ideal balance between population/resources. Pop size in a given area which working with all resources will give the highest standard of living for those living there. Maximising income per capita and is a balance that nations will try to achieve through direct/indirect management
Carrying capacity
Max pop size that an area/environment can sustain indefinitely- flexible depending on averg lifestyle
Ecological footprint
A measure of the demand placed by humans on Earths natural resources
Overshoot
An ecological term referring to a point when the population and its associated consumption of resources exceed the long term carrying capacity of the environment
