General Instructions:
- Copy the given assignment of practical in fair practical file of biology in the way discussed during class.
- Make the use of black pen for heading and sub-headings and blue pen for writing other content.
- Work should be presentable.
- Make well labelled and proper diagram as provided in this assignment.
Experiment No. 4
Aim: To study plant population frequency by quadrat method.
Materials Required: Meter scale, thread, nails, notebook, and hammer.
Theory:
Population
Population is defined as a group of individuals of same species which inhibit in a particular space at a patrician time. The number of individuals in a population never remains constant. It may change due to factors like mortality rate, natality rate, migration.
Population Frequency
Frequency represents the number of times a plant species is present with in a given number of sample quadrats. It is measured by noting the presence of species in random sample areas which are distributed as rudely as possible throughout the area of study.
Frequency = Number of quadrat in which the species occuredTotal number of quadrat studiedX 100
Quadrat Method:
A quadrat is a square that encloses an area within habitat. For herbaceous plant, a meter square 1mX1m quadrat is normally used.
Procedure:
- Select a field to study the population density of plants.
- Measure 1mX1m area with the help of meter scale in the field to make a quadrat.
- Fix four nails at the corner of the quadrat and tie end of nails suing a thread.
- Similarly make nine more quadrats randomly in field of study.
- Count and write the number of plants of a particular species in a quadrat
- Repeat same step with other quadrats also and record data in observation table
Observation table:
| S.No | Name of Species | Q1 | Q2 | Q3 | Q4 | Q5 | Q6 | Q7 | Q8 | Q9 | Q10 | Total Quadrats | Frequency |
| 1 | Cupressus torulosa | + | – | + | – | + | – | + | – | + | – | 5 | 50 % |
| 2 | Biota orientalis | – | + | – | + | – | + | _ | + | – | – | 4 | 40% |
| 3 | Quercus leucotrichophora | + | + | + | + | + | + | + | + | + | + | 10 | 100% |
| 4 | Platanus orientalis | + | – | + | + | – | – | + | + | – | + | 6 | 60% |
| 5 | Pinus roxburghii | + | + | + | + | – | – | + | + | + | + | 8 | 80% |
Calculations:
- Frequency for Cupressus torulosa:
Frequency = Number of quadrat in which the species occuredTotal number of quadrat studied X 100
Frequency = 510X 100 = 50%
- Frequency for Biota orientalis:
Frequency = Number of quadrat in which the species occuredTotal number of quadrat studied X 100
Frequency = 410X 100 = 40%
- Frequency for Quercus leucotrichophora:
Frequency = Number of quadrat in which the species occuredTotal number of quadrat studied X 100
Frequency = 1010X 100 = 100%
- Frequency for Platanus orientalis:
Frequency = Number of quadrat in which the species occuredTotal number of quadrat studied X 100
Frequency = 610X 100 = 60%
- Frequency for Pinus roxburghii:
Frequency = Number of quadrat in which the species occuredTotal number of quadrat studiedX 100
Frequency = 810X 100 = 80%
Resullt: Plant having highest frequency in area studied is Quercus leucotrichophora with 100 % frequency and plant having least frequency is Biota orientalis in studied area with frequency of 40%
Sources or error and precautions:
- Measure the quadrat accurate.
- Makr the quadrat close to each other in same field.