Study the Plant Population Frequency by Quadrat Method


The population of plant species in any geographical region can be determined by understanding the plant population frequency. Frequency is the degree of uniformity for plant species' individual occurrences. It is a bit hard to determine the plant population in large areas. The quadrat method is used to know the frequency of plant population.

What is the Quadrat Method?

Quadrat means a sample plot sized specifically to study a community or population. Quadrats have heavy usage in botanical purposes like plant density, plant biomass, and plant frequency determination. Quadrats' shapes and sizes control the frequency. Metre-square quadrats are generally used for herbaceous vegetation. The quadrat method is a popular technique to determine frequency variations in plant populations.

Figure 1: Quadrat Method

Plant Population Frequency in Quadrat Method

Plant population varies in different geographical locations and in different ecosystems. The frequency is the percentage ratio of plant species count in quadrats and number of sample quadrats. In the experiment results, the frequency value denotes how many times the plant species is present for a given count of sample quadrats.

Experiment Objectives

The objective of this experiment is to study the frequency of plant population with the help of the quadrat method.

Required Materials

Three materials are mandatory for this experiment. The materials required for this observation are

  • Nails

  • Hammer

  • Thread

Required Procedure

In biology, the frequency of plant population is studied with the help of the quadrat method. There are two types of procedures applicable to this method. The experiment is done both online and offline. The offline procedure is called real lab procedure and the online procedure is called simulator procedure. Both of them are discussed below.

Real Lab Procedure

  • In this process, the nails should be firmly hammered in the soil so that no damage could occur to vegetation.

  • Two pairs of nails need to be fixed to make a square shape.

  • The square-shaped quadrats’ dimension is 1 m x 1 m and to do this a thread needs to be used to tie each nail end.

  • In the same process 9 more quadrats needs to be prepared.

  • Then the plant species needs to be selected for the population frequency study.

  • Species A’s presence in this experiment needs to be observed in the first quadrat and it needs to be marked in the observation table.

  • In the same way, the other nine quadrats need to be checked carefully whether species A is present there or not. The output data needs to be entered in respective fields.

  • Then all the quadrats again need to be observed for the presence of species B and the results should be noted on the observation table in the same way.

  • This process should be repeated for species C and also the responses need to be marked on the table.

  • The following formula needs to be applied to determine plant population frequency Percentage Frequency=(Number of sampling units in which the species occurs)/(Total number of sampling units employed for the study)*100.

Simulator Procedure

Online labs are used to virtually perform this quadrat method. The steps required for the simulator procedure are mentioned below.

  • Each quadrat has its corresponding pop-up. The view can be enlarged by clicking on them.

  • The preferred study environment can be chosen from the select the environment dropdown menu.

  • Then the observations of plant species’ presence need to be noted down.

  • In the worksheet, the results need to be marked either with Y or N for the presence or absence of particular plants respectively.

  • Revert to the normal view by clicking the back button.

  • The population frequency for each plant species is determined by the entered values.

  • The reset option helps to perform this experiment again.


The following results can be observed from the above experiment. The plant species A, B and C are taken in the experiment and their presence in quadrats is taken as a sample here. Species A is observed in five random quadrats out of ten quadrats, therefore the quadrat count will be written as 5 and the frequency percentage will be 5/10*100=50. Similarly, for species B and C, if the number of quadrat count is 1 and 4, the frequency will be 10% AND 40% respectively.

Experiment Outcomes

The experiment gives a clear understanding of the term quadrat method. Students can get a clear knowledge of plant population frequency calculation. Better experiments can be done in real labs with simulation and animation.


The plant population is an important factor in ecosystems. Plant population frequency knowledge is necessary to know the status of the environment. The quadrat method is known to be the easiest method to know the frequency. The experiment is done through several steps using some materials. The above experiment shows the highest frequency in species A and the lowest frequency in species B. This way, the frequency differences of various plant populations can be determined.


Q1. What is meant by plant population frequency?

Ans. Frequency is the count of times a specified aspect can occur per unit time. The plant population frequency means the presence of particular plant species found out of the total number of plants taken for sampling.

Q2. How plant population frequency is calculated?

Ans. Plant population frequency is calculated by using the following formula.

Percentage Frequency = (Number of Sampling Units in which species occur) / (Total Number of Sampling Units Employed for the Study) * 100.

Q3. How frequency variation occurs in plants?

Ans. The frequency means the count of differences of plant species in a particular region at a certain time in comparison to the total number of plants in that region. Various controlling factors cause variation in frequency. They are soil conditions, soil quality, vegetation propagation, diseases, grazing, biotic activities, topography, area habitat, atmospheric conditions, and environmental conditions.

Updated on: 24-Apr-2023

1K+ Views

Kickstart Your Career

Get certified by completing the course

Get Started