Page 11 - Biology - XII

5. Then, carefully examine/study the type or types of plants in this quadrat (10 cm × 10 cm).
6. Note down the number of plant species.

7. Repeat the process by—
Increase in the quadrat area to 20 cm × 20 cm followed by next quadrat area to 30 cm × 30 cm and till
you reach quadrat area 1 m × 1 m.
8. Record your observation in your practical record fi le.

Observations
Plant population in minimum quadrats

S. No. Quadrat size Total number of plant species present
1. 10 × 10 cm 2

2. 20 × 20 cm 2
3. 30 × 30 cm 2

4. 100 × 100 cm 2

Calculationof populationdensity = Total numberofplantsoffa species

Total numberof quadrats
Conclusion
There are ___________ number(s) of plant species in Quadrat no. ___________ .

Precautions
1. Select a good/wildly growing/cultivated area.
2. Carefully count the plants. Do not make a mistake to recount the plants. (It will give wrong results.)
3. Select one species of plant population for counting at one time.
4. Plants coming under the string can be avoided.

5. Note the data immediately in the observation table.

EXPERIMENT - 2

Objective
To study the plant population frequency of diff erent plants species by quadrat method.

Principle/Theory
Frequency is defi ned as the number of times it occurs. In case
of plant species, the frequency is the degree of uniformity
of the occurrence of the individual species within a plant
community being studied. It is measured by noting but the
presence of the plant species in quadrats which are widely
distributed. The frequency of each species in the community
is expressed in percentage and it is calculated as

Fig. 2.1: Grass fi eld with a variety of plants

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