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DIVERSITY, CARBON STOCK AND SUCCESSIONAL PATTERN OF
UNDERSTORY HERBACEOUS PLANTS IN FALLOW SHIFTING CULTIVATION
AT SABAL AGROFORESTRY CENTRE, SARAWAK
NOORHANA BINTI MOHD SAPAWI
A thesis submitted
In fulfillment of the requirements for the degree of Master Science
(Botany)
Faculty of Resource Science and Technology
UNIVERSITI MALAYSIA SARAWAK
2013
DIVERSITY, CARBON STOCK AND SUCCESSIONAL PATTERN OF
UNDERSTORY HERBACEOUS PLANTS IN FALLOW SHIFTING
CULTIVATION AT SABAL AGROFORESTRY CENTRE, SARAWAK
Noorhana binti Mohd Sapawi
2013
(Botany)
Faculty of Resource Science and Technology
i
DECLARATION
I hereby declare that this thesis is based on my original work except for quotations and
citations which have been duly acknowledged. I also declare that this thesis has not
been previously or concurrently submitted for any other degree of qualification to any
other university or institution of higher learning.
……………………………………………..
(Noorhana binti Mohd Sapawi)
(Postgraduate Student No.: 09021449)
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ACKNOWLEDGEMENTS
I would like to express my appreciation to my supervisor, Professor Dr. Isa Ipor
for his guidance and support throughout this study. To my co-supervisors, Professor Dr.
Cheksum Tawan, Associate Professor Dr. Petrus Bulan and En. Qammil Muzzammil
Abdullah, thank you for the advices and encouraging comments.
I would like to extend my thanks to the FSTS’s laboratory assistant especially
En. Hidir Marzuki and En. Sekudan Tedong for teaching and helping me with the plant
identification. Also, many thanks to En. Salim Arip and En. Muhamad Najib Fardos for
their assistance while conducting the field sampling and laboratory work.
My deepest gratitude also goes to the Sarawak Forestry Corporation at Sabal
Agroforestry Centre, most of all to En. Jimmy Ng Ting Seng for helping us during the
sampling period at Sabal.
I would also like to extend my gratitude to all my fellow friends especially Siti
Izyan Liyana Kamarol, Karyati Hanapi, Jessica Mary Emily Jem, Norazima Ali
Hossien, Norma Mamat, Haniza Razali, Frankie Lanying and Aizat Jaapar for sharing
their knowledge, moral support and friendship. Also, my special thanks to Muhammad
Noor Hisyam Abang Hashim for his faith and a never ending support.
Finally, my special and sincere thanks to my beloved parents, Mohd Sapawi
Jamain and Fauziah Bolhassan, and also to my sisters and brother for their love, support
and encouragement throughout this study.
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Diversity, Carbon Stock and Successional Pattern of Understory Herbaceous Plants in
Fallow Shifting Cultivation at Sabal Agroforestry Centre, Sarawak
ABSTRACT
Biodiversity has been known with its role in maintaining ecosystem functioning
thus have resulted in concern among land management professionals, the scientific
community and the public for the conservation of biodiversity. Large scale of forest
destruction may lead to the loss in biodiversity thus linked to the degradation of many
ecosystem services. Therefore, extensive research is needed to preserve the species
diversity within our forested ecosystems. This study was carried out at the Sabal
Agroforestry Centre, Sarawak to determine the floristic composition, above-ground
carbon stocks and early successional pattern of understory herbaceous vegetation
comparatively at five study sites, from different-aged fallow of shifting cultivation
represented by 1, 3, 5, 10 and 21 years fallow. A total of 50 quadrates (1m x 1m) were
randomly placed at each study site for floristic analysis while 20 quadrates were used
for carbon stocks and succession analysis. A total of 15,348 individuals were recorded,
comprising of 178 species in 145 genera of 70 families. The highest number of species
was at 1 year fallow (78 spp.) followed by 10 years fallow (68 spp.), 20 years fallow (49
spp.), 5 years fallow (45 spp.) and 3 years fallow (40 spp.). Based on Shannon-Wiener
diversity index (H’), both 1 year fallow and 10 years fallow showed the highest value
index (H’=3.24). It was observed that the 1 year fallow was diversely dominated by
herbaceous species (75.7%) while the 10 years fallow was diversely dominated by
woody species (67.6%). Therefore, the Sorensen index (SI) showed the lowest
similarity index between the 1 year fallow and 10 years fallow while the 3 years fallow
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and 5 years fallow had the highest similarity index. According to these similarity in
species composition, three groups of cluster were formed which indicates the 1 year
fallow in a single cluster, 3 years fallow and 5 years fallow in second cluster, while 10
years fallow and 20 years fallow in third cluster. The estimated above-ground carbon
stocks were highest at 1 year fallow (2.08 MgCha-1) followed by 20 years fallow (1.30
MgCha-1), 3 years fallow (1.10 MgCha-
1), 5 years fallow (0.73 MgCha-
1) and 10 years
fallow (0.43 MgCha-1). During seven months of succession period, each study sites
showed different pattern of species composition. The number of individual and species
increased significantly (P>0.05) throughout the observation period except for the 3
years fallow which showed no significant difference in the number of individual. This
research had showed that the study on understory herbaceous vegetation is essential for
a better understanding in species diversity since the species composition of understory
herbaceous vegetation are very responsive to the disturbance and may changed
considerably over time, thus reflected to the site conditions. Understory herbaceous
vegetation also play an important role to store carbon through their biomass.
Keywords: fallow forest, herbaceous, floristic composition, carbon stocks, succession
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Diversiti, Stock Karbon dan Corak Sesaran bagi Tumbuhan Herba Lantai Hutan di
Kawasan Tanah Terbiar Selepas Penanaman Pindah di Sekitar
Pusat Hutan Tani Sabal, Sarawak
ABSTRAK
Biodiversiti dikenali dengan peranannya dalam memelihara fungsi ekosistem
dan seterusnya menjadi perhatian dikalangan professional pengurusan tanah, golongan
saintifik serta orang awam untuk usaha pemuliharaan biodiversiti. Kemusnahan hutan
berskala besar boleh mengakibatkan kehilangan dalam biodiversiti dan seterusnya
menyumbang pada degradasi servis dalam ekosistem. Oleh itu, kajian yang meluas
diperlukan untuk memelihara spesies diversiti dalam ekosistem hutan kita. Satu kajian
telah dijalankan di sekitar Pusat Hutan Tani Sabal, Sarawak untuk menentukan
komposisi flora, menganggar stok karbon atas tanah serta corak awal sesaran bagi
tumbuhan herba lantai hutan di lima lokasi kajian tanah terbiar selepas penanaman
pindah yang berbeza umur iaitu tanah terbiar 1, 3, 5, 10 dan 20 tahun. Sejumlah 50
kuadrat diletakkan secara rawak di setiap lokasi kajian untuk analisis flora manakala
20 kuadrat digunakan untuk analisis karbon dan sesaran awal. Sebanyak 15,348
individu daripada 178 spesies, 145 genera dan 70 keluarga telah direkodkan. Tanah
terbiar 1 tahun mecatatkan bilangan spesies yang tertinggi (78 spp.) diikuti tanah
terbiar 10 tahun (68 spp.), tanah terbiar 20 tahun (49 spp.), tanah terbiar 5 tahun (45
spp.) dan tanah terbiar 3 tahun (40 spp.). Berdasarkan Shannon-Wiener diversiti indeks
(H’), kedua-dua tanah terbiar 1 tahun dan 10 tahun mencatatkan nilai indeks (H’) yang
tertinggi (H’=3.24). Melalui pemerhatian, tanah terbiar 1 tahun didominasi oleh
spesies herba (75.7%) manakala tanah terbiar 10 tahun didominasi oleh spesies anak
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pokok (67.6%). Oleh itu, Indeks Sorensen (SI) menunjukkannilai indeks kesamaan yang
paling rendah (SI= 0.15) adalah di antara tanah terbiar 1 tahun dengan tanah terbiar
10 tahun, manakala tanah terbiar 3 tahun dan tanah terbiar 5 tahun menunjukkan nilai
indeks kesamaan yang tertinggi (SI= 0.45). Berdasarkan pada kesamaan dalam
komposisi spesies, tiga kluster telah terbentuk menunjukkan tanah terbiar 1 tahun
berada dalam satu kluster, tanah terbiar 3 tahun dan 5 tahun dalam kluster kedua
manakala tanah terbiar 10 tahun dan 20 tahun dalam kluster ketiga. Anggaran stok
karbon atas tanah bagi tumbuhan herba lantai hutan adalah paling tinggi di tanah
terbiar 1 tahun (2.08 Mg C ha-1) diikuti tanah terbiar 20 tahun (1.30 Mg C ha-
1), tanah
terbiar 3 tahun, (1.10 Mg C ha-1), tanah terbiar 5 tahun (0.73 Mg C ha-
1) dan tanah
terbiar 10 tahun (0.43 Mg C ha-1). Sepanjang tempoh tujuh bulan kajian sesaran
dijalankan, setiap lokasi kajian menunjukkan corak komposisi spesies yang berbeza.
Nombor individu dan spesies telah meningkat dengan ketara (P>0.05) sepanjang
tempoh pemerhatian kecuali untuk tanah terbiar 3 tahun yang tidak menunjukkan
peningkatan yang ketara untuk nombor individu. Kajian ini telah menunjukkan bahawa
kajian terhadap tumbuhan herba lantai hutan adalah penting untuk kita lebih
memahami tentang spesies diversiti memandangkan komposisi spesies tumbuhan herba
lantai hutan sangat bertindak-balas pada sebarang gangguan dan akan berubah
dengan masa, sekaligus dapat menggambarkan keadaan sesuatu kawasan tersebut.
Tumbuhan herba lantai hutan juga memainkan peranan yang penting dalam
penyimpanan karbon melalui biomasnya.
Kata kunci: hutan terbiar, tumbuhan herba, komposisi flora, stok karbon, sesaran
vii
TABLE OF CONTENTS
Page
Declaration i
Acknowledgements ii
Abstract iii
Abstrak v
Table of contents vii
List of Tables x
List of Figures xii
List of Abbreviations xiv
Chapter 1 GENERAL INTRODUCTION
1.1 Introduction 1
1.2 Problem statement 3
1.3 Objectives 5
Chapter 2 LITERATURE REVIEW
2.1 Biodiversity 6
2.1.1 Species diversity, richness and evenness 7
2.2 Tropical rainforest 9
2.3 Shifting cultivation 11
2.3.1 Fallow period of shifting cultivation 14
2.4 Plant succession following disturbances 15
2.4.1 Understory herbaceous vegetation 17
2.4.2 Tree vegetation 18
2.5 Primary and secondary forest 20
2.5.1 Structural composition of secondary forest 21
2.5.2 Values of secondary forest 23
2.6 Forest biomass 24
2.6.1 Biomass and carbon storage estimation 25
2.7 Forest carbon 26
2.7.1 Deforestation and global climate change 27
2.7.2 Carbon sequestration and storage 28
2.8 Background of the Sabal Agroforestry Centre 31
viii
TABLE OF CONTENTS
Page
Chapter 3 MATERIALS AND METHODS
3.1 Study area 33
3.2 Data collection and analysis 35
3.2.1 Floristic composition and diversity 35
3.2.1.1 Diversity indices 36
3.2.1.2 Summed Dominance Ratio (SDR) 38
3.2.1.3 Similarity index 39
3.2.2 Above-ground carbon stocks 39
3.2.3 Early successional pattern 41
Chapter 4 RESULTS
4.1 Floristic composition and diversity of understory
herbaceous vegetation
42
4.1.1 Floristic composition 42
4.1.2 Species diversity, richness and evenness indices 61
4.1.3 Species dominancy 62
4.1.4 Similarity index and cluster analysis 82
4.2 Above-ground biomass and carbon stocks of
understory herbaceous vegetation
84
4.2.1 Allotment of the above-ground carbon stocks based
on plant growth habits
85
4.2.2 Above-ground carbon stocks estimated for each
species
87
4.3 Early successional pattern of understory herbaceous
vegetation
93
4.3.1 Number of plants for the first seven months after
the clear-cutting under different surrounding forest
conditions
93
4.3.2 Number of species for the first seven months after the
clear-cutting under different surrounding forest
conditions
101
Chapter 5 DISCUSSION
5.1 Floristic composition and diversity of understory
herbaceous vegetation
109
5.2 Above-ground biomass and carbon stocks of
understory herbaceous vegetation
119
5.3 Early successional pattern of understory herbaceous
vegetation
123
ix
TABLE OF CONTENTS
Page
Chapter 6 CONCLUSION AND RECOMMENDATION
6.1 Floristic composition and diversity of understory
herbaceous vegetation
127
6.2 Above-ground biomass and carbon stocks of
understory herbaceous vegetation
128
6.3 Early successional pattern of understory herbaceous
vegetation
129
References 131
Appendix A 154
Appendix B 162
Appendix C 165
x
LIST OF TABLES
Table Title Page
Table 3.1 Location of the study sites at Sabal. 34
Table 4.1 Floristic composition recorded within each study site at Sabal. 43
Table 4.2 Number of species recorded within each study site at Sabal. 45
Table 4.3 Distribution of families recorded within each study site at Sabal.
Total of genera, species and individual enumerated from the five
study sites at Sabal.
58
Table 4.4 Diversity indices for each study site at Sabal. 61
Table 4.5 Relative density (Rd), Relative frequency (Rf), Importance Value
Index (IVI) and Summed Dominance Ratio (SDR) for all species
enumerated from the five study sites at Sabal.
63
Table 4.6 Relative density (Rd), Relative frequency (Rf), Importance Value
Index (IVI) and Summed Dominance Ratio (SDR) for all species
recorded in the one year fallow at Sabal.
69
Table 4.7 Relative density (Rd), Relative frequency (Rf), Importance Value
Index (IVI) and Summed Dominance Ratio (SDR) for all species
recorded in the Temuda I at Sabal.
73
Table 4.8 Relative density (Rd), Relative frequency (Rf), Importance Value
Index (IVI) and Summed Dominance Ratio (SDR) for all species
recorded in the Temuda II at Sabal.
75
Table 4.9 Relative density (Rd), Relative frequency (Rf), Importance Value
Index (IVI) and Summed Dominance Ratio (SDR) for all species
recorded in the Belukar I at Sabal.
77
Table 4.10 Relative density (Rd), Relative frequency (Rf), Importance Value
Index (IVI) and Summed Dominance Ratio (SDR) for all species
recorded in the Belukar II at Sabal.
80
Table 4.11 Similarity index among the five study sites at Sabal. 82
Table 4.12 Total number of individual and total estimated above-ground
carbon stocks for each species recorded within the five study
sites at Sabal.
88
xi
LIST OF TABLES
Table Title Page
Table 4.13 Number of plants in 1 m2 during the first seven months of
succession after the clear-cutting.
95
Table 4.14 Number of species in 1m2 during the first seven months
of succession after the clear-cutting.
103
xii
LIST OF FIGURES
Figure Title Page
Figure 2.1 Location of three main regions of tropical rainforest, in Central
and South America, in West and Central Africa, and in South
East Asia.
10
Figure 2.2 Forest cover in Sarawak. 12
Figure 3.1 Map of the study area at Sabal. 34
Figure 4.1 Proportion of herbaceous and woody species within each study
site at Sabal.
55
Figure 4.2 Number of species based on the plant growth habit within each
study site at Sabal.
55
Figure 4.3 Number of species based on the phenological life span within
each study site at Sabal.
56
Figure 4.4 A dendrogram showing similarity relationships among the five
study sites. Hierarchical cluster analysis by Average linkage
(between groups) based on Euclidean distance method.
83
Figure 4.5 Above-ground carbon stocks of understory herbaceous
vegetation estimated for each study site at Sabal.
85
Figure 4.6 Estimation of above-ground carbon stocks for each study site
allotted based on the plant growth habit.
86
Figure 4.7 Number of plants in 1 m2 before the clear-cutting and after the
seven months of the clear-cutting. Mean with the same letter
are not significantly at α = 0.05 according to Tukey’s test.
97
Figure 4.8a Differences in growth habit before and after seven months of
clear-cutting done in Temuda I, in reference to the individual
number.
99
Figure 4.8b Differences in growth habit before and after seven months of
clear-cutting done in Temuda II, in reference to the individual
number.
99
Figure 4.8c Differences in growth habit before and after seven months of
clear-cutting done in Belukar II, in reference to the individual
number.
100
xiii
LIST OF FIGURES
Figure Title Page
Figure 4.9 Number of species in 1 m2 before the clear-cutting and after the
seven months of the clear-cutting. Mean with the same letter
are not significantly at α = 0.05 according to Tukey’s test.
105
Figure 4.10a Differences in growth habit before and after seven months of
clear-cutting done in Temuda I, in reference to the species
number.
107
Figure 4.10b Differences in growth habit before and after seven months of
clear-cutting done in Temuda II, in reference to the species
number.
107
Figure 4.10c Differences in growth habit before and after seven months of
clear-cutting done in Belukar II, in reference to the species
number.
108
xiv
LIST OF ABBREVIATIONS
% = Percent
α = Alpha
° C = Degree Celsius
ANOVA = Analysis Of Variance
BC = Before Christ
C = Carbon
ca. = Circa (approximately)
cm = Centimeter
CO2 = Carbon dioxide
dbh = Diameter breast height
gm-2
= Gram per meter square
H = Hydrogen
H’ = Shannon-Weiner diversity index
ha = Hectare
H2O = Water
IPCC = Intergovernmental Panel on Climate Change
J = Pielou’s evenness index
kg C ha-1
= Kilogram of Carbon per hectare
kg ha-1
= Kilogram per hectare
kg m-2
= Kilogram per meter square
km = Kilometer
km2 = kilometer square
xv
LIST OF ABBREVIATIONS
m = Meter
m2
= Meter square
mm = Milimeter
Mg C ha-1
= Megagram of Carbon per hectare
N = Nitrogen
O2 = Oxygen
Pg C = Petagram of Carbon
pH = Potential of Hydrogen
PVC = Polyvinyl chloride
R = Margalef’s richness index
SDR = Summed Dominance Ratio
SI = Sorensen’s similarity index
SPSS = Statistical Package for the Social Sciences
sq = Square
UNFCCC = United Nations Framework Convention on Climate Change
USDA = United States Department of Agriculture
1
CHAPTER 1
GENERAL INTRODUCTION
1.1 Introduction
Biodiversity derived from the contraction of the phrase “biological diversity”
covering many aspects of biological variation which comprises all life forms, ecosystems
and ecological processes. Biodiversity is a critical component of world ecosystem that
essential for human survival and economic well being as it regulates ecosystem function
and stability (Singh, 2002; Behera and Misra, 2006). Borneo has been acknowledged as one
of the world’s hotspots for plant biodiversity. As stated by Sarawak Forest Department
(2011), the flora of Borneo is conservatively estimated to harbour between 12, 000-15, 000
species of vascular plants, which are equals to 5-6% of the world total. Sarawak alone had
comprises more than 8, 000 species of vascular plants. According to Agriculture Statistics
in 1995 (State Planning Unit, 2000), there is about 94% of Sarawak total land use are
covered with forest which indicate that 63.7% of the forests are undisturbed while 30.4%
are secondary forest.
Shifting cultivation is frequently identified as one of the main causes of tropical
forest disturbance (Lawrence et al., 1998) and retrogression to secondary forest vegetation.
In Sarawak, shifting cultivation is a predominant method of agriculture and has been widely
practiced by groups of native peoples in order to produce various types of crops for their
income. Gupta and O’Toole (1986) stated that shifting cultivation occurs because of its
poor cropping management which consequently allows detrimental weed infestation and
2
declining soil fertility within two to three years after a field is cleared and planted with rice.
Farmers are then move to a new land because of the declining yield and left the previous
land to fallow which will be taken over by vigorous secondary herbaceous plant including
grasses and sedges. If such fallow land is left up to 10 years, it reverts to the secondary
forest type (Abebrese, 2002).
Succession is a natural recovery process of vegetation and ecosystems that occur
after forest disturbance (Mohizah, 2003). The common forest succession established after 1
year shifting cultivation is grassland which is mainly dominated by herbaceous plants.
Herbaceous plants are characteristically non-woody plants whose stem is soft and green,
rooted on the forest floor and typically low height. Typically, herbaceous communities at
recently disturbed site show high species richness which may persist during the first year of
succession due to high rates of species turnover (Valázquez and Goméz-Sal, 2009).
However, according to Ainie et al. (2007), as forest succession occurs continuously, the
diversity of these sun-loving plant species will decline rapidly as the impact of closed
canopy and competition among dominant species for soil resources.
The natural process of removing carbon dioxide (CO2) from the air and storing that
carbon in vegetation or in the soil is called carbon sequestration. Carbon sequestration is
thought to be a promising means for reducing atmospheric CO2, which is an important
greenhouse gaseous. Frelich et al. (2003) noted that the understory herbaceous plants play
an important role in a wide range of ecosystem functions primarily in energy flow and
nutrient cycling. It takes a significant part in carbon cycle by sequestered good amount of
CO2 particularly on the newly planted area where trees are only present at low densities.
As the photosynthesis process occur, the herbaceous plants sequester CO2 from atmosphere
3
through the carbon stored in their biomass which can be generate in a large amount for a
few years mainly in a newly opened site (Valázquez and Goméz-Sal, 2009).
This study was intended to enable the comparative study at different ages of fallows
on herbaceous diversity and their significant role in carbon stocks together with the early
successional pattern of understory herbaceous vegetation particularly in fallows of shifting
cultivation. This study was undertaken at the area of Sabal Agroforestry Centre, in the
Samarahan Division of Sarawak where shifting cultivation has been actively practiced by
local people in Sabal for many years.
1.2 Problem Statement
In Sabal, the local people are mostly populated by Iban villagers who carried out
shifting cultivation within the forest reserve even after their forceful eviction in 1984 (Nor
Rasidah, 2010), thus led to the retrogression of secondary forest. The Sabal Forest Reserve
comprises different-aged of regenerative secondary forest ranged from 1 year after
agricultural abandonment up to more than 20 years of secondary forest. It is expected that
different-aged of secondary forest may vary in their species composition. The herbaceous
layer are said to be the most sensitive in its response to harvest-mediated disturbance and
also has the highest species diversity (Gilliam, 2002). However, lack of documentation
about the herbaceous vegetation was done for this area especially on their floristic
composition and successional pattern. In view of the fact that shifting cultivation is a
widespread form of agricultural system practiced by the local people and resulted many of
4
fallow lands, it is important to understand the response and variation of herbaceous species
composition in different fallow ages.
Most forestry research related carbon studies have heavily focused either on trees or
forest soil while understory vegetation is not usually included in this analysis. Compared to
other components of forest ecosystems, the biomass of understory vegetation always
claimed to be small hence sometimes their presence was dismissed as negligible. However,
the understory herbaceous vegetation may actually play a significant role in many
ecosystem processes included the carbon cycle by sequestering CO2 (Gorte, 2007) from
atmosphere and rapid turnover at the biomass level (Muukkonen et al., 2006). Due to the
lack number of large trees that presence in the early age of fallow lands, the diverse and
fast-growing of understory herbaceous vegetation are seen to take a significant role for
carbon storage. Nevertheless, very little information can be gathered from past studies since
less attention was paid on the importance of understory herbaceous vegetation to store
carbon.
5
1.3 Objectives
The objectives of this research were as follows:
1. to determine the floristic composition and diversity of the understory herbaceous
vegetation comparatively in different-aged fallow of shifting cultivation (1, 3, 5,
10 and 20 years of fallow)
2. to estimate the amount of above-ground carbon stocks stored by understory
herbaceous vegetation in different-aged fallow of shifting cultivation
3. to determine the early successional pattern and initial floristic composition of
understory herbaceous vegetation in different-aged fallow of shifting cultivation
6
CHAPTER 2
LITERATURE REVIEW
2.1 Biodiversity
The biodiversity has been one of the central topics of ecology since many years. The
term of “biodiversity” formed as a contraction for “biological diversity” introduced during
the organization of a (United States) National Forum on Biodiversity in 1986 (Sarkar,
2006; Sarkar, 2010). In its broadest definition, biodiversity defined as the diversity of life in
all its forms and levels of organization including the ecological structures, functions and
processes at all of these levels (Roberts and Gilliam, 1995). Borneo, the largest island in the
Sundanic biogeographical subregion is reported as a centre for many genera and species of
the Malaysian flora, and also the home of the South East Asian Dipterocarps (Sidiyasa,
1999). The diversity of indices has become an attracting attention because of the surge
interest in biodiversity and the never ending quest for indicators of the status of the
environment (Heip et al., 1998).
Singh (2002) had noted the importance of biodiversity for human survival through
enormous direct economic benefits, indirect essential services of natural ecosystems and its
prominent role in modulating ecosystem function and stability. Rich in biodiversity favors
ecological stability whereas acceleration of species loss could lead to the unstable
ecosystem (Pokhriyal et al., 2009). The biodiversity and ecosystem function relationship in
term of productivity, nutrient cycling and storage, carbon sequestration, and stability to
perturbations have been studied broadly by researchers for many years and still are the
7
subject of debate (Ricotta, 2005). Therefore, conservation of biodiversity is aware not to be
as a set aside issue but rather one that requires significant actions throughout the forest
estate (Zhu et al., 2007).
In recent years, the loss in biodiversity has attracted the world attention. The loss
are believed as the impacts of forest management practices especially harvesting old growth
and short logging rotation which caused the diversity reduction in forest ecosystems (Hood,
2001). The loss in biodiversity is generally linked to the degradation of many ecosystem
services such as food and wood production, and self purification and nutrient cycling.
Therefore, due to the accelerating loss of species, national and global forestry organization
have recognized the need for biodiversity management (Roberts and Gilliam, 1995).
Attempting on these needs, the Society of American Foresters stated in 1991 had
recommended that “Professional foresters should manage forestlands to conserve, maintain,
or enhance the biological diversity of the region in which they work and, collectively, of
the nation and the earth” (Robbets and Gilliam 1995; Hood, 2001).
2.1.1 Species diversity, richness and evenness
Species diversity is a measure to the number of species in a community where each
species is weighted by its abundance (Alatalo, 1981). This function of measurement is
made up by combination of two principal components, richness and evenness (Bhatt and
Sanjit, 2005; Ejtehadi et al., 2007) which both are important aspects of biological
communities (Peters, 2004). Species diversity was the top list subject of biodiversity study
because it was the easiest to measure in the field (Ejtehadi et al., 2007).