GROWTH OF SHOREA MACROPHYLLA (DE VRIESE) ASHTON UNDER LINE PLANTING AT GUNUNG APENG FOREST RESERVE SARAWAK
‘AFIFAH BINTI HUSSEIN
Bachelor of Science with Honours (Plant Resource Science and Management) 2015
Growth of Shorea macrophylla (de Vriese) Ashton under Line Planting at Gunung Apeng Forest Reserve Sarawak
‘Afifah Binti Hussein
34726
This project report is submitted in partial fulfilment of the requirements for the Degree of Bachelor of Science with Honours
(Plant Resource Science and Management)
Supervisor: Prof Dr. Hamsawi Sani
Plant Resource Science and Management
Department of Plant Science and Environmental Ecology
Faculty of Resource Science and Technology
Universiti Malaysia Sarawak
2015
APPROVAL SHEET
Name of candidate : ‘Afifah Binti Hussein
Matric number : 34726
Title of dissertation : Growth of Shorea macrophylla Under Line Planting at Gunung Apeng Forest Reserve Sarawak
______
(PROF. DR. HAMSAWI SANI)
Supervisor
______
(DR. REBICCA EDWARD)
Coordinator
Plant Resource Science and Management Programme
Department of Plant Science and Environmental Ecology
Faculty of Resource Science and Technology
Universiti Malaysia Sarawak
ACKNOWLEDGEMENT
First and foremost, my praise to Allah, The Almighty God for giving me strength, good health and mind for me to face all the challenges and tasks from beginning up to the last time in completing my research project.
I would like to express my sincere gratitude to my supervisor, Prof. Dr. Hamsawi Sani for his guidance, patience, motivation and immense knowledge in helping me in any time of research and writing of this final year project report. Greatest gratitude also dedicate to other lectures especially Dr. Effendi Wasli and UNIMAS staff for help and guide me in my research study. Thanks also to Japan-Malaysia Association (JMA) as this project is under this association with collaboration of Sarawak Forestry Department.
My sincere thanks also goes to my friends who helped me a lot especially in collecting data during our field trip to Gunung Apeng Forest Reserve, Serian. Not to forget also to master students, Mugunthan Perumal and Ho Soo Ying who teach and guide me to understand better. I had a very nice experience working with my colleagues and master students.
I would like also to thank my parents, Mr. Hussein Ismail and Mdm. Suraini Abd Latiff as well as my family for the support and encouragement that had been given through my entire life. They had been my strength to live better as a degree student in UNIMAS.
Above ground, many thanks to everyone who help me out directly or indirectly in completing my final year project for this undergraduate degree. May God repay all your kindness.
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DECLARATION
I hereby declare that the Final Year Project Report is based on my originality work except for quotations and citations, which have been acknowledged. I also declare that it has not previously or concurrently submitted for any degree qualification at Universiti Malaysia
Sarawak, UNIMAS or other of higher learning institute.
______
(‘AFIFAH BINTI HUSSEIN)
34726
Plant Resource Science and Management Programme
Department of Plant Science and Environmental Ecology
Faculty of Resource Science and Technology
Universiti Malaysia Sarawak
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TABLE OF CONTENTS
TITLE Page No
ACKNOWLEDGEMENT…………………………………………………… i
DECLARATION……………………………..……………………………… ii
TABLE OF CONTENTS……………………………………………………. iii
LIST OF ABBREVIATIONS……………………………………………….. v
LIST OF TABLES………………………………………………………….... vi
LIST OF FIGURES………………………………………………………….. vii
LIST OF APPENDICES…………………………………………………….. ix
ABSTRACT/ABSTRAK…………………………………………………….. x
CHAPTER 1: INTRODUCTION…………………………………………… 1
CHAPTER 2: LITERATURE REVIEW………………………………….. 4 2.1 Current Status of Forest Plantation Development……………….…….. 5 2.2 Shorea macrophylla (de Vriese) P. S. Ashton…………………..……... 6 2.2.1 General description ………………………………...... 6 2.2.2 Taxonomic classification ……………………………………...... 8 2.2.3 Vernacular names ………………………………………………. 9 2.2.4 Habitat/site requirement …………………………...... 9 2.2.5 Economic importance …………………………………..……..... 9 2.3 Enrichment Planting…………………………………………………… 10 2.3.1 Line planting……………………………………………….……. 11 2.3.2 Gap planting ……………………………………………………. 12 2.3.3 Under canopy …………………………………………………… 13 2.4 Silvicultural Treatment……………………………………………….... 14 2.4.1 Line slashing …………………………………………………..... 16 2.4.2 Girdling ...…………………………………………...... 16 2.5 Factors Affecting Success of Forest Planting………………………….. 17 2.6 Environmental Factors Affecting Growth Performance……………….. 18
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2.6.1 Water (precipitation) ……………………………...... 18 2.6.2 Light …………………..……………………………….……….. 19 2.6.3 Temperature …………………………………………………….. 19
CHAPTER 3: MATERIALS AND METHODS…………………………... 20 3.1 Research Site…………………………………………………………. 20 3.2 Research layout………………………………………………………. 22 3.3 Line Planting Treatments…………………………………………….. 23 3.4 Parameter Assessment………………………………………………... 26 3.5 Statistical Analysis…………………………………………………… 27
CHAPTER 4: RESULTS AND DISCUSSIONS…………………………… 28 4.1 Growth Assessment on Shorea macrophylla……………………………. 28 4.1.1 Survival percentage of Shore macrophylla……………………….. 28 4.1.2 Tree total height and diameter of Shorea macrophylla……...... 31 4.1.3 MAIH and MAID of Shorea macrophylla………………………... 35 4.2 Light Intensity Assessment…………………………………………... 39 4.3 Potential Commercial Plant Species…………………………………. 42 4.3.1 Potential commercial species and family………...…………….. 42 4.3.2 Growth of potential commercial species…………………...... 42 4.3.3 Crown layout by potential commercial species……...…………. 46
CHAPTER 5: CONCLUSION AND RECOMMENDATION….………… 52
CHAPTER 6: REFERENCES...... 54
APPENDICES...... 59
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LIST OF ABBREVIATIONS
ANOVA Analysis of Variance cm centimeter
GAFR Gunung Apeng Forest Reserve ht Tree total height
IUCN International Union for Conservation of Nature
JMA Japan-Malaysia Association m meter
MAID Mean annual increment of diameter
MAIH Mean annual increment of height
NGO Non-government Organization
PFE Permanent forest estate
T1 Treatment 1
T2 Treatment 2
T3 Treatment 3
UNIMAS Universiti Malaysia Sarawak
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LIST OF TABLES
Table no Title Page
Table 3.1 Species trees that had been girdled in Treatment 2 25
Table 4.1 Chi-squared comparison between treatments with response of 29 survivability
Table 4.2 Comparison mean of tree total height of Shorea macrophylla 31 between three treatments over age
Table 4.3 Comparison mean of tree total height of Shorea macrophylla 32 between three treatments over age
Table 4.4 Comparison MAI of 2 years old Shorea macrophylla between three 35 treatments
Table 4.5 Comparison percentage of light intensity between treatments 39
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LIST OF FIGURES
Figure no Title Page
Figure 2.1 Gunung Apeng Forest Reserve 5
Figure 2.2 Shorea macrophylla seedling 7
Figure 2.3 Shorea macrophylla’s leaves 7
Figure 2.4 Shorea macrophylla’s stipules 7
Figure 2.5 Shorea macrophylla’s flowers 7
Figure 3.1 Permanent Forest Reserve in Sarawak 21
Figure 3.2 Forest Plantation Map 21
Figure 3.3 Layout of three treatments with six subplots in study plot 22
Figure 3.4 Layout of three treatments with six subplots in study plot 23
Figure 3.5 Treatment 1 (line slashing) 24
Figure 3.6 Treatment 2 (line slashing and girdling) 24
Figure 3.7 Treatment 3 (control) 24
Figure 3.8 Girdled tree and tree felling after being girdled 25
Figure 4.1 Survival percentage of Shorea macrophylla between treatments 29
Figure 4.2 Mean of tree total height of Shorea macrophylla over age 32
Figure 4.3 Mean of diameter of Shorea macrophylla over age 33
Figure 4.4 MAIH of Shorea macrophylla 36
Figure 4.5 MAID of Shorea macrophylla 36
Figure 4.6 Light intensity between treatment in study plot 40
Figure 4.7 Families of commercial species in study plot 43
Figure 4.8 Number of commercial species in study plot 43
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Figure 4.9 Tree total height of potential commercial species 46
Figure 4.10 Diameter of potential commercial species 47
Figure 4.11 Crown layout from top view of potential commercial species 49
Figure 4.12 Estimation of percentage area covered by crown of potential commercial 50 species
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LIST OF APPENDICES
Appendix No Title Page
Appendix 1 Location of study site in Gunung Apeng Forest Reserve 59
Appendix 2 Main layout of study site (100 m x 50 m) 60
Appendix 3 Inventory form (Shorea macrophylla’s growth) 61
Appendix 4 Inventory form (potential commercial species) 62
Appendix 5 Raw data of growth of Shorea macrophylla in three treatments 63
Appendix 6 Chi-squared test for survivability of Shorea macrophylla between 70 treatments
Appendix 7 Descriptive statistic for diameter and height of Shorea macrophylla 71
Appendix 8 One-way ANOVA of diameter of Shorea macrophylla 72
Appendix 9 One-way ANOVA of height of Shorea macrophylla 73
Appendix 10 One-way ANOVA of MAID and MAIH of Shorea macrophylla 74
Appendix 11 Descriptive statistic and one-way ANOVA of light intensity in study 75 plot
Appendix 12 Potential commercial species in study plot 76
Appendix 13 Crown layout sketching of potential commercial species 78
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Growth of Shorea macrophylla (de Vriese) Ashton under Line Planting at Gunung Apeng Forest Reserve Sarawak
‘Afifah Binti Hussein
Plant Resource Science and Management Programme Department of Plant Science and Environmental Ecology Faculty of Resource Science and Technology Universiti Malaysia Sarawak
ABSTRACT This study aimed to measure the growth performance of Shorea macrophylla trees that were planted in 2012 by line planting method at Gunung Apeng Forest Reserve Sarawak. This species is well-known for its valuable timber, major source of illipe nuts and other benefits that had been discovered yet. However, S. macrophylla had listed under IUCN Red List as a threaten species. The objectives of the study were i) to determine the best requirement of light intensity for S. macrophylla to grow well, ii) to determine effect growth or survival percentage of S. macrophylla under different treatments and, iii) to evaluate the potential of commercial species in the study area. S. macrophylla planted under line planting method with 100 m length and 50 m width with three different silvicultural treatments which are control, line slashing and line slashing with tree girdling. Each treatment has two subplots and every subplots have 30 trees. Each tree was measured its diameter at 30 cm above ground, tree total height and light intensity under each tree. The results indicated that the line slashing treatment has the highest survival percentage, diameter and tree total height among these three treatments. Apart from that, all potential commercial species within study plot was enumerated and crown layout is determines to indicate the light intensity percentage in the study plot. It was shown that Alstonia scholaris is most dominant species and Treatment 2 (line slashing and girdling) has highest percentage of area covered by commercial plant’s crown.
Keyword: Shorea macrophylla, silvicultural treatment, growth performance, light intensity, commercial species
ABSTRAK Kajian in bertujuan menilai prestasi pertumbuhan pokok Shorea macrophylla yang ditanam pada tahun 2012 dengan menggunakan cara penanaman secara sejajar di Hutan Simpan Gunung Apeng, Sarawak. Species ini sangat dikenali dengan hasil kayu yang bernilai, sumber utama kekacang minyak dan kelebihan lain yang belum dijumpai. Namun begitu, S macrophylla telah disenaraikan dibawah Senarai Merah IUCN sebagai spesies yang terancam. Objektif kajian ini adalah untuk i) mengetahui keperluan keamatan cahaya yang terbaik untuk S. macrophylla membesar dengan baik; ii) untuk mengetahui kesan tumbesaran dan peratus kelangsungan hidup S. macrophylla dibawah rawatan yang berlainan; iii) untuk menilai potensi sepsis komersial di dalam kawasan kajian. S. macrophylla ditanam menggunakan penanaman secara sejajar dengan 100 m panjang dan 50 m lebar dan mempunyai tiga rawatan silvikultur yang berlainan iaitu kawalan, libasan sejajar serta libasan sejajar dan pengeratan. Setiap rawatan mempunyai dua subplot dan setiap subplot mempunyai 30 pokok. Setiap pokok diukur diameter 30 cm dari tanah, jumlah tinggi pokok dan keamatan cahaya dibawah setiap pokok. Keputusan menunjukkan rawatan libasan sejajar mempunyai peratus kelangsungan hidup, diameter dan jumlah ketinggian pokok yang paling tinggi diantara tiga rawatan tersebut. Selain itu, semua species berpotensi komersial di dalam plot kajian dihitung dan peta puncak pokok dilakar untuk menentukan peratus keamatan cahaya di dalam plot kajian. Hasil menunjukkan Alstonia scholaris adalah spesis yang paling menonjol dan Rawatan 2 (libasan sejajar dan pengeratan) mempunyai peratusan paling tinggi kawasan yang ditutupi kemuncak pokok komersial.
Kata kunci: Shorea macrophylla, rawatan silvikultur, hasil tumbesaran, keamatan cahaya, spesis komersia
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CHAPTER 1: INTRODUCTION
The study of Shorea macrophylla growth’s assessment at Gunung Apeng Forest Reserve
Sarawak had started since 2012. The observation and data was conducted on growth performance of S. macrophylla in the forest and analyzed the factors that may affect its growth.
The high demands from industrial sector and domestic needs to make nature resources as their variety of products. Specifically wood products make the forest become degraded and decrease its biodiversity especially due to overexploitation or illegal logging activities.
Dipterocarpaceae family is well-known for its high-demand market especially in timber production such as S. macrophylla. To meet these demands, many trees had to be cut down and thus forests become degraded. In addition to that, nature forest’s sustainability become worst with the natural phenomenon that can occur such as forest burning and heavy erosion due to open land (Sakurai, 2006).
Fortunately, the awareness of importance in managing forest in proper way has increase among the community regardless of government, Non-Government Organization (NGO) and publics in international and national levels. Many methods on forest plantation regeneration management were formulated and recommended. For example, Sarawak become the good model in the application of proper forest management practices through the effort of minimize residual damage during harvesting and to avoid soil become degraded such as in Gunung Apeng Forest Reserve and Balai Ringin Protected Forest.
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Reforestation has many different purposes depending on the situation, either for rehabilitation of impacted forest landscape, timber productions through plantation of fast- growing commercial species, revegetate disturbed area or for storage carbon (Kikkawa,
2006). According to Kikkawa (2006) again, there are criteria that should to be assessed to do reforestation sites for biodiversity. The six criteria that should be examined are (1) species heterogeneous; (2) affiliation of species excluded; (3) uncommon or endanger species; (4) vast number of protected species; (5) denseness of species migrant; (6) and type of vicinity. Based on these criteria, replanting of Shorea macrophylla meet three criteria which are species diversity where S. macrophylla has less diverse since it is only endemic to Malaysia; clarify as threaten species in IUCN since it is very valuable for timber production; and neglegation of protected species that has very little of efforts to protect this species but people still overexploit it for economic importance.
Silvicultural treatment is one of the practices that had been applied on Shorea macrophylla species. Silviculture is about tree’s agriculture which involve the ways to grow, maximize growth and influence trees compositions in order to meet the demands (Kelvin, &
Campbell, 2014). One of the techniques that has been applied widely especially for Shorea species is enrichment planting. According to The Dictionary of Forestry (2008), enrichment planting is introducing interested species to degraded or secondary forest without cutting off other valuable species that already exist in the area. Enrichment planting is the planting of valuable tree species in cleared lines or blocks, imitate forest opening when tall tree falls down, provide soil protection from erosion and ease forest development. Thus, in this study area the purposes of enrichment planting are to conserve
Shorea species and to increase timber production’s sustainability (Widiyatno et al., 2013).
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Carbon dioxide, sunlight and water are the important elements for plant to carry out photosynthesis. Amongst these elements, this study will focus more on the factor of sunlight. There are three principles of light that had been mentioned by University of
Arizona (1998) which are light duration, light quality and light quantity. Light quantity varies by season and refer to sunlight’s intensity. Photosynthesis of plant can be more efficient when enough light intensity received by plant. However different species has different tolerance to light. Meanwhile, Shorea macrophylla is shade tolerant species.
However, in order to reduce reforestation cost, Matsune et al., (2006) had suggested 1) suitable planting method selection for particular species to increase survival rate and reduce planting density, and 2) control light conditions received especially in seedling growth stage. Besides that, in order to do reforestation or replanting of threaten species, some areas need to be cleared. Thus, preexisting trees will be removed and this will decrease the diversity of species in the forest especially in dipterocarp forest where many valuable species are not yet to be discovered. In order to maintain and rehabilitate those dipterocarp forest and for sustainable timber production, it is important to understand the characteristics of Shorea species as it can be manipulated and grown to an optimum level.
(Sasaki, 2006). Thus, this research need to be done to determine the optimal light intensity required for Shorea macrophylla to grow well and identify the valuable species present in the Gunung Apeng Forest Reserve, Sarawak.
The objectives of this study are i) to determine the effect of silvicultural treatment in tree growth; ii) to evaluate the change and effect of light intensity after silvicultural treatment; iii) enumerate the commercial species added ingrowth in study plot.
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CHAPTER 2: LITERATURE REVIEW
2.1 Current Status of Forest Plantation Development
In 1920, forest plantation in Malaysia especially in Sarawak had developed initially with exotic species. According to Appanah and Abd Razak (1998), the exotic species must have potential end-use and environmental function of plantation before established for forest plantation.
The exotic species that firstly established are Shorea (meranti), Durio zibenthinus (durian) and Azadirachta excelsa (sentang) under Forest Rehabilitation Programme. Forest rehabilition programme is to that make the waste land to something good and usable for habitation and cultivation. Initially, nineteen hectares in Semenggoh Forest Reserve had being used to plant Engkabang that is well-known for its illipe nuts’ benefit and now is important as timber product. Forest land use in Sarawak had been categorised as three types which are Permanent Forest Estate (PFE), Totally Protected Areas (TPA), and
Stateland Forest (Ahmad Ashrin, 2010). Gunung Apeng Forest Reserve is one of the example of PFE which is used for sustainable forest production. Thus, forest plantation is one of the ways to sustain timber production and alternative to Forest Rehabilitation
Programme. Former minister of Plantation Industries and Commodities, Datuk Peter Chin
Fah Kui was stated that future aim in Sarawak plantation especially for public sector such as Sarawak Forestry is to replant an average of 24,000 hectares while for private sector is
70,000 ha a year to achieve one million hectares by year 2020.
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By year 2010, under Japan-Malaysia Friendship Program, 309 hectare with 120,800 seedlings of exotic species were planted in Balai Ringin Protected Forest and 225 hectares with 90,000 seedlings planted in Gunung Apeng Forest Reserve (Ahmad Ashrin, 2010).
While in 2012, a group from Mitsubishi Corporation, Forestry Department of Sarawak and
UNIMAS collaborated for tree planting activity at Gunung Apeng Forest Reserve. Total number of 123 400 seedlings of Engkabang jantong, Kapur bukit and fruit trees had been planted in area of 308.50 hectares. Meanwhile, 1.5 hectares was specifically for 600 seedlings of Engkabang jantong were planted (Forestry Department Sarawak, 2012).
Figure 2.1 showed the study plot of Shorea macrophylla that had been planted on 24th
November 2012.
Figure 2.1 Gunung Apeng Forest Reserve
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2.2 Shorea macrophylla (de Vriese) P. S. Ashton
2.2.1 General Description
Shorea macrophylla is a medium fast-growing species and has been listed as threaten species in IUCN Red List. This species is totally protected species and very endemic to
Borneo island.
According to Rudjiman and Adriyanti (2002), they had described the Shorea macrophylla as an evergreen, thick, dense tree and has open oblong to hemispherical crown. While, the bole is often distorted and the branches can be low down as possible. The trunk is straight or leaning and can grow up to 50 m tall, 130 cm diameter and buttress up to 2 m height.
The bark surface is pale-grey to brown, smooth when young, scaling in large, irregular pieces and has shallowly scroll-marked surface beneath. The outer bark is thin, brown and hard while the inner bark is about 7 mm thick color in pale-yellow brown. The sapwood is pale-yellow, heartwood in blackish and soft. It will exudate resin when being slashed
(Figure 2.2).
The characteristics of leaf is alternate, stout, has petiolate, about 2-3.5 cm, sometimes kneed, glabrous or with sparse grey-brown short indumentum, blade elliptical and coriaceous (Figure 2.3). Stipule is elliptical or triangular, persistent and obtuse at apex
(Figure 2.4). Flower has pale pink petals of 15 stamens and fruiting calyx with 5 wings; 3 longs and 2 shorts (Figure 2.5). The seed is recalcitrant and take 2-3 days to germinate under natural condition. The fruit is well-known as illipe nuts and has some commercial importance (Lim et al., 2011).
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Figure 2.2 Shorea macrophylla seedling Figure 2.3 Shorea macrophylla’s leaves
Figure 2.4 Shorea macrophylla’s stipules Figure 2.5 Shorea macrophylla’s flowers
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2.2.2 Taxonomic Classification
Domain : Eukaryota
Kingdom : Plantae
Subkingdom : Virdaeplantae
Phylum : Tracheophyta
Subphylum : Euphyllophytina
Infraphylum : Radiatopses
Class : Spermatopsida
Subclass : Rosidae
Superoder : Malvanae
Order : Malvales
Family : Dipterocarpaceae
Subfamily : Dipterocarpoideae
Tribe : Shoreae
Genus : Shorea
Specific epithet : macrophylla
Botanical name : Shorea macrophylla (de Vr.) Ashton
(Stang, 2014)
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2.2.3 Vernacular Names
English: light red Meranti. Malaysia: engkabang jantong (Iban), engkabang gading
(Sarawak), kawang jantung (Sabah). Brunei: kawang jantong. Indonesia: awing katalok, tengkawang buah (East Kalimantan), tengkawang hantelok (Kalimantan) (Soerianegara &
Lemmen, 1994).
2.2.4 Habitat/Site Requirement
It is usually found at mixed dipterocarp forest, along the river banks and prefer fertile alluvium soil that has high retention water ability (Appanah & Weinland, 1993). It can tolerate with slopes which usually at clay hills below 600 m above the sea level. This species needs shade during early years and not suitable for open planting method (Appanah
& Weinland, 1993).
2.2.5 Economic Importance
The species has very light and brittle hardwood. The color of sapwood and heartwood is similar and hard to differentiate (Appanah & Weinland, 1993). The timber is in pale cream and have pinkish tinge sometimes. The wood grain is interlocked and its texture is moderately coarse and even (Lim et al., 2011). The end-use of this species can be furniture, interior finishing, paneling, plywood and veneer.
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2.3 Enrichment Planting Methods
Enrichment planting method is one of the technique of forest rehabilition. It is the method of introduce specific valuable species into degraded forest or secondary dipterocarp forest without cutting of other valuable species that existed in the area. According to Keefe
(2008), enrichment planting can be as device to give some long-term value to forest. In his paper, the effect of tree growth performance on enrichment planting were assess based on two types of scales which are large industrial and family farm planting. He also mentioned the advantage of enrichment planting is able produces multiple timber harvest. However, it requires much cost such as for labor, equipment, training, site preparation and transportation. Due to this, planting treatment methods were suggested to reduce the management cost which influence by species and site condition.
Enrichment planting also affects the light condition received by treated plants (Sasaki,
2006). Most of dipterocarp species is shade-tolerant species and do not grow under high light intensity especially at seedling stage such as Shorea macrophylla and Shorea leprosula. However, there are some species that can tolerate under high light intensity and stress tolerance such as Anthoshorea, Vatica and Anisoptera (Sasaki, 2006).
A study done by Matsune et al. (2006) showed the growth difference of 2 ½ years old trees between Shorea leprosula and Shorea pauciflora. They found that S. leprosula showed greater growth in gap planting and under canopy planting while S. pauciflora showed greater growth in line planting and under canopy. They also found out that open area planting is not suitable for Shorea sp seedlings as they exposed to high light intensity.
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Matsune et al. (2006) had cited the work done by Carini and co-workers concluded that each species have different growth and survival rate in different silvicultural techniques.
The differences of growth performance are caused by different physiological response to environment for each plant species.
2.3.1 Line Planting
According to Sovu et al (2010), line planting is define as passage or cutting line in forest site and has specific width. While, the studied seedlings were planted in fixed distance along the line. Factors that greatly influence growth of seedlings in line planting are line width, line direction (Syafiqah Syahira, 2014) and height of dominant plant surrounds
(Sovu et al., 2010) since these will influence light intensity in the area. All non- commercial species that exist such as small trees, shrubs and undergrowth are removed before planting.
Studied done by Garcia and Falck (2005) at Tapah Hill Forest Reserve showed that different time for girdling affect the growth of Dipterocarp seedlings with width of planting site is between 0.9 to 1.8 m by using line planting treatment. They concluded that line width, time of canopy opening are some factors that affect the growth of studied species. The line planting technique has widely used since more dipterocarp species can adapt under this environment. Besides that, it can reduce decreasing of soil properties and death rate of trees that causes by water stress and heat.
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