SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS OF THE INTERNATIONAL BACCALAUREATE DIPLOMA 2008-2010

HL Biology Lab Report

Macritchie Reservoir Comparison of Biodiversity between

Primary and Secondary Rainforest

Name Elliott ChapmanCandidate Number 000763-028School Overseas Family School

Center Number 000763Examination Session May 2010

Summary of Research

A. Importance

A diversity index provides important information about rarity and commonness of species in a community. The ability to quantify diversity in this way is an important tool for biologists trying to understand and compare community structures.1

B. Equation

Simpson's Index of Diversity = 1−D

Where:

D =∑n(n −1)N(N −1)

n = number of organisms of a particular species and;N = total number of organisms of all species.

C. Primary Forest

“Primary forest refers to untouched, pristine forest that exists in its original condition. This forest has been relatively unaffected by human activities. Primary rainforest is often characterized by a full ceiling canopy and usually several layers of understory. The ground floor is generally clear of heavy vegetation because the full canopy allows very little light, necessary for plant growth, to penetrate. Occasionally, when a canopy tree falls, a temporary "light gap" is opened in the canopy, allowing growth of floor and understory species. Primary forest is the most biologically diverse type of forest.”2

D. Secondary Forest

“Secondary forest is rainforest that has been disturbed in some way, naturally or unnaturally. Secondary forest can be created in a number of ways, from degraded forest recovering from selective logging, to areas cleared by slash-and-burn agriculture that have been reclaimed by forest. Generally, secondary forest is characterized (depending on its level of degradation) by a less developed canopy structure, smaller trees, and less diversity. Due to the lack of a full canopy, more light will reach the floor, supporting vigorous ground vegetation. "Jungle" is the term often applied to secondary forest with dense ground growth, but it is also applied to some tropical moist forests where seasonal variations permit thick ground growth.”2

1 Beals, Gross, and Harrel. "DIVERSITY INDICES." The Institute for Environmental Modeling at The University of Tennessee, Knoxville. N.p., n.d. Web. 16 Jan. 2010. <http://www.tiem.utk.edu/~mbeals/simpsonDI.html>.

2 "Types of Forest." Rainforests. N.p., n.d. Web. 13 Feb. 2010. <http://rainforests.mongabay.com

Introduction

A. Research Question

Is there any significant difference in biodiversity, measured using Simpson’s Diversity Index, between primary and secondary rainforest locations?

B. Aim

To determine and compare the biodiversity of primary and secondary forest areas in Macritchie Reservoir using the Simpsonʼs Index of Diversity.

C. Hypothesis

If a sample is taken from a Primary Forest, then it will have greater biodiversity, and thus a more favorable Index, than Secondary Forest. This is because Primary forest has a well developed canopy layer and multiple layers of understory, and larger range of flora has developed that can support animals. Such forest takes at least 100 years to grow, whereas Secondary Forest may only take 40 years and does not have a well developed canopy layer. There are however more plants on the forest floor as the light can penetrate to this level and support flora and fauna.

D. Variables

DependentDependent

Variable Description

Location The samples will be taken at a range of locations to get a fair reading of diversity in primary and secondary areas.

IndependentIndependent

Variable Description

Simpsonʼs Index of Diversity The outcome will be a calculated value which can represent numerically the diversity of a certain area.

1

ControlledControlled

Variable Description

Weather Rain could have washed away loose organisms; Heat may discourage certain organisms from coming out; Wind might have blown smaller organisms out of the sample area.

All experiments will be conducted one the same day and in a relatively short period of time negating any potential differences which would be observed over different times.

Foot Traffic People moving over this area would likely disturb the natural diversity by killing some flora and fauna.

Samples outside the most traversed areas will limit the disturbance and will be assured by the Ecofieldtrips staff.

Quadrat The area encompassed by the grid undoubtedly impacts the quantity of organisms collected and a reasonably sized quadrat will provide a fair sample of an area. Also the quadrat will need to remain constant to prevent discrepencies

The quadrats provided are specifically for this purpose and the same will be used throughout the experiment.

2

Process

A. Materials

Item Quantity Inaccuracy

Quadrat 1 N/A

Recording Sheet N/A N/A

Random number table 1 N/A

B. Method

The practical aspect of the experiment is carried out according to the intended method provided in the Ecofieldtrips Macritchie Reservoir booklet1:

• A grid will be set up to create a sampling area.• A quadrat will be used for sampling.• Use the random number table on page 12 to determine the coordinates for your

quadrat within the grid.• Position the quadrat with the bottom left hand corner on the point of your coordinates

- keep this constant.• Identify all species within the quadrat and the number of each species.

However the situation resulted instead that we did not need to use the random number table because the guides set up a quadrat for us right away. This reduced the supposed “randomness” nature of the sample, however as the overall forest areas were limited, we needed the guides to choose suitable areas to sample. Also limitations prevented us from venturing far off the path. The fact that we used 3 different sampling areas in each the primary and secondary forest makes this experiment more fair. Thus the revised method was as follows:

• A 5m2 quadrat will be used for sampling.• The Ecofieldtrips guides set up areas for us to visually sample from the path.• Identify all species within the quadrat and the number of each species.• Perform once at each of the 3 sampling sites in the primary and secondary forest

areas.

3

1 Ecofieldtrips Pte Ltd; 7G Jalan Kechubong, Singapore 799424; Tel: (+65) 65562034; Email: bridget@ecofieldtrips.com www.ecofieldtrips.com.sg

Data

A. Data Collection

Data in the field can be collected using this table. Each box represents a different species.

Site ⓟ / ⓢ - ① ② ③

( ) ( ) ( )

( ) ( ) ( )

Number Of Species

Aggregate Population (N)

B. Quantitate Results2

i. Table 1.1 - Summarized Data

Species

Populations (individuals) at Sample SitesPopulations (individuals) at Sample SitesPopulations (individuals) at Sample SitesPopulations (individuals) at Sample SitesPopulations (individuals) at Sample SitesPopulations (individuals) at Sample Sites

PrimaryPrimaryPrimary SecondarySecondarySecondary

1 2 3 1 2 3

1

2

3

4

5

6

7

Number (N)

Σn(n-1)

Diversity Index

2 5 6 4 15 9

1 4 4 2 3 6

10 1 1 1 1 2

2 1 7 1 4 1

1 2 2 2

10 3

1

15 22 20 19 23 24

94 122 86 16 228 112

0.552 0.736 0.774 0.953 0.549 0.797

42 Original data is included in the appendix

The table above displays the collected data. The three appended rows include the total aggregate population (N), which is a sum of the populations of each individual species in the area. “Σn(n-1)” is part of the calculation for the Simpsonʼs diversity index; it is the sum of the each species population individually multiplied by the population minus one. The final row is the diversity index which is calculated using the Simpsonʼs diversity index equation:

Simpsons Diversity Index = 1− ∑n(n −1)N(N −1)

ii. Figure 1.2 - Graph of Each Diversity Index

Primary Secondary

0

0.25

0.5

0.75

1

1 2 3 1 2 3

Simpsonʼs Index of Diversity for Primary and Secondary Sites

Sim

psonʼs

Inde

x of

Dive

rsity

The diagram above represents the various diversities amongst the 6 sites studied. It shows that the diversity between the three sites is within 0.5 and 1 which means that all the sites are closer to “no biodiversity” than they are to “infinite biodiversity.”

iii. Table 1.3 - Average Diversity Index of Primary and Secondary Forest

Diversity Index

Primary

Secondary

0.677

0.766

5

The table above indicates the average diversity for the primary and secondary sites. It is calculated using the results in Table 1.1 and shows that the Primary forest is more bio-diverse than secondary forest.

iv. Figure 1.4 - Graph of Average Diversity Index

C. Qualitative Results

Area Description

Primary The primary site was admittedly not true primary forest and the guides called it “mature secondary forest” which was evident as the canopy was not fully developed and there was some growth on the forest floor. This part of the forest was particularly protected; the paths were raised above the ground. Very little human disturbance.

The impact of this is that the results will likely show more similar results to secondary forest. However the more undisturbed and more protected nature of this forest mean that the plants have a greater chance to grow.

Secondary The secondary site was had more foot traffic through it and seemed more sparse. Some trash was noted. The trees were evidently younger and there was a relatively large amount of growth on the forest floor compared to the primary forest.

The more accessible nature of this part of the forest may mean that it can suffer from human disturbance.

0

0.25

0.5

0.75

1

Primary Secondary

Average Simpsonʼs Index of Diversity between Primary and Secondary Sites

Sim

psonʼs

Inde

x of

Dive

rsity

6

D. Uncertainties

The apparatus which we used did not include measurements for inaccuracy, however the quadrat provides some uncertainly that itʼs shape may not be a perfect square and therefore the area can differ from site to site.

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Outcome

A. Conclusion

a

B. Evaluation

a

8

Bibliography

Beals, Gross, and Harrel. "DIVERSITY INDICES." The Institute for Environmental Modeling at The University of Tennessee, Knoxville. N.p., n.d. Web. 16 Jan. 2010. <http://www.tiem.utk.edu/~mbeals/simpsonDI.html>.

Ecofieldtrips Pte Ltd; 7G Jalan Kechubong, Singapore 799424; Tel: (+65) 65562034; Email: bridget@ecofieldtrips.com www.ecofieldtrips.com.sg

APPENDIX

Site ⓟ / ⓢ - ① ② ③

( ) ( ) ( )

( ) ( ) ( )

( ) ( ) ( )

( ) ( ) ( )

Number Of Species

Aggregate Population (N)

Site ⓟ / ⓢ - ① ② ③

( ) ( ) ( )

( ) ( ) ( )

( ) ( ) ( )

( ) ( ) ( )

Number Of Species

Aggregate Population (N)

Site ⓟ / ⓢ - ① ② ③

( ) ( ) ( )

( ) ( ) ( )

( ) ( ) ( )

( ) ( ) ( )

Number Of Species

Aggregate Population (N)