Acacia mangium Plantation in Sarawak and its Wood Quality

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1 Abstract mangium Plantation in Sarawak and its Wood Quality Ismail Jusoh and Nur Syazni Adam Faculty of Resource Science and Technology, Universiti Malaysia Sarawak, Kota Samarahan, Sarawak, Plantation forestry is becoming increasingly significant in Sarawak. The Sarawak Government is committed to establish commercial plantations and, by the year 2020, one million hectares of its land is targeted to be planted with forest trees. This is essential as the future of timber processing industries in Sarawak is dependent on the availability of logs. The objectives of this paper were to examine the status of mangium as the major plantation species in Sarawak and asses its wood quality by evaluating its inherent wood properties. To date about 289,816 ha plantation forests have been established in Sarawak and mangium make up 74% of the planted area. New planting material of A. mangium has been introduced and planted in Sarawak that acquire many desirable properties such as faster growth, straighter bole, less tapering and resistant to heart-rot. The new breeds are known as hybrid, which is meant to produce wood and second-generation mangium also known as A. mangium superbulk planted for fibre production to be used especially for making fibreboard. Results showed that basic density of seven years old hybrid and second-generation mangium was 472 kg/m 3 and 336 kg/m 3, respectively. The strength properties of second-generation mangium significantly low compared to hybrid. The average fibre length and fibre wall thickness in the hybrid were 962 µm and 2.21 µm, respectively and were found to be greater than in second-generation mangiun (901 µm and 1.88 µm). Fibre diameter (17.16 µm) and fibre lumen diameter (12.75 µm) in hybrid were smaller than that of second-generation mangium. hybrid was more resistance to Coptotermes sp. attack than second-generation mangium. Laboratory soil block test showed that hybrid and second-generation mangium were moderately durable timbers. This study indicated that marked differences in wood properties and qualities between hybrid and second-generation mangium. Further study is required to accurately assess the wood properties of both acacias because of variation effects due to locations, growth characteristics and silvicultural practices. Key words: Forest plantation; hybrid; second-generation mangiun; wood properties Introduction Sarawak is committed to establish one million hectares of commercial plantations by the year 2020 (PERKASA, 2009). This is in line with the effort to meet the current and future raw materials demand from the timber industry as well as to conserve the natural forest. Currently, the State Government has issued 43 Licenses for Planted Forests (LPF) covering 1.4 million hectares of net planting areas (PERKASA, 2009). At present, about 290,000 hectares of commercial plantation forests have been planted with mainly mangium. In order to achieve the one million hectare target, the remaining 710,000 hectares need to be 1

2 planted at a rate of 88,750 hectares per year in the next 8 years. This is essential as the future of processing industries in Sarawak is dependent on the availability of resource. However A. mangium plantation faced few setbacks. They appeared to be susceptible to heartrot damage (Hashim et al. 1990) and it s suitability for sawlog and peeler log remained unsatisfactory (Weinland and Zuhaidi 1990). Considerable effort has been made to overcome these setbacks such as planting acacia hybrid and new clones. Recently two new breed have been introduced in some plantations in Sarawak which are mangium x auriculiformis hybrid and second-generation mangium. mangium x auriculiformis hybrid commonly known as acacia hybrid, appear to acquire many desirable properties such as faster growth, straighter bole, less tapering and more resistant to heart rot. To maintain its superior characteristics hybrids was mass propagated by cuttings. mangium superbulk or acacia superbulk as it commonly called is an improved a second-generation tree as a result of tree improvement program. It has superior performance in terms of growth rate, high volume, stem form and resistant to heart rot and it s propagated by seeds. The future utilization of both hybrids and A. mangium superbulk depend on their wood quality. The suitability of hybrid and A. mangium superbulk for any end-use products is dictated by wood properties. It is frequently assumed that improvement in growth rate and characteristics will also result in improvements in the wood properties. Little is known about the wood properties and qualities of acacia hybrid and acacia superbulk. The objectives of this were to examine the growing stock of mangium plantation in Sarawak and compare the physical and mechanical properties of seven years old acacia superbulk and acacia hybrid. Materials and Methods Data source The forest plantation data employed in this paper have largely been supplied by Forest Department Sarawak. The data were used to estimate the acacia growing stock for Sarawak. Sampling and sample preparation Materials for this study was obtained from approximately 7-year-old stand of hybrid, A. mangium superbulk, mangium (PNG provenance) and auriculiformis (PNG provenance) planted in BTSSSB area located at Similajau, 75 km from Bintulu. auriculiformis and mangium were selected from adjacent provenance trial plots. Six trees were felled and each tree was first marked according to DBH, 50%, 70% and 90% of bole length. The bole length was taken from stump to 10 cm top diameter. From each height level one 1.2 m long bolt was cut. Two quarter-sawn flitch of 5 cm thick was cut through the centre from bark to bark from each bolt and subsequently conditioned to air-dry in a room for subsequent analyses. Physical and mechanical properties Each quarter-sawn flitch was ripped to produce true radial, tangential and longitudinal sample of 2.5 cm x 2.5 cm x 10.0 cm. The samples were first saturated in water and then weighed 2

3 and green volumes were determined by water immersion method. Basic density for each sample was computed on an oven dry weight-green volume basis. Static bending and compression parallel to grain were determined according to British Standard Institution 373:1957 (BSI. 1957). Fibre morphology Portions of the quarter-sawn flitch were ripped to obtain sample cubes of 1 cm x 1cm x 1 cm. The cubes were soften using 4% ethylenediamine (Berlyn and Miksche 1976). Transverse sections of approximately 18 to 20 micrometer (µm) were used to measure fibre diameter, fibre wall thickness, and fibre lumen diameter. Wood slivers parallel to grain were macerated in 1:2 (v/v) mixture of glacial acetic acid and 30% of hydrogen peroxide. Fifty unbroken fibres were selected for determination of fibre length. Natural durability Determination of natural durability acacia wood was conducted using decay test and termite resistance test. Wood decay test was done using laboratory soil block test according to American Society for Testing and Materials (ASTM) Standard D (1998). Fungi used in this study were Trametes versicolor, Schizophyllum commune and Rigidoporus microporus. All of the fungi strains were obtained from the division of Forest Products Technology, Forest Research Institute of Malaysia (FRIM). Weight losses of the samples blocks were calculated from the difference of the weight of the blocks before and after incubation. The termite test resistance test was conducted according to Japan Wood Preserving Association (JWPA) standard 11(1) Ten sample blocks from each species were randomly selected and weighed prior to termite resistance test. One hundred and fifty workers and fifty soldiers of Coptotermes sp were introduced into each container. Results and Discussion Planted forests in Sarawak The Sarawak Government is committed to establish 1 million ha of planted forests by year To achieve this, the state government enacted the Forest (Planted Forests) Rules, 1997 gazetted in 23 January The establishment of commercial planted forests is to be carried out by private companies issued with Licenses for Planted Forest (LPF). As of 2009, 43 LPF had been issued (PERKASA, 2009). The total area of planted forest in Sarawak as of 2011 is estimated to be 289,816 hectares. The planted forest area by year is presented in Figure 1. There was an annual increase in planted area from However, there was a marked reduction in planting activities in The largest area planted was in 2006 with 47,939 ha in total. The rate of planting began to decrease from 2007 to The major species planted is listed in Table 1 with acacia accounted for 74% of the total area planted. To achieve the one million hectare target, the remaining 710,000 hectares need to be planted at a rate of 88,750 hectares per year in the next 8 years. This is essential as the future of processing industries in Sarawak is dependent on the availability of resource. The average annual planting rate was 19, 321 ha and this accounts for only 22% or one-fifth of the planting rate required to achieve the one million ha target (Fig. 1). The largest area planted so 3

4 far was in 2006 and that was only 54% or one-half of the planting rate required. As such a concerted effort must be made by the LPF holders and the government must reaffirm its commitment to achieve the one-million-hectare target by Area palnted (ha) ,321 ha annual average Year Figure 1. Annual area of planted forest in Sarawak Table 1. Total planted area by species in Sarawak as of 2011 Species Batai Kelampayan Eucalyptus Others Total planted (%) Physical properties Mean values of basic density, tangential, radial and volumetric shrinkages are given in Table 2. hybrid recorded the highest basic density and A. mangium superbulk mean basic density was significantly lowest among the species. Basic density of hybrid and mangium did not differ significantly at 5% level. The result indicate that although the basic density of hybrid was between their parental species basic densities but statistically its basic density did not differ with mangium. 4

5 Table 2. Physical properties of hybrid mangium (superbulk), mangium and auriculiformis. Species Basic density (kg/m 3 ) hybrid 472 b* mangium (second generation) 334 a mangium 464 b auriculiformis 636 c *Means values followed by different letter within a column are significantly different at 5% level. Mechanical properties Results showed that between species differences for static bending and compression parallel to grain were statistical significant. The comparison of mean results indicate the static bending and compression parallel to grain values for A. magium superbulk were lowest among the acacia studied and its MOR and MOE for static bending are significantly lower than mangium (Table 3). The low density in A. mangium superbulk is responsible for the low strength. The effect of density on strength has long been recognized (Panshin & De Zeeuw 1980, Bowyer et al. 2003). Apparently there were no significant differences in static bending and compression parallel to grain among hybrid, mangium and auriculiformis. The no difference in strength is consistent with similar study (Mohd. Shukari et al. 2002) performed on six-year old mangium and four-year old hybrid. Table 3. Comparison on mean values on some mechanical properties of hybrid mangium (superbulk), mangium and auriculiformis. Species Static Bending MOR (N/mm 2 ) MOE (N/mm 2 ) Compression Parallel to Grain Young s MCS (N/mm 2 Modulus ) (N/mm 2 ) hybrid 85 a* 9614 a 62 a 1253 a magium superbulk 55 b 8185 b 50 b 901 a mangium 78 a 9992 a 53 ab 1076 a auriculiformis 89 a 8214 ab 59 ab 1094 a *Means values followed by different letter within a column are significantly different at 5% level. Fibre morphology Total main-stem fibre length averaged mm in hybrid which was significantly longer than auriculiformis and mangium (Table 3). Literature on anatomical properties of mangium x auriculiformis hybrid was hardly available. This may due to fact that hybrid is still new. The only literature on hybrid was by Haifah (2002) who reported the overall average anatomical properties found in Sabah. The average fibre length of hybrid planted in Sabah was mm (Haifah 2002) which was 5

6 longer than the average value found in this study. This study did not show significant difference in fibre length between auriculiformis and mangium. Table 3 showed that hybrid recorded the smallest average fibre diameter (17.16 µm) and fibre lumen diameter (12.75 µm), however average fibre wall thickness (2.21 µm) was significantly thicker than auriculiformis and mangium. Previous study by Haifah (2002) showed thicker average fibre wall thickness and fibre diameter in hybrid from Sabah averaged at 3.69 µm and µm, respectively. Table 3. Fibre characteristics of mangium, mangium superbulk, and hybrid Anatomical properties hybrid mangium superbulk mangium auriculiformis Fibre length (mm) 0.96 b 0.91 a 0.93 ab 0.89 a Fibre Wall thickness(µm) 2.21 c 1.88 a 2.03 b 2.00 b Fibre diameter (µm) a d b c Fibre lumen diameter (µm) a c b b Runkel ratio 0.35 c 0.22 a 0.31 b 0.29 b Length to thickness ratio 434 b 484 c 404 a 444 b *Means values followed by different letter within a column are significantly different at 5% level. Natural durability The average weight losses of the wood blocks after a ten weeks exposure to fungi were shown in Table 4. The wood blocks that were exposed to the three test fungi exhibited different susceptibility to fungi attack. Significant differences of the average weight loss were observed between species (Table 4). Severity of decay by Trametes versicolor, Schizophyllum commune and Rigidoporus microporus were significantly different. This showed that the amount of wood decayed by the three test fungi on mangium, auriculiformis, superbulk, hybrid and Hevea brasiliensis (Rubberwood) were not the same. Hevea brasiliensis recorded the highest weight loss among all the wood species for all fungi in this study. Among species, mangium and hybrid recorded the highest weight loss due to Trametes versicolor. Rigidoporus microporus apparently decay auriculiformis the most. All species seem to be less susceptible to Schizophyllum commune. 6

7 Table 4. Mean weight loss of A. mangium, A. auriculiformis, A.mangium superbulk, hybrid and H. brasiliensis after ten weeks exposure to Trametes versicolor, Schizophyllum commune and Rigidoporus microporus Wood species Mean weight loss (%) T. versicolor S. commune R. microporus mangium 11.19* a a a3 auriculifo-rmis 7.21 a a b1 mangium (superbulk) 7.60 a a a3 hybrid a a a2 Hevea brasiliensis b b c3 *Means within a column followed by the same letter are not significantly different at 5% level. Means between column followed by same number are not significantly different at 5% level. Visual ratings of test samples for termite resistance test were based on American Wood- Preservers Association Standard E1-97. In this standard, visual rating consist of number from 0 to 10, which indicate 0 as failure due to attack and 10 as sound, or surface nibbles permitted. The average visual rating of test samples is represented in Table 5. Hevea brasiliensis recorded the lowest average scores at 2.2, while superbulk recorded an average score of 3. mangium and auriculiformis were rated at 3.2. hybrid score was averaged at 3.1. Attack of termites on Hevea brasiliensis and superbulk are categorized as heavy damage. Based on this rating, acacia hybrid was classified as moderately resistant and the rest of the samples were classified as non-resistant to termites attack. Table 5. Visual ratings of A. mangium, A. auriculiformis, A. mangium superbulk, hybrid and H. brasiliensis exposed to 150 workers and 50 soldiers of Coptotermes sp. for three weeks in a no-choice laboratory test Tree species Visual Rating Classification mangium 3.7 Non-resistant auriculiformis 3.7 Non-resistant superbulk 3 Non-resistant hybrid 6.1 Moderately resistant Hevea brasiliensis 2.2 Non-resistant Conclusion The average annual rate of planting for the establishment of commercial plantation forests in Sarawak has been well below the required rate to achieve the one-million-ha target by the year Thus concerted effort must be made by the LPF Holders and the state Government must remained committed to realise the target. This study indicated that marked differences 7

8 in wood properties and qualities between hybrid and second-generation mangium. The lower density and strength of second generation mangium does not necessarily mean it s of lower quality. Further study is required to accurately assess the wood properties of both acacias because of variation effects due to locations, growth characteristics and silvicultural practices. References ASTM Standard Method of Accelerated Laboratory Test of Natural Decay Resistance of Woods, ASTM Standard D Book of ASTM Standards Vol 04.10, Section 4. West Conshohocken, PA. Berlyn, G.P. & Miksche, J.P Botanical Microtechnique & Cytochemistry Ames, Iowa. The Iowa State University Press. United State of America. British Standard 373:1957. Method of Testing small Clear Specimens of Timber. BS 373:1957. Watelow & Sons Limited, Westminister, London. 32p. Haifah, Y Anatomical and fibre properties of Hybrid grown in Sabah. Unpublished Project Paper, UPM Serdang. Hashim, M.N., Maziah, Z. and Sheikh, A.A The incidence of heartrot in mangium Willd. plantations: a preliminary observation. In: Appanah, S., Ng, F.S.P. and Roslan, I. (eds.). Malayan Forestry and Forest Products Research. Proceedings of the Conference. Forestry Research Institute Malaysia, Kepong. pp Japan Wood Preserving Association (JWPA) standard 11(1) Methods for Testing Effectiveness of Surface Treatment (Brushing, Spraying and Dipping) with Termiticides Against Termites (1) Laboratory Test. Weinland, G. and Zuhaidi, A Management of mangium stands: Tending issues. In: Appanah, S., Ng, F.S.P. and Roslan, I. (eds.). Malayan Forestry and Forest Products Research. Proceedings of the Conference. Forestry Research Institute Malaysia, Kepong. pp Mohd. Shukari Midon, Ab. Rasip Ab. Ghani and Mohd. Lokmal Ngah Comparative Strength Properties of Six-Year-Old Mangium and Four-Year-Old Hybrid. Journal of Tropical Forest Product 8(1): Panshin, A.J. & De Zeeuw, C Textbook of Wood Technology. Fourth edition. McGraw-Hill, New York. 722pp. PERKASA (2009). Seminar on Viability Assessment of Indigenous Tree Species and Propagation Techniques for Planted Forest Development in Sarawak. PERKASA, Vol. 5/6 (May-June). pp