Population dynamics is a branch of ecology that studies periodic and non-periodic changes in the number of different species, sex and age composition of the population, establishes the causes of these changes as a result of abiotic (not depending on the number and density of the population) and biotic (depending on the number and density of the population) environmental factors. Population dynamics, the totality of changes in the structural elements of the population in the ratio of fertility and mortality in it.

There are three types of population dynamics: stable (change in population size by several times); variable (fluctuations in population size by tens of times); explosive (periodic excess of the average size by hundreds or thousands of times).