Schoolyard Ecology
Background: Measure of diversity has been of historical significance and their importance still remains today given the obvious
declines in habitat quality in almost every ecological system. The Shannon-Wiener diversity index, historically, has been used to
measure the effects of habitat quality. Recently, newer indices have incorporated habitat parameters and are termed, appropriately
enough, Habitat Suitability Indices (HSI). Though the results of the Shannon Wiener index needs to be used with caution, it provides a
good learning tool for comparing two distinct habitats.
The S-W index is a measure of the likelihood that the next individual will be the same species as the previous sample.
When pollution is present or a human disturbance has occurred in a community, biodiversity is typically lower than in an undisturbed
community. Maintaining biodiversity is important for a variety of reasons:
-
New medicines have been discovered by screening diverse ecosystems
Genetic diversity in crop plants and their wild relatives provides breeders with the “raw material” needed to select
for traits in response to new agricultural challenges
Diverse communities are generally less susceptible to perturbation than similar but less diverse communities
Species diversity is a combination of species richness and species evenness
-
Species richness is the total number of species present in the community
Species evenness is the relative distribution of individuals among the species present in a community
o Evenness contrasts with dominance and is maximized when all species have the same number of individuals
o Species equitability (how even are the numbers of individuals of each species). For instance, say we have a
sample of 100 fish containing only 2 species. We would say that the species are equitable if there were 50 of
each species. Conversely, if there were 99 of 1 species and only 1 of the other, there would be no equitability.
Given this second scenario, we would be pretty confident in our prediction that if we were to sample 1 more
individual that it would be the same as the 99 in that sample. Conversely, in the previous scenario, we would
have a 50/50 chance at predicting the next species sampled.
The Diversity Indices:
Species Richness (R)
The species richness is based solely on the number of species found in the given area and does not reflect the relative dominance of
species.
R=s
Where:
s = the number of species
Shannon-Wiener Index (H)
H= -sum (Pi ln(Pi))
or
𝑺
𝐇 = − ∑𝒊=𝟏 𝐏𝐢(𝐥𝐧(𝐏𝐢))
Pi = relative abundance = ni/N
ni = number of individuals of species “i ”
N= total number of individuals of all species
H (the uncertainty of predicting a the species) will range from 0 for a community with a single species to over 7 for a very diverse
community.
A rich ecosystem with a high species diversity has a large value for the S-W Index (H), while an ecosystem with little diversity has a low
(H) value
Species Evenness (E)
Evenness (E) in a measure of how similar the abundance of different species are. When there are similar proportions of all species
then evenness is one, but when the abundance are very dissimilar (some rare and common species) then the value increases
E = H/ (lnR)
Pre-Lab Questions:
1. A sample community of 256 individuals is comprised of 5 different species and the frequency of each species is recorded
below. Complete the table and determine the R, H and E value.
Fish Species
Table 1
Frequency
Pi
ln(Pi)
Species #1
84
0.3281 -1.1144
Species #2
4
0.0156 -4.1589
Species #3
91
0.3555
Species #4
34
Species #5
43
Sum=
1
Pi*ln(Pi)
-0.3656

H value
Calculate:
R=
H=
E=
2. Use all three indices to determine which of the following three communities of 100 individuals is the most diverse:
a. Community 1 contains 10 species. 91 individuals make up the first species and one individual in each of the
remaining species.
b. Community 2 also contains 10 species. There are 10 individuals in each species.
c. Community 3 only contains 5 species. There are 20 individuals in each species.
You must SHOW and EXPLAIN your work for credit:
Schoolyard Ecology
You and a partner will calculate the diversity of a fragmented ecosystem on campus and compare student to teacher parking lots, a car
dealership as well as other school parking lots across the nation. Your “ecosystem” will be the school parking lot and the “species” will
be the different car models (Mustang, Civic, Camry, etc). After determining the number of each species in each fragmented ecosystem,
the Shannon Diversity Index will be calculated and compared to other fragmented ecosystems.
Hypothesis:
Determine the species diversity for each comparison:
Of all ecosystems analyzed which will be most diverse? Why?
On campus- Student or Teacher? Why?
Total campus vs. Car dealership? Why?
Our campus vs. _____________________________________ why?
Procedure:
1. Once outside in the parking lot your teacher will assign you and your partner a specific ecosystem-make sure to record data for
only your assigned ecosystem.
2. Tally every species within your ecosystem- there is not an unlimited time for data collection so be efficient.
3. If you are having difficulty classifying a species, come to a decision as a team and/or take a picture for further analysis- no
individuals are to be skipped.
4. If any species are immigrating or emigrating (cars coming and going) during the sampling time they need to be recorded.
5. The table below is current car data for a Chevrolet dealership located in Arlington, Tx. Complete the table with the information
provided.
Sample Table- Chevrolet Car Dealership Arlington, Tx
i
ni
pi
ln pi
Species
1
(species “#1”)
2
3
4
5
6
7
8
9
10
11
12
Silverado
Equinox
Cruze
Malibu
Taho
Sonic
Spark
Camaro
Suburban
Traverse
Impala
Corvette
S=
73
individuals
12
15
24
19
10
3
12
7
12
45
5
N=
Total number of
species
Total
individuals
pi ln pi
ni/N=
1.00
-
H = sum (Pi ln(Pi))
H=
6. Create and attach a data table, like the Sample Table, for the teacher parking lot and student parking lot that provides enough
space to include all of your findings and calculations. Attach to the back of your lab.
7. Complete Table 2 below comparing your ecosystems with the other parking lots.
Table 2
Diversity
Measurements
Teacher Lot
Student Lot
Campus
(student +
teacher)
Car
Dealership
Other campus
located
in______________
Most abundant species:
Species richness (R)
Evenness (E)
S-W Index (H)
Relative Diversity
(rank the lots with the most
diverse being a 1)
Conclusions:
Individually summarize your analysis of the data clearly and concisely on a separate piece of paper or typed up. Write your answers in
COMPLETE SENTENCES.
1. The importance of biodiversity has been correlated to ecosystem resilience and stability. According to your results,
which parking lot demonstrates the higher degree of ecological stability?
2. If an ecosystem has an H value close to 0 what does that tell you about the diversity of that ecosystem?
3. Which ecosystem on our campus was most diverse? Based on your observations during the lab, explain why your
hypothesis was supported or disproved.
4. When comparing our total campus to the car dealership, which ecosystem was most diverse? Explain why your
hypothesis was supported or disproved.
5. When comparing our total campus to another campus, which ecosystem was most diverse? Explain why your
hypothesis was supported or disproved.
6. Each parking lot had an abundant species (recorded in Table 2). Provide a plausible explanation for each abundant
species as to why it was the so abundant in it’s particular ecosystem.
7. If you conducted this lab in a shopping mall parking lot, predict whether the Shannon Diversity Index would be
higher or lower compared to a school’s parking lot and compared to a car dealership. Justify your answer.
8. Were our “organisms” easy or difficult to study? Why or why not? How does this relate to real, living organisms in
the wild? What implications might this have on actual ecological field research?
9. Were there opportunities for errors in your methods of conclusions? If so, explain.