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. 5
Aim: To study plant population density 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 Density
It represents the number of individual of the species in ay unit area at a specific time. The unit area may be small or large, depending on the size and nature of the plant community understudy.
Population density is calculated by counting all individuals present at a given space divided by the number of units of area of apace.
Density = Total number of individuals of a speciesTotal 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 Individuals | Total Quadrats | Density |
| Cupressus torulosa | 2 | – | 2 | – | 3 | – | 2 | – | 2 | – | 11 | 5 | 1.1 | |
| Biota orientalis | – | 1 | – | 2 | – | 2 | – | 2 | – | – | 7 | 4 | 0.7 | |
| Quercus leucotrichophora | 2 | 2 | 2 | 2 | 2 | 2 | 2 | 2 | 1 | 1 | 18 | 10 | 1.8 | |
| Platanus orientalis | 1 | – | 1 | 1 | – | – | 1 | 1 | – | 1 | 6 | 6 | 0.6 | |
| Pinus roxburghii | 1 | 1 | 2 | 2 | – | – | 1 | 1 | 1 | 1 | 10 | 8 | 1.0 |
Calculations:
- Density for Cupressus torulosa:
Density = Total number of individuals of a speciesTotal number of quadrat studied
Density = 1110=1.1
- Density for Biota orientalis:
Density = Total number of individuals of a speciesTotal number of quadrat studied
Density = 710= 0.7
- Density for Quercus leucotrichophora:
Density = Total number of individuals of a speciesTotal number of quadrat studied
Density = 1810= 1.8
- Density for Platanus orientalis:
Density = Total number of individuals of a speciesTotal number of quadrat studied
Density = 610= 0.6
- Density for Pinus roxburghii:
Density = Total number of individuals of a speciesTotal number of quadrat studied
Density = 1010= 1.0
Resullt: Plant having highest density in area studied is Cupressus torulosa and plant having least density is Platanus orientalis in studied area.
Sources or error and precautions:
- Measure the quadrat accurate.
- Mark the quadrat close to each other in same field.