1. ‘S’ – Shaped Growth or Sigmoid growth curve:
It is also called a sigmoid curve.
It has 3 phases:
1. Early or Lag phase: There is little or no growth.
2. Middle or Log or Exponential phase: There is fast growth in the population.
3. Stationary or Zero or Plateau phase:
- The population growth is zero.
- Mortality and natality are equal.
- The population becomes equal to the environmental carrying capacity.
In S (sigmoid) form, the population increases slowly at first, then more rapidly but it soon slows down gradually as the environment resistance increases.
Factors affecting Population Growth:
- The population of any country is effected by 4 factors
- Age Distribution
- More natality in any country and less mortality increases population and the vice versa. Similarly, if human Immigration is more than migration, the population will increase and vice versa.