2. Evaluation of Selected Physical and Mechanical Properties of Multiple Leader Acacia crassicarpa A.Cunn.Ex.Benth and Acacia mangium Willd. Nor Aini Ab. Shukor, Paridah Md. Tahir, Mohd. Faisal Jaafar and Zainal Abidin Ismail INTROP/Faculty of Forestry INTROP/Faculty of Forestry Universiti Putra Malaysia Universiti Putra Malaysia 43400 Serdang, Selangor, 43400 Serdang, Selangor, MALAYSIA. MALAYSIA.Tel:6-03-89467186 anishukor@yahoo.com anishukor@yahoo.com

3. INTRODUCTION Forest tree plantation in tropics - exotic species. e.g. pines and acacias.Forest tree plantation in tropics - exotic species. e.g. pines and acacias. Species trial results - useful information on:Species trial results - useful information on: (a) performance (a) performance (b) adaptability (b) adaptability (c) species-site interaction…BUT (c) species-site interaction…BUT Required research to understand, physiology, genetic and wood properties.Required research to understand, physiology, genetic and wood properties. Extent of Acacia plantation in Asia – review - Turnbull (1998);Extent of Acacia plantation in Asia – review - Turnbull (1998);

4. Many national and international provenance trials of A. mangium and A. crassicarpa conducted – different regions. e.g. China, Indonesia, Malaysia, Thailand, and Vietnam.Many national and international provenance trials of A. mangium and A. crassicarpa conducted – different regions. e.g. China, Indonesia, Malaysia, Thailand, and Vietnam. Results of introductions and genetic improvement especially in Malaysia and Thailand revealed some impediments and limitations in :Results of introductions and genetic improvement especially in Malaysia and Thailand revealed some impediments and limitations in : (a) growth - incidence of heartrot (a) growth - incidence of heartrot (b) Tree form - develop multiple trunk and epicormic (b) Tree form - develop multiple trunk and epicormic branching/multiple leader (ML) formation branching/multiple leader (ML) formation ML – most limiting factor for log production ofML – most limiting factor for log production of desirable size – 15 years rotation desirable size – 15 years rotation ML – having more than 1 leader/stem from the baseML – having more than 1 leader/stem from the base

5. Figure 1: Various classes of ML formation ML class 1ML class 4ML class 2ML class 3

6. Actual factors causing and variation of ML - not known. It may be due to genetics and site environmental conditions (Srivastava,1993). Others related it to: (a) cultural practices (b) genetic variation within genotypes and families Standard sivilcultural practice in Malaysia of ML - singling i.e. retaining one stem per tree and cutting the rest. Done as early as 4 - 6 months after out planting - before formation of heartwood.

7. Formation of ML is undesirable – lower the quality of timber – no report on quality of wood properties of ML sources. Singled wood usually not utilized or as alternative raw material in composite manufacturing (Kong, 1998).

8. OBJECTIVES To evaluate selected mechanical and physical properties of the multiple leadered trees from different genotypes of Acacia crassicarpa and Acacia mangium.

9. MATERIALS AND METHODS Seeds of A. crassicarpa Wood specimens for 5 yr-old of 2 species; i) A. mangium i) A. mangium ii) A. crassicarpa involving : 1. Provenances from 2 regions i.e a) 4 from Queensland (QLD) a) 4 from Queensland (QLD) i) i) Claudie River, ii) Chillie Beach, iii) Captain Billy road, iv) Russel Gap & CK b) 3 from Papua New Guinea (PNG) b) 3 from Papua New Guinea (PNG) i) ii) i) Bensbach WP, ii) Bimadebu WP iii) SW of Boset WPAND 2. ML classes i.e a) ML2 (with two leaders) b) ML3 (with more than two leaders). Seeds of A. mangium

10. PNG Figure 2 : Selected provenances used in this study. QLD Bimadebum WP Bensbach WP Captain Billy road Russel Gap & CK Claudie River Chillie Beach SW of Boset WP

11. Table 1: Provenances (genotypes) of A. crassicarpa and A. mangium Multiple Leader RegionProvenance Latitude (°S) Longitude (°E) Altitude No. of Trees No. of Samples 2 PNG Bensbach WP05° 03’141° 17’25m410 Bimadebum WP03° 08’142° 03’40m310 QLD Claudie River12° 48’143° 18’20m710 Chillie Beach12° 38’143° 24’03m310 3 PNG Bensbach WP05° 03’141° 17’25m110 Bimadebum WP03° 08’142° 03’40m110 QLD Claudie River12° 48’143° 18’20m110 Chillie Beach12° 38’143° 24’03m110 A. crassicarpa 2 PNG Bensbach WP85° 03’141° 17’25m210 SW of Boset WP71° 07’141° 05’100m310 QLD Captain Billy road11°41’142° 42’100m210 Russel Gap & CK11° 52’145° 19’60m 2 * 3 PNG Bensbach WP85° 03’141° 17’25m210 SW of Boset WP71° 07’141° 05’100m210 QLD Captain Billy road11°41’142° 42’100m210 Russel Gap & CK11° 52’145° 19’60m2 * A. mangium Note * - Provenance Russel Gap & CK was excluded due insufficient sample size

12. ML 2ML 3 With two leadersWith more than two leaders Two leadersFour leadersThree leaders Figure 3: Wood specimens obtained from two ML classes.

13. STUDY LOCATION Established at the How Swee Estate, Kuala Lipis, Pahang (Lat: 4 0 20.5’N, Long: 101 0 55.5’E, Alt: 91.50 m asl.) Mean annual temperature: 27 0 C. Annual rainfall: 2,211 mm. Soil description: Deep, brownish yellow - yellowish brown fine sandy loam, weak to moderate medium - fine sub angular blocky structures.

14. FIELD TRIAL Figure 4: Location of the Study Site in Kuala Lipis, Pahang where the specimens were taken A trial of A. mangium A trial of A. crassicarpa

15. The samples tested according to BS373:1957-Testing of Small Clear Specimen of Timber for : i) - i) Physical - specific gravity (SG), radial and tangential shrinkages. ii) Mechanical - modulus of elasticity (MOE) and modulus of rupture (MOR) properties. Data - subjected to ANOVA of the different sources using SAS version 6.12 software. Mean values - compared and separated by Duncan’s New Multiple Range Test. Schematic diagram of sample used in this study. Sample tested for static bending

16. RESULTS AND DISCUSSIONS

17. Table 2: Summary of physical and mechanical properties of A. crassicarpa and A. mangium Species Source of Variation PhysicalMechanical Specific Gravity Radial Shrinkage Tangential Shrinkage Static Bending MOE (N/mm 2 ) Static Bending MOR (N/mm 2 ) F Value Acacia crassicarpa Multiple Leader 367.57*732.63*1002.47*482.02*630.2* Provenance0.73 ns 0.15 ns 0.41 ns 1.73 ns 1.12 ns Acacia mangium Multiple Leader 0.11 ns 0.83 ns 0.54 ns 0.15 ns Provenance10.78*7.16*16.85*16.43*6.85* * Significant at p<0.05. ns - not significant - A. crassicarpa: significant differences between ML - A. mangium: significant differences between provenance

18. Figure 5: Mean Value of SG, Radial and Tangential Shrinkages, MOE and MOR between ML2 and ML3 of A. crassicarpa PhysicalMechanical a a a a a b b b b b ML2ML3ML2ML3

19. Significant differences of physical and mechanical properties between ML classes BUT not between provenances ML2 produced higher mean values in terms of specific gravity, MOE and MOR compared to ML3 because ML2 produced bigger diameter stem size – infering larger heartwood portion, higher amount of wood substance to cell cavity and thus higher specific gravity (SG) SG is closely related to wood mechanical properties (Zhang, 1997). A. crassicarpa

20. However, ML2 showed lower shrinkage (radial and tangential) than ML3 – thus growth stress is more pronounced in ML 3 compared to ML 2. ML 3 experience more stress as the result of more injuries during the singling operation compared to ML 2. (assumption: When no. of leaders removed increased, injuries increased)

21. Figure 6: Specific Gravity, Radial and Tangential Shrinkages, MOE and MOR of different Provenances of A. mangium. MechanicalPhysical

22. A. mangium Significant differences of physical and mechanical properties between provenances classes BUT not between ML classes Provenance from Bensbach WP perform the best while SW of Boset WP - poorest in terms of physical and mechanical properties Different provenances/genotypes expressed different capabilities in terms of growth and physiological function including wood properties.

23. Table 3 : Physical properties of important plantation species SPECIESSPECIFIC GRAVITY RADIAL SHRINKAGE (%) TANGENTIAL SHRINKAGE (%) REFERENCES Acacia crassicarpa0.471.523.08Abel (1997) *A. crassicarpa (ML2)0.451.403.59Present study *A. crassicarpa (ML3)0.482.895.83Present study Acacia mangium0.511.953.65Hazani (1994) *A. mangium (MLa)0.453.073.69Present study *A. mangium (MLb)0.463.694.43Present study *A. mangium (MLc)0.442.713.25Present study Swietenia macrophylla0.541.402.20Haslett et. al. (1991) Tectona grandis0.70 1.10Haslett et. al. (1991) Gmelina arborea0.491.202.30Haslett et. al. (1991) Hevea brasiliensis0.65NA Razali & Hamami (1992) Note:MLa - Multiple leader (Captain Billy Road)ML2 - Multiple leader with 2 leaders MLb - Multiple leader (Bensbach WP)ML3 - Multiple leader with > 2 leaders MLc - Multiple leader (SW of Boset WP)

24. Table 4 : Mechanical properties of important plantation species SPECIESMOE N/mm 2 MOR N/mm 2 REFERENCES Acacia crassicarpa6499.4366.69Abel (1997) *A. crassicarpa (ML2)9858.489.63Present study *A. crassicarpa (ML3)7557.760.4Present study Acacia mangium990874.5Wang (1989) *A. mangium (MLa)867672.2Present study *A. mangium (MLb)1016583.0Present study *A. mangium (MLc)719752.4Present study Swietenia macrophylla9483.3691.77Haslett et. al. (1991) Tectona grandis12134.62120.33Haslett et. al. (1991) Gmelina arborea8769.5681.58Haslett et. al. (1991) Hevea brasiliensis924066Razali & Hamami (1992) Note:MLa - Multiple leader (Captain Billy Road)ML2 - Multiple leader with 2 leaders MLb - Multiple leader (Bensbach WP)ML3 - Multiple leader with > 2 leaders MLc - Multiple leader (SW of Boset WP)

25. CONCLUSION Different species responded differently on the physical & mechanical properties based on ML and provenances differences. Strength is associated with ML classes i.e. the lesser the number of stems, the better the physical and mechanical properties. Based on the MOE values obtained, it is assumed that such wood sources would have similar utilization to selected important plantation species such as Hevea.