Using quadrat sampling data from the given table estimate Population density and diversity index

 

2. Q: Using quadrat sampling data from the given table estimate:

1. Population density of each species
2. Shannon-Weiner diversity index (H')

Species	Quadrat 1	Quadrat 2	Quadrat 3	Quadrat 4	Quadrat 5	Total (Σni)
Species A	5	4	3	2	6	20
Species B	2	3	1	1	3	10
Species C	0	1	2	0	1	4
Total	7	8	6	3	10	34

 

SOLUTION:

Objective: To estimate species-wise population density and calculate biodiversity using the Shannon-Weiner diversity index formula from quadrat data.

1. Estimation of Population Density

Population Density = Total number of individuals of a species / Total number of quadrats

 

Density of Species A = 20 / 5 = 4.0

Density of Species B = 10 / 5 = 2.0

Density of Species C = 4 / 5 = 0.8 2

2. Shannon-Weiner Diversity Index (H')

Formula:

(H') Formula: H' = -SUM (p_i * ln p_i), where p_i = n_i / N

 

N = 34 (total individuals)

Step-by-Step Calculation:

Species	ni	pi = ni/N	ln(pi)	pi × ln(pi)
Species A	20	20/34 ≈ 0.588	≈ -0.531	≈ -0.312
Species B	10	10/34 ≈ 0.294	≈ -1.225	≈ -0.360
Species C	4	4/34 ≈ 0.118	≈ -2.140	≈ -0.252

 

H′=−(−0.312−0.360−0.252)=0.924H' = -(-0.312 - 0.360 - 0.252) = 0.924

 

Conclusion: Species A is the most dominant with highest density. Shannon-Weiner index (H' = 0.924) suggests a moderately diverse community. Density tells how many individuals of a species occur per unit area. H' Index quantifies species richness and evenness — higher values mean more diversity.