Download biodiversity activity

BIODIVERSITY ACTIVITY
Background
Biodiversity has become a rather hot topic within the field of ecology and this interest
has more recently reached the general public. For example, school children are
commonly taught that the tropical rain forests are some of the most diverse habitats on
Earth and that this diversity is under attack through deforestation. But how is
biodiversity measured? One common measure of biodiversity is called the “species
richness”, which is defined as the total number of distinct species within an area and
represented by the variable S. Another common measure is called “species diversity”
and can be calculated using the Shannon-Weaver equation below.
H = -[(ni/N) ln (ni/N)]
where ni = the number of individuals of a given species in the sample area
N = the total number of individuals in the sample area
Materials
Meter Stick
Insect Net
Calculator
Procedure
Field Vegetation
1. In your assigned group, acquire a meter stick and walk quietly outdoors to the field
adjacent to off school property.
2. One group member chose a number between 1 and 100 and have one other group
member make one guess of the number. Determine the difference between the
chosen number and the number guessed. Starting at the street, walk that chosen
number of steps to the west along the mowed edge between the field and the school
property.
3. Have another group member chose a number between 1 and 100 this time, and have
the group member that chose the first number guess the number this time.
Determine the difference between the chosen number and the number guessed.
Starting at your point along the edge of the field, walk that chosen number north into
the field.
4. Place your meter stick on the ground perpendicular to the line of walking at the point
that you have located. Imagine a complete one-meter square area in front of the
meter stick.
5. First, make a brief and inaccurate but identifiable sketch of the species of plants in
your area (question 1). Then, determine the “species richness” of the meter square
area and record it with question 1.
6. Next, estimate the percentage of the area that each species composes. Realize that
one meter is composed of ten decimeters and that the meter square is composed of
one-hundred separate square decimeters. Thus, an accurate estimate could be
aided by determining how many of the hundred separate squares a particular
species is found in. Record your percentages in the data table in question 1. These
estimated percentages are equivalent to the relative abundance for that species in
decimal form. Rerecord the relative abundance in decimal form in the
7. Then, given the sample calculation that follows determine the plant biodiversity for
your sample and show your work and final answer in the appropriate places in the
table associated with question 2.
Species A = 20%, Species B = 80%
H = -[(ni/N) ln (ni/N)]
= -[(0.20) ln (0.20)] + [(0.80) ln (0.80)]
= -[(0.20)(-1.609437912)] + [(0.80) (0.223143551)]
= -[(-0.321887582)] + [(-0.178514841)]
= -[(-0.500402423)]
= 0.50
Insect Diversity
1. After collecting data for the plant biodiversity, use the insect net to collect a
representative sample of insects in the field, using the method demonstrated.
2. When finished collecting your sample of insects, carefully allow them to crawl up and
out of the net – they will reach the top and fly away. Identify each species observed
with a letter in the data table and make a tally for each specimen of each species.
3. Use the calculator to sum the number of individuals for each species to determine the
total number of individuals in the sample, N.
4. Then, use the calculator to calculate the relative abundance for each species, the
portion of species diversity for each species, and the total species diversity, ni/N.
5. Finally, calculate the species diversity insects, and answer the questions that remain.
BIODIVERSITY OF A FIELD QUESTIONS
Name: ____________________________
1. Species Data Table, Species Richness = S = ______
Species A
Species B
Species C
Species D
% = _____
% = _____
% = _____
% = _____
Species E
Species F
Species G
Species H
% = _____
% = _____
% = _____
% = _____
Species I
Species J
Species K
Species L
% = _____
% = _____
% = _____
% = _____
2. Plant and Insect Biodiversity Data and Calculation Table
PLANT DATA &
CALCULATIONS
Relative
Species Abundance
(ni/N)
A
MidCalculation
[(ni/N) ln (ni/N)]
INSECT DATA & CALCULATIONS
Tally # of
Individuals
(ni)
Relative
Abundance
(ni/N)
MidCalculation
[(ni/N) ln (ni/N)]
B
C
D
E
F
G
H
I
J
K
L
-
H=
N=
-
H=
3. Analyze the biodiversity of the plants and insects in the field based on the knowledge
that you have gained so far this semester.
4. Identify the three distinct levels of biodiversity and explain how each is important.
_____________________ -
_____________________ -
_____________________ -
5. Identify the four major threats to biodiversity and explain how each is a threat.
_____________________ -
_____________________ -
_____________________ -
_____________________ -
5. What is restoration ecology? And what are the two common methods used by such
ecologists in their restoration work?
6. What community or species interaction most likely exists between the plants
observed? Explain.
7. From your observations does it appear that some plants are more competitive?
Explain.
8. Assuming you understand the concept of an ecological niche, what two possible
scenarios could explain the lower population levels of some of the other plant
species?
9. Assuming that this field would look exactly the same a year from now (the biodiversity
is unchanging, etc…), why might those species that are less abundant be able to
maintain themselves amongst the others?
10. Are the most abundant species of plants in the field more likely “dominant species”
or “keystone species”? Explain.
11. What community or species interaction most likely exists between the plants and
the more abundant insects that you collected? Explain.
12. Base on your knowledge of the flow of energy in ecosystems, what community or
species interaction most likely exists between the more abundant and less abundant
insect species? Explain.
13. Identify and describe at least three of the other distinct community or species
interactions.