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Home Biomedical Engineering Biology Class 12 Study the plant population frequency by quadrat method
Biology Class 12 Lab Experiments

Study the plant population frequency by quadrat method



Aim: To study plant frequency by quadrat method

Material/Apparatus Required:

  • Fields
  • Nails
  • Meter scale
  • Paper
  • Thread
  • Hammer

Principle:

Frequency: Determining plant population frequency using quadrat method has become popular primarily because it is relatively simple and objective. Frequency represents the number of times a plant species is present within a given number of sample quadrants. It is measured by noting the presence of a species in random sample arears which are distributed as widely as possible throughout the area of study. Once analyzed, the sample data enables us to calculate population frequency of the entire population by following method:

% Frequency = Number of sampling units in which the species occurs ×100 / Total number of sampling units employed for the study

Quadrat method: Calculate the plant population frequency using the quadrat is a simple plot of a specific size using for the study of population or a community. It is used in many different scientific disciplines like vegetation assessment, including plant density, plant frequency and plant biomass. Frequency is highly influenced by the size and shape of the quadrats used. The area that is chosen for the study must not be so big that it cannot be sampled adequately, or so small that the habitat is difficult for sampling. For herbaceous plants, a meter square (1 m × 1 m) quadrant is normally used.

Procedure:

  1. Select a field to study the population frequency of the plants.
  2. Measure 1 m × 1 m area with the help of meter scale in the field to make a quadrat.
  3. Fix four nails at the corner of the quadrant and tie each end of the nails using thread.
  4. Similarly, make nine more quadrats randomly in the fields.
  5. Select the plant species for the study of population frequency.
  6. Observe the presence of species ‘A' in the first quadrat and mark it in the table
  7. Similarly, check for the presence of species ‘A' in other quadrats respectively and record the data in the table.
  8. Repeat the same procedures for species ‘B' and ‘C' and record the data in the table.
  9. Calculate the percentage frequency of occurrence using the formula given below:

% Frequency = Number of sampling units in which the species occurs ×100 / Total number of sampling units employed for the study

Observation Table:

observation table

population frequency of plants

Result:

Frequency percentage of the species =Total number of quadrats in which species occur / Total number of quadrats studied

Precautions:

  1. Measure the quadrant accurately.
  2. Mark the quadrant close to each other from one field only
  3. Do not damage the vegetation while laying the quadrants