How do we measure biodiversity in a particular habitat?
Here are three exercises to enable the students to explore the concept of biodiversity
through species richness, creating a species-scape and species evenness. These materials
are based on those of Gilbert and Brown (2010) but modified to reflect a tropical
environment.
1. Species richness
Students can be asked what data they should collect to measure biodiversity in Habitat A
and Habitat B (see species richness.pptx). In each habitat the total number of species (the
species richness) is the same. You can then go on to discuss which habitat has the greatest
biodiversity by counting the number of individuals per species (see ‘Species evenness’
later).
2. Species-scape
This can be used to represent the size of the different taxonomic classes represented in the
habitat.
The students do not need to identify the individual species on the sheet below (Fig. 1), just to
recognise different species and which taxonomic group they belong to. As such it will
illustrate some of the basic principles of classification. Tally up the number of species in
each taxonomic group (Table 1 with results completed, Table 2 blank for students). You
could represent this data in various ways e.g. pie chart or histogram or even try a speciesscape where each taxon is drawn as a representative species. The size of the animal (in
this example) is proportional to the number of different species within the taxon (see species
scape.pptx, note that the size of the different animals in the scene is only representative).
For a good example of a species-scape have a look at the Natural History Museum’s
Biodiversity site (http://www.nhm.ac.uk/eb/speciesscape.shtml)
Table 1: Data collected for species-scape
Number of species
Taxon
Tally
Total
Amphibians
1
Birds
5
Fish
2
Insects
4
Mammals
3
Reptiles
1
Total
16
Figure 1. on following page.
Table 2. Data for species-scape
Number of species
Taxon
Tally
Amphibians
Birds
Fish
Insects
Mammals
Reptiles
Total
Total
3. Species evenness
We need to consider other factors than the number of species when looking at measures of
biodiversity, e.g. the number of individuals per species as in the first exercise. Even this may
be misleading as in some cases there may be little genetic variation between individuals e.g.
cheetahs or individuals may even be genetically identical if they are clones as occurs in
many plant species.
The next example shows two habitats with equal numbers of species (species richness) and
number of individuals per species (species evenness). However, Habitat A (See species
evenness.pptx) has greater biodiversity than B because it includes species from a greater
range of taxonomic groups.
Source:
Gilbert L and Brown L (2010) Teaching biodiversity: a successful approach. School Science
Review 91: 81-87
Pictures sourced from Wikipedia and are creative commons.
Additional pictures by LJ Atkinson