Tree Diameter Distribution of a Community Forest at Kumpang Langgir, Sri Aman, Sarawak

TREE DIAMETER DISTRIBUTION OF A COMMUNITY FOREST AT KUMPANG LANGGIR, SRI AMAN, SARAWAK

Muhamad Kamal Bin Abdul Sani

Bachelor of Science with Honours (Plant Resource Science and Management) 2016

TREE DIAMETER DISTRIBUTION OF A COMMUNITY FOREST AT KUMPANG LANGGIR, SRI AMAN, SARAWAK.

MUHAMAD KAMAL BIN ABDUL SANI (42349)

The project is submitted in partial fulfilment of the requirement for the degree of Bachelor of

Science with Honours

(Plant Resource Science and Management)

Faculty of Resource Science and Technology UNIVERSITI MALAYSIA SARAWAK 2016

APPROVAL SHEET

Name of Candidate : Muhamad Kamal Bin Abdul Sani

Title of Dissertation : Tree Diameter Distribution of a Community Forest at Kumpang Langgir, Sri Aman, Sarawak.

………………………………

(Prof. Dr. Ismail bin Jusoh)

Supervisor

…………………………......

(Dr. Freddy Yeo Kuok San)

Coordinator

Plant Resource Science and Management Department of Plant Science and Environmental Ecology Faculty of Resource Science and Technology Universiti Malaysia Sarawak

DECLARATION

I hereby declare that this Final Year Project 2016 is based on my original work except for quotations and citations, which have been duly declared that it has not been or concurrently submitted for any degrees at UNIMAS or other istitutions of higher education.

______

Muhamad Kamal Bin Abdul Sani (42349)

Plant Resource Science and Management Department of Plant Science and Environmental Ecology Faculty of Resource Science and Technology Universiti Malaysia Sarawak

III

ACKNOWLEDGEMENT

First of all, Alhamdulillah because I can complete my final year project. Thanks to Allah for providing me with wisdom and endurance throughout the process of completing this project. I would like to express my deepest appreciation to my supervisor. Prof. Dr. Ismail bin Jusoh, for his guidance, support, advice and help in completing my final year project. There are so many knowledge and experiences I gained from him. Besides, I would like to thank also to our field sampling team, which consisted of one local Iban elder and Plant Science and Environmental

Ecology Department staffs; En. Mohd. Rizan, En. Sekudan and En. Salim during field sampling in Kumpang Langgir, Lubok Antu, Sri Aman, Sarawak.

A special thanks to my FYP mate especially Muhammad Syafuan bin Ismail and Bryan Pastdy anak Layang whom had helped me in completing my FYP. Last but not least, thanks to my family for their care and support in completion of this study.

Tree Diameter Distribution of a Community Forest at Kumpang Langgir, Sri Aman, Sarawak

Muhamad Kamal Bin Abdul Sani

Plant Science and Management Resource Programme Faculty of Resource Science and Technology Universiti Malaysia Sarawak

ABSTRACT:

Tree diameter distribution provides information for forest assessment. Community forest is the forest that were established for the importance of the local community and have research value. However, there are lack of forestry data of community forest at Kumpang Langgir, Sri Aman, Sarawak. The objective of this study was to determine the diameter distribution of the community forest. Twenty-five plots of 20m x 20m were laid on four different transects over 20 ha study area. Tree diameter at breast height (DBH) of 5 cm and above were measured and identified up to species level. DBH recorded were grouped into classes with interval of 5 cm. Number of family, genus, species and trees for each DBH classes were analysed. Basal area, Importance Value index (IVi) and Morisita’s index were also determined. There were 15 DBH classes recorded. Graph of relationship between number of family, genus, species and stems according to each DBH class shows reverse J-shaped. Indicates that the forest regeneration is healthy. In term of genus, Dipterocarpaceae and Myrtaceae ranked top in 5 different DBH classes each. Graph of total basal area for each DBH class shows skewed to the left bell-shaped pattern. For IVi value, Syzygium antisepticum (Myrtaceae) is the most dominance species in 7 out of 10 DBH class. Myrtaceae species dominated the forest compared with Dipterocarpaceae species. Morisita’s index shows smaller DBH classes (5<10 cm and 10<15 cm) were dispersed randomly and larger DBH classes (15<20 cm and above) were dispersed uniformly.

Key words: diameter distribution; community forest at Kumpang Langgir; diameter at breast height (DBH) classes; Importance Value index (IVi); Syzygium antisepticum.

ABSTRAK:

Taburan diameter pokok memberikan maklumat untuk penilaian hutan. Hutan komuniti adalah hutan yang diwartakan untuk kepentingan komuniti setempat dan mempunyai nilai kajian.. Walau bagaimanapun, terdapat kekurangan data perhutanan untuk hutan komuniti di Kumpang Langgir, Lubok Antu, Sarawak. Tujuan kajian ini adalah untuk mengenalpasti taburan diameter di hutan komuniti tersebut. Dua puluh lima plot bersaiz 20m x 20m telah dibina pada empat transek berbeza di atas kawasan kajian seluas 20 ha. Pokok berdiameter aras dada (DBH) 5 cm dan keatas diukur dan dikenalpasti hingga ke tahap spesies. DBH yang direkod dikelaskan dengan selang 5 cm. Bilangan famili, genus, spesies dan pokok dianalisis. Luas pangkal, indeks nilai kepentingan (IVi) dan Indeks Morisita juga dianalisis. Terdapat 15 kelas DBH yang telah direkod. Graf hubungan antara jumlah famili, genus, species dan pokok menunjukkan bentuk J terbalik. Menunjukkan pertumbuhan semula hutan tersebut adalah sihat. Untuk famili, Dipterocarpaceae and Myrtaceae masing-masing berada di kedudukan teratas untuk 5 kelas DBH berlainan. Graf jumlah luas pangkal keseluruhan untuk setiap kelas DBH menunjukkan bentuk loceng condong ke kiri. Untuk nilai IVi, Syzygium antisepticum (Myrtaceae) adalah spesies paling dominan di dalam 7 daripada 10 kelas DBH. Indeks Morisita menunjukkan kelas DBH yang lebih kecil (5<10 cm dan 10<15 cm) tersebar secara rawak manakala DBH lebih besar (15<20 cm dan keatas) tersebar secara seragam.

Kata kunci: taburan diameter; hutan komuniti di Kumpang Langgir; kelas diameter aras dada (DBH); indeks nilai kepentingan (IVi); Syzygium antisepticum.

TABLE OF CONTENTS

Title page I

Approval sheet II

Declaration III

Acknowledgement IV

Abstract V

Table of contents VI

List of abbreviations IX

List of figures X

List of tables XI

CHAPTER ONE: INTRODUCTION 1

CHAPTER TWO: LITERATURE REVIEW 3

2.1 Undisturbed forest 3

2.2 Forest stand structure 4

2.2.1 Age of the forest stands 4

2.3 Species composition in tropical rain forest 5

2.4 Tree size measurement 6

2.4.1 Diameter measurement of tree 6

2.5 Tree size distribution 7

2.5.1 Diameter distribution of tree 7

CHAPTER THREE: MATERIALS AND METHODS 9

3.1 Study site 9

3.2 Field sampling 10

3.3 Data analyses 12

3.3.1 Basal Area of the Tree 12

3.3.2 Ranking of family by genus, species and trees 12

3.3.3 Importance Value Index (IVi) 13

3.3.4 Morisita Index 14

CHAPTER FOUR: RESULTS 15

4.1 Distribution of diameter at breast height (DBH) 15

4.2 Basal area by DBH class 20

4.3 Family composition 21

4.4 Species dominance by DBH class 22

4.5 Spatial distribution by DBH class 24

CHAPTER FIVE: DISCUSSION 25

5.1 Tree distribution 25

5.2 Floristic composition by DBH class 26

5.3 Basal area 27

5.4 Species dominance 28

5.5 Spatial distribution 29

CHAPTER SIX: CONCLUSION 30

REFERENCES 31

Appendix I 35

Appendix II 36

Appendix III 37

Appendix IV 38

Appendix V 39

Appendix VI 39

VII

Appendix VII 40

Appendix VIII 40

Appendix IX 41

Appendix X 41

Appendix XI 41

Appendix XII 42

Appendix XIII 46

Appendix XIV 50

Appendix XV 53

Appendix XVI 56

Appendix XVII 58

Appendix XVIII 59

Appendix XIX 60

Appendix XX 61

Appendix XXI 62

Appendix XXII 63

VIII

LIST OF ABBREVIATIONS

DBH Diameter at breast height ha hectare m metre cm centimetre km kilometre

IVi Importance Value index

Id Morisita index

LIST OF FIGURES

Page

Figure 1 Map showing study area that is located 30 km by road from 9 Engkilili.

Figure 2 Map shows location of four transects. 10

Figure 3 Measuring diameter at breast height (DBH) using diameter tape. 11

Figure 4 Plotting were done with compass and measuring tape. 11

Figure 5 Number of family againts DBH classes (cm) of a community forest 16 at Kumpang Langgir, Lubok Antu, Sri Aman, Sarawak.

Figure 6 Number of genus againts DBH classes (cm) of a community forest 17 at Kumpang Langgir, Lubok Antu, Sri Aman, Sarawak.

Figure 7 Number of species againts DBH classes (cm) of a community 18 forest at Kumpang Langgir, Lubok Antu, Sri Aman, Sarawak.

Figure 8 Number of stem againts DBH classes (cm) of a community forest 19 at Kumpang Langgir, Lubok Antu, Sri Aman, Sarawak.

Figure 9 Total basal area (m2) againts DBH classes (cm) of a community 20 forest at Kumpang Langgir, Lubok Antu, Sri Aman, Sarawak

LIST OF TABLES

Page

Table 1 Number of family, genera and species by DBH classes (cm) in a 15 community forest at Kumpang Langgir, Lubok Antu, Sri Aman, Sarawak

Table 2 Top family in terms of number of genus, species and stems in all 21 DBH classes.

Table 3 Most dominant species recorded for DBH (cm) of 5<10, 10<15, 23 15<20, 20<25, 25<30, 30<35, 35<40, 40<45, 45<50 and 50<55 of a community forest at Kumpang Langgir, Lubok Antu, Sri Aman.

Table 4 Morisita index of dispersion, Id 24

CHAPTER ONE

INTRODUCTION

The island of Borneo is the third largest island in the world. There are 2 states and 1 federal territory of Malaysia in Borneo. Sarawak is one of the state and the largest with total area of

451, 865 km2 (Diway & Chai Paul, 2004). Tropical rain forests in Malaysia are highly diverse with different species of plants, insects and animals. Many types of forest can be found such as highland, lowland and mixed dipterocarp forest, peat swamp forest, kerangas forest and montane forest.

Structure of plant and animal communities in the forest influenced significantly by disturbances. According to Lalfakawma et al. (2009), the disturbance that occurred in the system are naturally or because of anthropogenic activities. Besides, disturbances also important to maintain community composition. Two example of forest disturbance are when trees are felled or effect of forest fire due to human activities for tree harvesting and for conversion to agricultural land.

Forest measurement is very important in order to manage forest. The main importance of the forest measurement is to supply quantitative or numerical data (Avery &

Burkhart, 1994). The data obtained is helpful for forest managers in making a decision on how to manage and sustain the forest. According to West (2009), tree size measurement is very important to help in understanding of the forest growth and development. Several parameters used in measurement such as age, diameter over or under the bark, cross- sectional area (calculated from diameter), length or height, volume and form or shape

(Philip, 1994).

According to West (2009), the most important in forestry measurement is the stem diameter because of its simple method and most common used. Normally, the tree diameter is measured as DBH or diameter at breast height, which is 1.3 m from ground by using caliper or diameter tape (West, 2009). From the diameter measurement data, the distribution of the tree diameter can be determined. Forest stand diameter structure describe widely by diameter distribution.

However, there are lack of data sets information from community forest in Kumpang

Langgir, Lubok Antu due to lack of empirical data study had been conducted. Forestry depends on the data from the forest especially the diameter distributions to identify the size and age of the trees. Thus, the diameter distribution data should be studied and collected as it can be used to assess the growth and development of regrowth forest. On the other hand, forest managers need the data from the community forest of Kumpang Langgir, Lubok Antu especially the tree diameter to determine the health status of the forest.

The aim of this study was to determine the (i) diameter distribution of tree species in a community forest and (ii) to describe and compare the species dominance in the forest stand structure between diameter size classes as well as to determine the diversity of the species in relation to tree size distribution.

CHAPTER TWO

LITERATURE REVIEW

2.1 Undisturbed Forest

Lalfakawma et al. (2009) studied the community composition and tree population structure in undisturbed and disturbed tropical semi-evergreen forest stands of North-East

India. Their study showed that the undisturbed stand consists higher diversity and species richness as well as higher density and frequency as compared to disturbed forest. Besides,

Lalfakawma et al. (2009) stated that based on their results, disturbance have more negative impacts by destroying the climax assemblages and disturbed the system’s stability.

Moreover, Lalfakawma et al. (2009) confirms the findings by Rao et al. (1990) that there are declining of species diversity and abundance from undisturbed to the disturbed stands.

In addition, there are possibility for certain pioneer species of disturbed stands to be found in the undisturbed stands. Lalfakawma et al. (2009) discussed that pioneer species such as Schima wallichii was found in the undisturbed stands due to similarity of both stands.

Schima wallichii was enhanced to invades and establishes it species in the undisturbed stands. Harrison et al. (2006) described that biodiversity ‘hot spots’ rich in native species have more chance to be invaded by the exotic species due to similar resource availability of both sites.

2.2 Forest Stand Structure

Forest stand structure is defined by Oliver and Larson (1990) as “the physical and temporal distribution of trees in stand”. It included determining the species distribution description, tree size or age of the tree. While, stand structure simply described by Kimmins

(1996) and Franklin et al. (1981) as plant’s vertical and horizontal organisations. Porter and

Stone (1998) state that measurement that easily done from ground level such as diameter at breast height is the bases of most forest stand structure descriptors. LaFrankie and

Manokaran (1990) studies on floristic composition of Pasoh Forest Reserve shows that by using the basal area of the forest stands concludes that there are consistent stand structure between primary lowland forests in the Malay Peninsular and within large scale permanent plot at Pasoh Forest Reserve.

2.2.1 Age of the Forest Stands

West (2009) mentioned that there are two types of forest stand based on the age, which are even-aged and uneven-aged. Avery and Burkhart (1994) defined even-aged stand as the stand that have only 10-20 years differences of ages. Even-aged stand is the stand that have same time of natural regeneration or planting time (West, 2009). Avery and Burkhart

(1994) describes uneven-aged stand as the stand that had its ages exceed 20-30 years from the even-aged stand age limits. Besides, uneven-aged forest is also referred as the stand that have three or more age classes. According to West (2009), uneven-aged stand occurred in most native forests. In addition, Krug and Lorimer (1983) mentioned in their studies that the third type of age structure might occurred. The third type is the stand that are not or equally prominent have several age classes.

2.3 Floristic Composition in Tropical Rain forest

Tropical rain forest also known as evergreen forest or evergreen moist tropical forests

(Borota, 1991). South America, Africa and the Far East are the three major blocks of tropical rain forest in the world (Wong, 1997). Tropical rain forest have very high species diversity that made it the singular most distinctive feature of the forest (Morley, 2000). Tropical rain forest consists several of forest types such as montane forest, mixed dipterocarp forest and kerangas forest. In kerangas forest or tropical heath forest, various interesting plant species grows such as insectivorous sundews, pitcher plant and epiphytic shrubs such as

Hydnophytum spp. (Wong, 1997). Besides, bigger trees such as majestic conifer, Agathis borneensis also grows on different type of kerangas forest that surrounded by peat swamps.

The variety and abundance of Dipterocarpaceae family occurred mostly in Far East tropical rainforest (Wong, 1997). According to Borota (1991), there are high number of various evergreen tree species, shrubs, herbaceous and woody lianas grows among closely compact tall trees in Asian tropical rainforests. Besides, there also various species of ferns, epiphytes, and grasses. Light demanding tree species can grow up to height of 50 to 60 metres with diameter of 150-350 cm in tropical rain forest such as Koompasia excelsa, measured 84 metre in Borneo. Forest in Borneo is estimated to cover more than 60% of the island. According to MacKinnon et al. (1996), they estimated that there are 10,000 to 15,000 flowering plant’s species occurred in the island. While, Ashton (1982) stated that there at least 3,000 species of trees, including 267 species of dipterocarps of which 58% of are endemics.

2.4 Tree Size Measurement

Tree size measurement also called tree mensuration. According to Philip (1994), mensuration is a measurement of length, mass and time. For the forest, mensuration helps to understand the growth and development of forest, determining the quantity of tree products human wants and ensuring the forest is in an appropriate management (West, 2009). The measuring unit depends on the parameter used. For example, Philip (1994) stated that diameter measurement was recorded in cm or mm by using a calliper.

2.4.1 Diameter Measurement of Tree

Diameter measurement of a tree or known as diameter breast height (DBH) is the measurement of tree stem diameter at breast height (West, 2009). This definition was supported by Mohammadalizadeh et al. (2009) study where they measured the diameter of the tree at breast height, DBH in uneven-aged forest. The breast height defined by West

(2009) as the height that 1.3m above the ground from the base of the tree. The other countries such as America used imperial unit where 1.3m is equal to 4 feet 6 inch. The highest ground level at the base of the tree will be chosen if the tree is growing on slope ground. The reason why breast height used for the measurement of tree diameter is because as the decreasing of stem diameter from the base to stem (West, 2009).

West (2009) also points out that the stem diameter gave more information for the data analysis compared with the other diameter part of the tree. There are three arguments stated; (i) stem diameter is correlated with the other parameter that difficult to measure such as wood volume in the stem and weight or biomass of the tree; (ii) the money value of the logs producing from the tree and; (iii) how well the tree species growing in different tree stands or species.

2.5 Tree Size Distribution

On the other hand, tree size distribution defined as the number of individuals that fall within each tree size class that vary considerably in forests (Hao et al., 2009). Many factors affect the variation of tree size distribution in the forest. Hao et al. (2009) listed several factors such as competition for natural resources, patterns of regeneration, disturbance, environmental condition and irregular or seasonal climatic events. Tree size distributions also often used to assess the effect of disturbance within the forests (Hett & Loucks, 1976;

Denslow, 1995; Coomes & Allen, 2007).

2.5.1 Diameter Distribution of Tree

The study of tree size distribution especially the diameter in forests is important for forester as it can be used to evaluate the forest resources and plan the schedule for the future silvicultural treatment (Nanos & Montero, 2002). According to Rubin and Manion (2006), the possibility for the current population of larger trees to be replaced by the small trees can be indicated by the diameter distributions. Kia Lashaki et al. (2011) discussed that diameter distribution study also can determine the diameter structure of the forest and modelling the growth. According to Hough (1932), the plotting of diameter distribution must be done separately for individual species from small homogenous stands to give a reasonable indication of age structure. Diameter distribution of trees also important for growth research and stands yield in a specific stand (Burnham, 2002). Besides, population structure of forests often represents by using diameter distribution of trees (Newton & Smith, 1988).

In forestry, diameter distribution has always played a crucial role. Garcia (1991) stated that the integration of data acquisition, forecasting of growth, planning on how product be utilized and managing the information can be done with the help of advancement of computer technology and software packages based on distribution. Commonly, “probability density function” and the list of tree diameters determine the stand diameter distribution. He stated that the list of diameter measurement can be used to specify the diameter distribution for the stand or the tree samples. Garcia (1991) also notes that the locations of the tree on the ground, spatial interactions of the trees and the environment affects the diameter.

Zheng and Zhou (2010) stated that there two types of key distribution applied generally. Firstly, normal or nearly normal for even-aged forest. Second, the regressive descending model for uneven-aged forests. Besides, they mentioned in their study that the evenness and growth status for stands can be described by diameter distribution.

CHAPTER THREE MATERIALS AND METHODS

3.1 Study site

This study was conducted at Kumpang Langgir in Lubok Antu. Lubok Antu is located in Sri Aman division of Sarawak. The study site is approximately 30 km by road from Engkilili town (Figure 1). Sampling site is within Kumpang Langgir is locally known as Bukit Kerangas. The specific sampling site known as ‘pulau’, few small patches of mature primary forest left. The sampling site is partially disturbed forest but mostly undisturbed.

The natural vegetation is lowland dipterocarp rainforest and the surrounding areas is dominated by secondary forests and farmland at various stages. Sampling site has a steep to moderately undulating terrain, ranging from about 190 to 300 metres of altitude. It was formed by two different substrates series, which are intermediate on tertiary sedimentary and the highest on quaternary sedimentary. The mean annual rainfall is 3,450 mm and the mean air temperature is 27 °C. The soils are red-yellow inceptisols or ultisols.

Figure 1. Map showing study area that is located 30 km by road from Engkilili. Retrieved from Google Earth (2016).

3.2 Field Sampling

The sampling site is approximately within an area of 20 ha by plotting using GPS

(Figure 2). Four transect lines were established. Transect 1 length was 400 m with 6 plots.

Next, Transect 2 consists of 6 plots with 400 m length. Transect 3 is the longest transect, 600 m with 8 plots. Lastly, Transect 4 – 400 m with 5 plots. Each plot was laid at approximately

50-70 m apart, depending on accessibility.

Transect 1

Transect 2

Transect 3

Transect 4

Figure 2. Map shows location of four transects. Retrieved from Google Earth (2016).

Overall, 25 plots of 20m x 20m were established which make up a total of one ha area sampled (Figure 3). Trees with DBH of 5 cm and above were recorded and identified.

The tree diameter was measured at 1.3m or breast height from the ground using diameter tape (Figure 4). The tree species was identified up to species level. Local name was also recorded.

Figure 3. Plotting were done with compass and measuring tape.

Figure 4. Measuring diameter at breast height (DBH) using diameter tape.

3.3 Data Analyses

The collected data were processed and transferred to a spreadsheet. Species identification were done in the field and for positive identification of scientific name were done in UNIMAS. The data of the tree diameter was grouped into 15 diameter classes which are 5 < 10 cm, 10 < 15 cm, 15 < 20 cm, 20 < 25 cm, 25 < 30 cm, 30 < 35 cm, 35 < 40 cm,

40 < 45 cm, 45 < 50 cm, 50 < 55 cm, 55 < 60 cm, 60 < 65 cm, 70 < 75 cm, 75 < 80 cm and

80 < 85 cm. The number of families, genera, species and trees for each DBH class were counted and analysed. Software used for the data processing and analysing is Microsoft

Excel.

3.3.1 Basal Area of the Tree

The basal area was computed from the DBH data. Philip (1994) stated that basal area or BA is the total cross-sectional area at breast height summed over all the trees at stand.

Basal area is the common amount of an area occupied by tree stems. The formula using to calculate the basal area is as following:

BA= 0.00007854 D2 (m2)

BA = basal area (m2)

Where, D = diameter at breast height

3.3.2 Ranking of Family by Genus, Species and Trees

For each DBH class, the family was ranked in the terms of number of genus, species and trees. Only the top 10 was listed in the results in the form of table. Complete listing is provided in Appendix.