8.3 Population Ecology

8.3 Population Ecology

What is meant by population ecology? A

branch of ecology that studies the structure and dynamics of population.  Population density – number of organism per unit area of habitat  Affected by abiotic and biotic factors, birth rate, death rate, immigration and emigration.

 Direct

counting – method to estimate the size and density of population (impractical due to the size of ecosystem, the number of plants involved and the movement of the animal).  Sampling technique – more practical way, enable us to estimate the total population size of the organism.

The quadrat sampling technique  Used

in estimating the size of plant population and immobile animal.  A quadrat – metal, wooden frame or PVC pipe frame which form a square of a known area (1 m2).  Placed randomly in an ecosystem where sampling is carried out.

The quadrat sampling technique

The quadrat sampling technique Used to determine: (b) Frequency – number of times a particular species is found present when a quadrat is thrown a certain number of time 

The quadrat sampling technique (b) Density – the mean number of individuals of species per unit area

(c) Percentage coverage – an indication of how much the area of quadrat is occupied by a species

The capture, mark, release and recapture technique      

Used to estimate mobile animals (small mammals, butterflies, birds and insects) Procedure: Animal sample is captured Marked Released Second sample captured & number of marked animal recorded.

The capture, mark, release and recapture technique  Population

size of the animal in the area can be estimated using the formula below:

The abiotic factors which influence the distribution of an organism  What

are abiotic factors?  How the abiotic factors influence the distribution of an organism?

Exercise  Do

Focus Practice 8.3 on page 188 in the textbook.