Population studies & factors affecting the population.


Population is defined as the total number of organism of the same species living together in a given area at a particular time.

In an ecosystem, the community is made of many populations of different species. In population studies of a habitat, the following are usually studies:

1. Types of organism: this involves the listing of the various types of population that are founds in the particular habitat it help to determine the relationships that exist between the various organism (plant and animals) in a habitat.

2. Dominance: Dominance refers to these species that exert greater influence or a major controlling effect on the other members of the community. They relative importance of a species in the community is expected by dominance.

Dominance could be expresses in term of

  • Their number.
  • Occupation or largest portion of space.
  • Possession of the highest biomes.
  • The largest contribution to the energy flow in the habitat.

Or a species to be dominated in a habitat, it should possess some of these attribution over other species.

3. Population Characteristic: these characteristics include:

  • Population Size: this refers to the total number of the species of the same kind in a given area or habitat. A large population stands a better chance of surviving dangerous and unfavorable condition such as fire, Disease e.t.c while a small population can easily be wiped out.
  • Population Density: population density is defined as the numbe4r of individual organism per unit area or volume of the habitat. Mathematically, population density = Total Population or Population Size /Area of Habitat

Population density can be used to estimate the total number of individuals of a population or population size.

Mathematically, population size = Population Density x Area of Habitat.

  • Population Frequency: this refers to the number of times an organism occurs within a given area of a habitat.
  • Percentage Growth: this refers to the area or space covered or occupied by a given species in its habitat and it is expressed in percentage.
  • Population Growth Rate: this refers to the net result of the influence of natality (Birth Rate) and mortality (Death Rate) of organism in a given habitat.


1. Natality (Birth rate).

2. Mortality (Death rate).

3. Immigration (Dispersal).

4. Emigration.

5. Availability of food.

6. Seasonal Climatic Change.

7. Breeding Period.

8. Natural Disasters.


The population size or total population and population density of a particular in a terrestrial habitat can be estimated by the following procedures:

1. Choose and locate the same plot.

2. Then identify the species in the plot.

3. Measure the area with a measuring tape to know the area of the habitat.

4. Throw or toss the quadrate randomly at intervals for up to 10 or above times.

5. After each throw or toss, the number of species within the area of quadrate is recorded.

6. The density of species is calculated by dividing the average number of times the species occurs within the quadrant by the area of quadrant:

  • Frequent of species = x/y
  • Number of tosses = 10
  • Average number of species per quadrant = x/y = z
  • Area of quadrant = 1m2 (e) Density = z/Area of quadrant


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