Relationship between population size, carrying capacity, and limiting factors is described below.
Explanation:
1. There are four variables which govern changes in population size.
- births
- deaths
- immigration
- emigration
A population gains individuals by birth and immigration and loses individuals by death and emigration.
2. Populations vary in their capacity to grow. The maximum rate at which a population can increase when resources are unlimited and environmental conditions are ideal is termed the population's biotic potential.
3. There are always limits to population growth in nature. Populations cannot grow exponentially indefinitely. Exploding populations always reach a size limit imposed by the shortage of one or more factors such as water, space, and nutrients or by adverse conditions such as disease, drought and temperature extremes.
4. The factors which act jointly to limit a population's growth are termed the environmental resistance. The interplay of biotic potential and density-dependent environmental resistance keeps a population in balance.
5. Carrying Capacity
For a given region, carrying capacity is the maximum number of individuals of a given species that an area's resources can sustain indefinitely without significantly depleting or degrading those resources. Determining the carrying capacities for most organisms is fairly straightforward. For humans carrying capacity is much more complicated. The definition is expanded to include not degrading our cultural and social environments and not harming the physical environment in ways that would adversely affect future generations.
6. Population Impact
Homo sapiens is a species possessing a diversity of individual needs. Thus, sub-populations will have different requirements and different impacts on the environment. For example 100 million vegetarians will have a significantly different environmental impact than 100 million meat-eaters. This can be demonstrated by comparing the affect on water supplies by both sub-populations. About 1000 tons of water are needed to produce 1 ton of grain. Almost 40% of all grain is used in meat and poultry production. Add to this the amount of water that goes into the production of meat, and you can see that meat comsumption places more stress on global water supplies than grain consumption.
