(ii) Environmental resistance. The factors such as shortage of food, disease, predation, environmental natural calamities which impose a check on population size constitute environmental resistance. Environmental resistance decreases the rate of population growth.

(iii) Carrying capacity. It is a measure of the feeding capacity of an environment or ecosystem for a population of a species under a given set of conditions. If the population reaches its carrying capacity then the no further growth of the pooulation takes place.