IB Environmental Systems & Societies
AP Environmental Science
Biodiversity Worksheet
Biodiversity: (1) the number of different species in a given area; (2) the range of genetic material present in a
species or population; (3) the number of different habitats per unit area in a given ecosystem or biome.
Measuring biodiversity can involve several different tasks: (1) selecting an area to sample; (2) identifying
different species; and (3) counting species and/or organisms:
Sampling Techniques
 Quadrats
o for stationary organisms
o analyzes a sample of the overall area
o must sample enough quadrats to obtain representative sample
 rule of thumb is ~ 10%
 may need fewer or more depending on distribution of species
o sample must be unbiased
 systematic sampling – every third quadrat, for example
 random sampling – number quadrats and draw numbers from a hat, or close your eyes
and toss a square, etc.
 Consistent Estimating
o useful for comparison purposes (one habitat vs. another)
o appropriate for mobile organisms
o for example, compare number of species or individuals identified per unit of time spent looking
o attempt to obtain representative samples; avoid bias
Diversity Index:
 Example: Simpson-Yale diversity index (D):
N = total number of individuals
n = number of individuals of each species
D = N(N-1)
Σn(n-1)
Example:
Two areas 5m x 5m of Australian coast:
Young Dune
S. longifolius 7
S. hirsutus
12
T. divaricator 4
C. maritima
1
24
Young Dune
D=
Old Dune
D=
Older dune
A. cyclops
P. capitatum
O. axillaries
C. brownii
A. populifolia
S. elegans
24 x 23
(7x6) + (12x11) + (4x3) + (1x0)
2
2
4
4
3
2
17
= 2.97
17 x 16
= 7.56
(2) + (2) + (4x3) + (4x3) + (2x3) + 2
Old dune is therefore more diverse, despite having fewer total plants. (That is because, in general,
biodiversity of an ecosystem increases with time.)
IB Environmental Systems & Societies
AP Environmental Science
Names: ___________________________________________________________________________________
Date: ___________________
Area 1
Area (m2):
Species Name (if known,
otherwise use a number)
Species Description
Area 2
Area (m2):
Species Name (if known,
otherwise use a number)
Which area has more species diversity? Why?
Species Description