(a) In the given equation, N is the population density at time f and its density at time t + 1 is
Nt + 1 = Nt + [(B + I) - (D + E)]
The above equation shows that population density which increases if the number of births plus the number of immigrants (B + I) is more than the number of deaths, plus the number of emigrants (D + E), otherwise it will decrease. Under normal conditions, births and deaths are the most important factors. The other two factors are important only under special conditions. For instance, if a new habitat is just being colonized, immigration may contribute more significantly to population growth than birth rates.
(b) Population density of a species is the number of individuals of a species per unit area or volume. e.g., number of animals per square kilometer, number of trees per hectare, number of phytoplanktons per cubic liter of water.
Population density (PD) can be calculated as
P.D. = N/*
where,
N = Number of individuals in a region.
- = Number of unit areas in a region.
Population of an area is described on the basis of three parameters.
a = Number and kind of individuals of a species.
b = A given space or an area.
c = Time.
Population density reflects the success of a species in a given area.
