BIODIVERSITY IN LEAF LITTER
PURPOSE: The purpose of this lab is to measure the biodiversity of organisms found in a sample of
leaf litter and calculate Simpson’s Index of Diversity
BACKGROUND: Species diversity is a characteristic that is unique to a community level of biological
organization. The biodiversity in different communities has been severely affected by human
activities. A community is said to have high species diversity if it has many species present in
approximately equally abundant numbers. If it is composed of only a few species or if only a few
species are abundant, then the biodiversity is said to be low. If a community has 100 individuals
distributed among 10 species then the maximum possible diversity would occur if there were 10
individuals in each of the 10 species. The minimum possible diversity would occur if there were 91
individuals belonging to 1 species and only 1 individual in each of the other nine species.
The number of species in a community is very important. There seems to be evidence that the greater
the species diversity, the more stable the community. With severe disturbances such as pollution,
habitat fragmentation, soil erosion, etc., diversity may decline.
IN THIS LAB: We will use Simpson’s Index of Diversity. We will first determine the relative abundance
of each individual species. Abundance compares the number of organisms of a particular species with
the total number of organisms found in the sample. We will also measure the dominance.
Dominance is the probability that two randomly selected individuals would belong to different
species. A community with a high diversity will have a low dominance.
The following are examples of how to calculate abundance and how to use Simpson’s Index to
determine diversity.
Species (i)
1
2
3
S=3
Abundance (ni)
50
25
10
N = 85
MATERIALS:
1 Dissecting Microscope
1 Berlese Funnel (inverted plastic bottle)
Leaf Litter Sample
1 beaker
Relative Abundance (pi)
50/85 = .588
25/85 = .294
10/85 = .118
Alcohol/water mixture
1 x heat lamp
rubberband
cheesecloth or mesh
To collect small organisms, a Berlese Funnel is commonly used. A sample is collected and placed in a
funnel with a screen below the litter. A bright light is placed above the funnel and a container of
alcohol is placed below the funnel. Negative photoaxis (the tendancy to move away from light)
causes organisms/invertebrates to drop from the litter into the beaker.
DATA TABLE:
Description of type of biome studied: ___________________________ Location of sample site:____________________________
Species
1
Name
Number of organisms
2
3
4
5
6
7
8
9
10

If you are unable to identify a species, just call it x,y,z.
DISCUSSION:
1. Calculate the diversity index using the example given below. REPORT your value here_______________________ then share your
index value on the class data table.
2. How is the funnel able to separate the organisms from the leaf litter?
3. Which site had the highest biodiversity? ________________________
Which site had the lowest biodiversity? _________________________
4. Do the biodiversity values give you an idea of which sites were more stable?
5. Name two biotic and abiotic factors which might be responsible for differences in location index values.
Simpson’s Diversity Index Example
Species (i)
Abundance (ni)
Snail A
Snail B
Insect A
50
25
10
N = 85
Simpson’s Diversity Index USING YOUR DATA
CLASS DATA – Simpson’s Biodiversity Index – Leaf Litter Lab
LOCATION/ SITE NAME
BIODIVERSITY INDEX VALUE
TOTAL Number of organisms present
in sample