How Humans Are Impacting Tropical Rainforests on TiomanSeonaid

Seonaid Ferguson Environmental Systems and Societies 20th October 2009

How humans are impacting Tropical Rainforests on Tioman Island, Malaysia

A comparison between Primary and Secondary rainforests to compare plant diversity and soils.

Data Collection and Processing:

Primary Rainforest

Human impact assessment: 1; minimal human damage/90% of habitat intact

Figure 1; Primary Forest

Qualitative notes: There is a large amount of leaf litter on the forest floor. There are some red ribbons on some of the larger trees marking the way of the path, and impacted the rainforest. The trees are quite large and very tall and there is a large canopy. There are a few well developed strangler figs. The leaves on each of the trees are very large in order to get the most amount of sunlight. The terrain is much different as there are more hills, and there is more fauna here, with a lot more butterflies.

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Data to be used for the Simpsons Diversity Index:

Quadrat 1 Quadrat 2 Quadrat 3 Quadrat 4Species 1 1 2 2 2Species 2 1 4 4 5Species 3 1 5 24 20Species 4 7 1 11 18Species 5 3 3 2 1Species 6 1 2 1 3Species 7 2 1 2 1Species 8 0 0 1 1Species 9 0 0 1 1Total: 16 18 48 52

Simpsons Diversity Index = N (N−1)

∑ n(n−1)

SDI of All quadrats in Primary Rainforest= (134)(133)

7 (6 )+3 (2 )+2 (1 )+5 (4 )+5 (4 )+3 (2 )+2 (1 )+2 (1 )+4 (3 )+24 (23 )+11 (10 )+2 (1 )+2 (1 )+2 (1 )+5 (4 )+20 (19 )+18 (17 )+3(2)

=17822

42+6+2+20+6+2+2+12+552+110+2+2+2+20+380+306+6

=198221472

=13.46

Calculating Tree height:

Using the formula, we can calculate the height of the trees in the primary rain forest:

Tree height= [tan (a)*b] + [tan(c)*b]

Tree 1 Tree 2 Tree 3 Tree 4 Tree 5 Tree 6Ao 69 65 75 89 80 86Co -2 -13 4 30 27 15B/m 10 10 10 3.27 3.54 3.66Tree height/m

26.4 23.75 38 189.23 21.88 53.32

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Diameter at breast height:

DBH= Circumference

π

Circumference/m Diameter at breast height/m6.45 2.052.45 0.771.89 0.691.23 0.391.80 0.571.85 0.58

Comparison of Seedlings and Saplings.

Number of seedlings Number of saplings78 7

Light Readings taken inside in the quadrats:

Average light reading= the∑ of all the light readings

numberof light readings taken

Light readings/luxLight reading 1 252.9Light reading 2 140.4Light reading 3 487Light reading 4 131Light reading 5 97Light reading 6 163Light reading 7 49Light reading 8 147Average light reading 183.41

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Secondary Rainforest:

Human impact assessment: 4; 70% human impact/30% of habitat intact.

Figure 2; secondary forest quadrat

Qualitative notes:

There is a thin canopy layer in the rainforest; the trees used there are mostly small and thin. There are pipes running through the forest, and there was water running through these pipes which provided water to the plants. Light levels are much larger here, and there is light on the floor. There are a lot of ginger plants in the secondary rainforest which is being grown by the local people. There are a lot of butterflies and ants in this area.

Simpsons Diversity Index with 5m 2 quadrats:

Quadrat 1 Quadrat 2 Quadrat 3 Quadrat 4Species 1 12 190 103 148Species 2 3 3 1 1Species 3 2 8 4 3Species 4 3 1 3 2Species 5 99 2 22 16Species 6 2 1 2 2Species 7 0 1 0 0Species 8 0 1 0 0Species 9 0 1 0 0

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Total: 121 208 135 172

Simpson’s diversity index=N (N−1)

∑ n(n−1)

The Simpson Diversity Index of secondary rainforest=

636(635)12 (11 )+3 (2 )+2 (1 )+3 (2 )+99 (98 )+2 (1 )+190 (189 )+3 (2 )+8 (7 )+2 (1 )+103 (102 )+4 (3 )+3 (2 )+22 (21 )+2 (1 )+148 (147 )+3 (2 )+2 (1 )+16 (15 )+2(1)

=40386078818

=5.12

Calculating Tree height:

Using the formula, we can calculate the height of the trees in the primary rain forest:

Tree height= [tan (a)*b] + [tan(c)*b]

Tree 1 Tree 2 Tree 3 Tree 4 Tree 5 Tree 6A/o 47 65 44 75 70 63C/o -13 -4 -11 20 15 3B/m 10 10 10 5.28 7.1 5.44Tree height/m

13.03m 22.14m 11.6m 21.63 21.4 10.96

Diameter at breast height:

DBH= Circumference

π

Circumference/m Diameter at breast height/m0.62 0.191.1625 0.370.58 0.183.45 1.091.17 0.371.00 0.32

Comparison of Seedlings and Saplings.

Number of seedlings Number of saplings9 12

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Light Readings taken from inside the quadrats:

Average light reading= the∑ of all the light readings

numberof light readings taken

Light readings/luxLight reading 1 534Light reading 2 1135Light reading 3 176Light reading 4 345Light reading 5 1106Light reading 6 272Light reading 7 575Light reading 8 614Average light reading 594.625

Primary Rainfroet Secondary Rainforest02468

101214

13.46

5.12

Simpson's Diversity Index comparison of Primary and Secondary Rainforest

Simpsons Diversity Index

Rainforest Type

Sim

pson

's Di

vers

ity In

dex

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1 2 3 4 5 60

20

40

60

80

100

120

140

160

180

200

26.4 23.7538

189.23

21.88

53.32

13.03 22.1411.6

21.63 21.4 10.96

Comparision of Tree heights of Primary and Secondary Rainforest

PrimarySecondary

Tree number

Heig

ht o

f tre

es/c

m

1 2 3 4 5 60

50

100

150

200

250

1937

18

109

37 32

205

7769

3957 58

Comparision of DBH in primary and secondary rainforest

DBH of secondary rainforestDBH of primary rainforest

Tree number

DBH/

cm

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Primary Rainforest Secondary Rainforest0

10

20

30

40

50

60

70

80

7

12

78

9

Comparision of seedlings and saplings in Primary and Secondary Rainforest

Saplingsseedlings

Forest Type

Num

ber o

f See

dlin

gs a

nd S

aplin

gs

Primary Rainforest Secondary Rainforest0

100

200

300

400

500

600

183.41

594.625

Comparision of average light readings in the primary and secondary rainforest

Average light reading/lux

Forest type

Aver

age

light

read

ing/

lux

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Discussion, Conclusion and Evaluation

Firstly, I think we should define what exactly primary and secondary rainforest is. Secondary rainforest is the rainforest which has experienced disturbance by logging, clearing for plantations of the collapse of primary rainforest trees. In the case of Tioman Island, it was cleared a lot for plantations. The primary rainforest is the rainforest has reached its climax community and had not experienced disturbances. In most cases, the primary rainforest has most diversity, larger trees, less sunlight and more mature trees than that of the secondary rainforest which has a smaller biodiversity, smaller trees, more sunlight due to a smaller canopy layer and younger, less mature trees.

My results show that there are large differences between the types of forests in all tests conducted. By looking at the graph showing the Simpson’s diversity index (SDI), we can see that the SDI of the primary rainforest is much larger at 11.34 compared to the secondary rainforest whereas the SDI of the secondary rainforest was 5.12. The larger the SDI, the more diversity of the area, so from my data, we can see that primary rainforest is much more diverse. Henceforth, we can deduce that reforestation has a large effect on the diversity of the rainforest as the secondary forest which was cleared in Tioman for rubber plantations, had a smaller diversity than that of the primary rainforest remaining.

We then looked at the tree heights of the trees, and the tree heights shown in the graph show the differences in height. From the graph, we can see that generally, the trees in primary rainforest are much larger than in the secondary forest, as these trees in the primary rainforest are part of the climax community and henceforth are much larger. There is an anomaly on tree five in which the tree heights between secondary and primary are of very similar sizes, which could be because the light doesn’t reach the primary forest and hence the speed that trees grow at is slower than the secondary rainforest.

When we compared the diameter at breast height (DBH), we can see that generally the diameter at breast height was much larger in the primary rainforest than in the secondary rainforest.

When comparing seedlings and saplings, we should obviously define what exactly each one is. A seedling is a young tree which is less than 1m high, whereas a sapling is a strong young tree which is taller than 1m, and smaller than 6m. The primary rainforest has fewer saplings than in the secondary rainforest. The secondary rainforest has more saplings as there is light coming through so there are more young trees to grow quicker. In the primary rainforest, there are more seedlings than in the secondary rainforest. There are a lot of seeds being dropped in the forest floor but due to the lack of light on the forest floor, they hardly ever grow that tall.

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By comparing the average light sample between the two different forest types, we can see that the light in the secondary rainforest is much higher at 594.625 lux on average than in the primary forest where its only 183.41 lux on average. This is because the canopy layer on the secondary rainforest is much smaller than in the primary rainforest and the light can still manage to get through to the forest floor. But in the primary rainforest has a much smaller average light reading because the canopy layer in the primary rainforest is very large and not much light can get to the forest floor where the light readings were taken.

I think that some of the weakness’s in the group were that there weren’t enough repeats, as ideally there should be at least 5-10 repeats for each experiment, especially for the Simpsons diversity index and for the comparison of tree heights and DBH. By repeating the experiments, there would be fewer inaccuracies and hence why you could calculate more averages for each of the experiments for example the Simpsons diversity index.

Additionally half of the quadrats were conducted by one group, and the other two quadrats were conducted by the other. This could be a large inaccuracy because there could be different methods conducted by each group. Additionally for the Simpsons Diversity Index, the identification of each species were different as not the same species were in the same quadrats, even though it probably didn’t affect the results as the names weren’t required, only species numbers, it would’ve been more accurate to have the same names on the tables. If we had one group doing the whole identification process with keys labelling each tree, then each species would be identified and named.

By having more replications we could get more accurate results as ideally, they should be repeated 5-10 times but we only have 4 repeats. By repeating more times, there would be a better average for all the experiments.

The quadrats used could’ve been more precise as they were made out of plastic string and sticks, if there was a more accurate quadrat, it would’ve been better for the accuracy of the results

Additionally, we could do other experiments such as the Maturity Index which would tell us how mature the total primary rainforest is and then we would be able to compare it to the secondary rainforest, and I would expect the primary rainforest would have a higher maturity index. Also, we could do the leaf litter survey which we would measure the amount of leaf litter in each forest. By performing more tests, we could get a more accurate comparison between the two types of rainforests.

Overall, we can see that the human impact on Tioman Island is very large. Where humans have interfered with the ecosystem, the diversity is much lower than that of no interference. The trees are much smaller than what they are in the undisturbed area, and there is a lot more light in the secondary forest than in the primary rainforest.

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