To determine population density and per- centage frequency of different plant species of a given area.

                           EXPERIMENT 02

OBJECT - To determine population density and per-

centage frequency of different plant species of a

given area.

REQUIREMENTS

Metre scale, string or cord, nails, paper, pencil etc.

 

PROCEDURE

(a) Determination of the size of Quadrat.

Prepare a L shaped structure in the field of

1 mx 1 m by using 3 nails and tying a string

with them. Now measure 10 cm on one side

of the arm of L and then the other. Prepare

10 x 10 sq. cm area using another piece of

string. Count the number of species occurring

in this area. Increase this area to 20 x 20 sq. cm

and similarly record additional species

occurring in this area. Repeat the same

procedure till 1 x 1 sq. m area covered. 

Using the above recorded data, prepare a graph. Number of species are plotted on Y axis and size of the quadrats on X axis. At one point of graph, curve starts flattening or shows only a gradual increase. This point denotes minimum area of the quadrant suitable for the study of an area under consideration.

Fig. 2.2. Species area curve to determine the size of the quadrat.

b) Determination of Population density and percentage frequency. Take a quadrat of suitable size,lay it randomly at number of places. Count the number of each plant species present in the quadrat. If the number of plants in the quadrat is large, the quadrat can be divided into smaller sub-units and the sum total of all the sub-units will give the number of individuals of a species in the quadrat. Record the data in the observation table.

Population Density =

Total No. of individuals in all the quadrats studied

Total No. of quadrats studied

Percentage Frequency =

Total No. of quadrats in which species occured × 100

Total No. of quadrats studied

PRECAUTIONS

1 The measurement of quadrats should be accurate.

2.The string or cord used should not be very thick.

3.One individual of a species should be counted only once in the quadrat. 

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