Population is defined as the total number of organisms of the same species living together in a given area at a particular time in an ecosystem, the community is made up of many populations of different species.

### Factors Affecting Population

- Birth rate
- Mortality (death rate)
- Immigration
- Availability of food
- Seasonal climatic changes
- Breeding periods
- Natural disasters examples earthquake, volcano etc.

## Population Studies By Sampling

## Population Size

**A QUADRANT SAMPLING METHOD :**

Choose and locate sample plot and identify the plant species in the plot measure the area using a measuring tape to know the area of the habitat throw or toss the quadrant randomly at intervals for up to 10 times or above. After each throw or toss record the number in area of quadrant, the total number of each species obtained from several throws (10times) divided by the number of the species per quadrant. The average when multiplied by the total area of the habitat and then divided by the area of quadrant gives the population size of the species.

Population density X Area of habitat habitat = p size.

#### POPULATION DENSITY

Numbers of toss or throws = Y

Therefore population density of species = Z/area of quadrant.

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