Journal of the Korean Wood Science and Technology

The Korean Society of Wood Science & Technology (한국목재공학회)
권호 표지
DOI QR코드

DOI QR Code

Wood Physical and Mechanical Properties of Clonal Teak (Tectona grandis) Stands Under Different Thinning and Pruning Intensity Levels Planted in Java, Indonesia

  • Gama Widya SETA (Faculty of Forestry, Universitas Gadjah Mada) ;
  • Fanny HIDAYATI (Faculty of Forestry, Universitas Gadjah Mada) ;
  • WIDIYATNO WIDIYATNO (Faculty of Forestry, Universitas Gadjah Mada) ;
  • Mohammad NA'IEM (Faculty of Forestry, Universitas Gadjah Mada)
  • Received : 2022.08.02
  • Accepted : 2023.01.11
  • Published : 2023.03.25
Download PDF
⟨ Previous Next ⟩

Abstract

The objective of this study was to reveal the impact of thinning and pruning regimes on the physical and mechanical properties of clonal teak wood planted in Java. In this study, a 15-year-old clonal teak plantation was carried out and the obtained data were evaluated with analysis of variance (ANOVA). The results showed that different thinning intensities had a significant impact on the alteration of heartwood volume development (F = 25.63; p < 0.0001). Meanwhile, the impact of different thinning treatments in several physical properties depends on the pruning treatment levels [moisture content (F= 12.18, p < 0.0001); tangential shrinkage (F = 15.60, p < 0.0001); T/R ratio (F = 7.17, p < 0.0001); and volumetric shrinkage (F = 10.81, p < 0.0001)]. However, different thinning intensities had no significant impact on wood basic density alteration (F = 0.72, p = 0.486), while pruning intensities affect the differences between radial (F = 3.52, p = 0.030) and volumetric shrinkage (F = 3.13, p = 0.044). In mechanical properties, thinning intensity levels did not promote any significant differences [modulus of elasticity (F = 1.41, p = 0.248); modulus of rupture (F = 0.94, p = 0.392); compressive strength parallel to grain (F = 0.21, p = 0.813); and compressive strength perpendicular to the grain (F = 0.41, p = 0.669)]. Meanwhile, different pruning treatments and combination treatments were not significantly altered all mechanical properties. These results indicated that the thinning and pruning regimes can enhance the mechanical properties without having a serious alteration in the physical properties of clonal teak wood.

Keywords

Acknowledgement

This research is supported by the Ministry of Research and Technology/National Agency for Research and Innovation, The Republic of Indonesia (Letter of Assignment of Work Implementation Number: 2961/UNI.DITLIT/DIT-LIT/LT/2019). The authors thank Wanagama Teaching Forest officials for providing the materials. The authors also express sincere thanks to Nesty Pratiwi Romadini, Ajian Yoga Pratopo, Andi Nugroho, Dede Rosadi, Dhimas Khairuman Brilianto, Deanova Frestiana Br. Pelawi, Gelar Abdi Danayomi, Mr. Sukar, Mr. Nardi, Mr. Mian, Mr. Fajar Setiaji, and Mr. M. Sugiarto for their valuable help during the fieldwork and sample making. This research is part of Gama Widya Seta's Ph.D. dissertation.

References

  1. Aiso-Sanada, H., Ishiguri, F., Diloksumpun, S., Nezu, I., Tanabe, J., Ohshima, J., Yokota, S. 2019. Effects of thinning on anatomical characteristics and wood properties of 12-year-old Eucalyptus camaldulensis trees planted in Thailand. Tropics 28(3): 67-73. https://doi.org/10.3759/tropics.MS19-04
  2. Amoah, M., Inyong, S. 2019. Comparison of some physical, mechanical and anatomical properties of smallholder plantation teak (Tectona grandis Linn. f.) from dry and wet localities of Ghana. Journal of the Indian Academy of Wood Science 16(2): 125-138. https://doi.org/10.1007/s13196-019-00248-7
  3. Basri, E., Yuniarti, K., Wahyudi, I., Saefudin, Damayanti, R. 2015. Effects of girdling on wood properties and drying characteristics of Acacia mangium. Journal of Tropical Forest Science 27(4): 498-505.
  4. Bhat, K.M., Priya, P.B. 2004. Influence of provenance variation on wood properties of teak from the Western Ghat region in India. IAWA Journal 25(3): 273-282. https://doi.org/10.1163/22941932-90000365
  5. Breda, N., Granier, A., Aussenac, G. 1995. Effects of thinning on soil and tree water relations, transpiration and growth in an oak forest (Quercus petraea(Matt.) Liebl.). Tree Physiology 15(5): 295-306. https://doi.org/10.1093/treephys/15.5.295
  6. British Standards Institution. 1957. Methods of Testing Small Clear Specimens of Timber. BS 373:1957. British Standards Institution, London, UK.
  7. Budiadi, Widiyatno, Ishii, H. 2017. Response of clonal teak plantation to thinning and pruning in Java, Indonesia. Journal of Tropical Forest Science 29(1): 44-53.
  8. Cassens, D.L. 1980. Drying Small Quantities of Hard- wood Lumber: Understanding the Effects of Moisture on Wood. Purdue University, West Lafayette, IN, USA.
  9. Christoforo, A.L., de Almeida, T.H., de Almeida, D.H., dos Santos, J.C., Panzera, T.H., Lahr, F.A.R. 2016. Shrinkage for some wood species estimated by density. International Journal of Materials Engineering 6(2): 23-27. https://doi.org/10.5923/j.ijme.20160602.01
  10. Clutter, J.L., Fortson, J.C., Pienaar, L.V., Brister, G.H., Bailey, R.L. 1983. Timber Management: A Quantitative Approach. John Wiley & Sons, New York, NY, USA. p. 333.
  11. Common Fund for Commodity [CFC], International Tropical Timber Organization [ITTO]. 2009. Study on Utilization of Plantation Teak Pre-Project CFC/ITTO 73 FT PPD 68/03 Rev.2 (I). Ministry of Forestry Forest Department Myanmar, Naypyidaw, Myanmar.
  12. Djati, I.D., Tauchi, T., Kubo, M., Terauchi, F. 2015. Mechanical properties and characteristics of young teak for making products. Bulletin of Japanese Society for Science of Design 62(3): 25-34.
  13. Fagerstedt, K.V., Saranpaa, P., Tapanila, T., Immanen, J., Serra, J.A.A., Nieminen, K. 2015. Determining the composition of lignins in different tissues of silver birch. Plants 4(2): 183-195. https://doi.org/10.3390/plants4020183
  14. Filho, A.C.F., Mola-Yudego, B., Gonzalez-Olabarria, J.R., Scolforo, J.R.S. 2018. Thinning regimes and initial spacing for eucalyptus plantations in Brazil. Annals of the Brazilian Academy of Sciences 90(1): 255-265. https://doi.org/10.1590/0001-3765201720150453
  15. Food and Agriculture Organization of the United Nations [FAO]. 2009. The Future of Teak and the High-Grade Tropical Hardwood Sector: Solving the Tropical Hardwood Crisis with Emphasis on Teak (Tectona grandis Linn f.). FAO, Rome, Italy.
  16. Food and Agriculture Organization of the United Nations [FAO]. 2015. Global Teak Trade in the Aftermath of Myanmar's Log Export Ban. FAO, Rome, Italy.
  17. Forrester, D.I. 2015. Transpiration and water-use efficiency in mixed-species forests versus monocultures: Effects of tree size, stand density and season. Tree Physiology 35(3): 289-304. https://doi.org/10.1093/treephys/tpv011
  18. Forrester, D.I., Collopy, J.J., Beadle, C.L., Warren, C.R., Baker, T.G. 2012. Effect of thinning, pruning and nitrogen fertiliser application on transpiration, photosynthesis and water-use efficiency in a young Eucalyptus nitens plantation. Forest Ecology and Management 266: 286-300. https://doi.org/10.1016/j.foreco.2011.11.019
  19. Galih, N.M., Yang, S.M., Yu, S.M., Kang, S.G. 2020. Study on the mechanical properties of tropical hybrid cross laminated timber using bamboo laminated board as core layer. Journal of the Korean Wood Science and Technology 48(2): 245-252. https://doi.org/10.5658/WOOD.2020.48.2.245
  20. Gartner, B.L., Robbins, J.M., Newton, M. 2005. Effects of pruning on wood density and tracheid length in young Douglas-Fir. Wood and Fiber Science 37(2): 304-313.
  21. Hegazy, S.S., Aref, I.M., Iqbal, M. 2014. Effect of thinning regime on wood quality of Acacia salicina trees growing in Saudi Arabia. Wood Research 59(1): 109-122.
  22. Hidayati, F., Fajrin, I.T., Ridho, M.R., Nugroho, W.D., Marsoem, S.N., Na'iem, M. 2016. Physical and mechanical properties of "Mega" superior teak wood and conventional teak planted in educational forest, Wanagama, Gunungkidul. Jurnal Ilmu Kehutanan 10(2): 98-107. https://doi.org/10.22146/jik.16510
  23. Hidayati, F., Sulistyo, J., Lukmandaru, G., Listyanto, T., Praptoyo, H., Pujiarti, R. 2015. Physical and mechanical properties of 10-year old superior and conventional teak planted in Randublatung Central Java Indonesia. Jurnal Ilmu dan Teknologi Kayu Tropis 13(1): 11-21.
  24. Hong, N.E., Won, K.R., Jung, S.Y., Lee, K.S., Byeon, H.S. 2015. Wood properties of Quercus acuta due to thinning intensity. Journal of the Korean Wood Science and Technology 43(6): 721-729. https://doi.org/10.5658/WOOD.2015.43.6.721
  25. Huh, J.S., Kim, J.W., Yoon, J.H., Lee, S.Y. 2020. Analysis of sap production and composition of Acer okamotoanum from artificial stands in different tapping time in Jin-ju region in Korea. Journal of the Korean Wood Science and Technology 48(2): 206-216. https://doi.org/10.5658/WOOD.2020.48.2.206
  26. Iswanto, A.H., Hakim, A.R., Azhar, I., Wirjosentono, B., Prabuningrum, D.S. 2020. The physical, mechanical, and sound absorption properties of sandwich particleboard (SPb). Journal of the Korean Wood Science and Technology 48(1): 32-40. https://doi.org/10.5658/WOOD.2020.48.1.32
  27. Iswanto, A.H., Tarigan, F.O., Susilowati, A., Darwis, A., Fatriasari, W. 2021. Wood chemical compositions of Raru species originating from central Tapanuli, North Sumatra, Indonesia: Effect of differences in wood species and log positions. Journal of the Korean Wood Science and Technology 49(5): 416-429. https://doi.org/10.5658/WOOD.2021.49.5.416
  28. Kadambi, K. 1972. Forestry Bulletin No. 24: Silviculture and management of teak. https://scholarworks.sfasu.edu/cgi/viewcontent.cgi?article=1022&context=forestrybulletins
  29. Kanninen, M., Perez, D., Montero, M., Viquez, E. 2004. Intensity and timing of the first thinning of Tectona grandis plantation in Costa Rica: Results of thinning trial. Forest Ecology and Management 203(1-3): 89-99. https://doi.org/10.1016/j.foreco.2004.07.054
  30. Kim, J.Y., Kim, S.C., Kim, B.R. 2020a. Microfibril angle characteristics of Korean pine trees from depending on provinces. Journal of the Korean Wood Science and Technology 48(4): 569-576. https://doi.org/10.5658/WOOD.2020.48.4.569
  31. Kim, M., Lee, W.K., Kim, Y.S., Lim, C.H., Song, C., Park, T., Son, Y., Son, Y.M. 2016. Impact of thinning intensity on the diameter and height growth of Larix kaempferi stands in central Korea. Forest Science and Technology 12(2): 77-87. https://doi.org/10.1080/21580103.2015.1075435
  32. Kim, M.J., Kim, J.Y., Kim, B.R. 2020b. Mechanical characteristics of Korean red pines according to provinces (Goseong, Hongcheon and Bonghwa-gun). Journal of the Korean Wood Science and Technology 48(5): 666-675. https://doi.org/10.5658/WOOD.2020.48.5.666
  33. Kollert, W., Kleine, M. 2017. The Global Teak Study. Analysis, Evaluation and Future Potential of Teak Resources. International Union of Forest Research Organizations (IUFRO), Vienna, Austria. p. 108.
  34. Koskela, J., Vinceti, B., Dvorak, W., Bush, D., Dawson, I.K., Loo, J., Kjaer, E.D., Navarro, C., Padolina, C., Bordacs, S., Jamnadass, R., Graudal, L., Ramamonjisoa, L. 2014. Utilization and transfer of forest genetic resources: A global review. Forest Ecology and Management 333: 22-34. https://doi.org/10.1016/j.foreco.2014.07.017
  35. Kyaw, T.Y., Germain, R.H., Stehman, S.V., Quackenbush, L.J. 2020. Quantifying forest loss and forest degradation in Myanmar's "home of teak". Canadian Journal of Forest Research 50(2): 89-101. https://doi.org/10.1139/cjfr-2018-0508
  36. Laurila, J., Lauhanen, R., Hakonen, T. 2014. The effect of girdling on the moisture content of small-sized trees. Scandinavian Journal of Forest Research 29(3): 259-265. https://doi.org/10.1080/02827581.2014.896937
  37. Lautenschlager, R.A. 2000. Can intensive silviculture contribute to sustainable forest management in northern ecosystems? The Forestry Chronicle 76(2): 283-295. https://doi.org/10.5558/tfc76283-2
  38. Lukmandaru, G., Manalu, P., Listyanto, T., Irawati, D., Pujiarti, R., Hidayati, F., Rodiana, D. 2016. Chemical properties of 15-year-old teak (Tectona grandis L.f) from different seed sources. Wood Research Journal 7(1): 6-12. https://doi.org/10.51850/wrj.2016.7.1.6-12
  39. Machado, J.S., Louzada, J.L., Santos, A.J.A., Nunes, L., Anjos, O., Rodrigues, J., Simoes, R.M.S., Pereira, H. 2014. Variation of wood density and mechanical properties of blackwood (Acacia melanoxylonR. Br.). Materials & Design 56: 975-980. https://doi.org/10.1016/j.matdes.2013.12.016
  40. Marsoem, S.N., Prasetyo, V.E., Sulistyo, J., Sudaryono, Lukmandaru, G. 2014. Study on the quality of teak wood from a community forest in Gunungkidul: III. Wood physical properties. Jurnal Ilmu Kehutanan 8(2): 75-88. https://doi.org/10.22146/jik.10162
  41. Midgley, S., Somaiya, R.T., Stevens, P.R., Brown, A., Kien, N.D., Laity, R. 2015. Planted Teak: Global Production and Markets, with Reference to Solomon Islands. Australian Centre for International Agricultural Research, Canberra, Australia. p. 92.
  42. Miranda, I., Sousa, V., Pereira, H. 2011. Wood properties of teak (Tectona grandis) from a mature unmanaged stand in East Timor. Journal of Wood Science 57(3): 171-178. https://doi.org/10.1007/s10086-010-1164-8
  43. Mon, M.S., Mizoue, N., Htun, N.Z., Kajisa, T., Yoshida, S. 2012. Factors affecting deforestation and forest degradation in selectively logged production forest: A case study in Myanmar. Forest Ecology and Management 267: 190-198. https://doi.org/10.1016/j.foreco.2011.11.036
  44. Moya Roque, R., Ledezma, V.A. 2003. Effect of plantation spacing on two physical properties of teak wood along the stem. Madera y Bosques 9(2): 15-27. https://doi.org/10.21829/myb.2003.921283
  45. Na'iem, M. 2001. Early Performance of Clonal Test of Teak. In: Potentials and Opportunities in Marketing and Trade of Plantation Teak: Challenge for the New Millennium, Ed. by Hardiyanto, E.B. Gadjah Mada University, Yogyakarta, Indonesia. pp. 271-275.
  46. Na'iem, M. 2014. Forest Productivity Enhancement based on Intensive Silviculture (SILIN): Efficiency Strategy of Forest Area Utilization. In: Darurat Hutan Indonesia, Mewujudkan Arsitektur Baru Kehutanan Indonesia, Ed. by Nugraha, A. Wana Aksara, Banten, Indonesia. pp. 162-183.
  47. Noel, A.R.A. 1970. The girdled tree. The Botanical Review 36(2): 162-195. https://doi.org/10.1007/BF02858959
  48. Nyland, R.D., Kenefic, L.S., Bohn, K.K., Stout, S.L. 2016. Silviculture: Concepts and Applications. Waveland Press, Long Grove, IL, USA.
  49. Pachas, A.N.A., Sakanphet, S., Soukkhy, O., Lao, M., Savathvong, S., Newby, J.C., Souliyasack, B., Keoboualapha, B., Dieters, M.J. 2019. Initial spacing of teak (Tectona grandis) in northern Lao PDR: Impacts on the growth of teak and companion crops. Forest Ecology and Management 435: 77-88. https://doi.org/10.1016/j.foreco.2018.12.031
  50. Pandey, D., Brown, C. 2000. Teak: A global overview. Unasylva 51(201): 3-13.
  51. Perez Cordero, L.D., Kanninen, M. 2003. Heartwood, sapwood and bark content, and wood dry density of young and mature teak (Tectona grandis) trees grown in Costa Rica. Silva Fennica 37(1): 45-54.
  52. Perez, D., Kanninen, M. 2005. Effect of thinning on stem form and wood characteristics of teak (Tectona grandis) in a humid tropical site in Costa Rica. Silva Fennica 39(2): 217-225. https://doi.org/10.14214/sf.385
  53. Pinto, I., Pereira, H., Usenius, A. 2004. Heartwood and sapwood development within maritime pine (Pinus pinaster Ait.) stems. Trees 18(3): 284-294. https://doi.org/10.1007/s00468-003-0305-8
  54. Prabuningrum, D.S., Massijaya, M.Y., Hadi, Y.S., Abdillah, I.B. 2020. Physical-mechanical properties of laminated board made from oil palm trunk (Elaeis guineensis Jacq.) waste with various lamina compositions and densifications. Journal of the Korean Wood Science and Technology 48(2): 196-205. https://doi.org/10.5658/WOOD.2020.48.2.196
  55. Prehaten, D., Hardiwinoto, S., Na'iem, M., Supriyo, H., Widiyatno, W., Rodiana, D. 2021. Productivity of arrowroots and taro grown under superior teak clones with several levels of stand density. Biosaintifika 13(1): 51-57. https://doi.org/10.15294/biosaintifika.v13i1.26428
  56. Quarles, S.L., Valachovic, Y. 2012. Using Wood Quality Measures to Evaluate Second-Growth Redwood. U.S. Department of Agriculture Forest Service, Washington, DC, USA. pp. 553-559.
  57. Rahman, M.M., Fujiwara, S., Hirakawa, Y., Kanagawa, Y. 2004. Wood density in relation to growth rate and tissue proportions of teak grown in Bangladesh. Journal of Forest Planning 10(2): 53-57. https://doi.org/10.20659/jfp.10.2_53
  58. Rahmawati, R.B., Hardiwinoto, S., Widiyatno, Budiadi, Amin, Y., Hasanusi, A. 2021. Space planting, competition, and productivity of a seven-year-old clonal teak plantation in the East Java monsoon forest area. Jurnal Manajemen Hutan Tropika 27(2): 123-131.
  59. Rahmawati, R.B., Widiyatno, W., Hardiwinoto, S., Budiadi, B., Nugroho, W.D., Wibowo, A., Rodiana, D. 2022. Effect of spacing on growth, carbon sequestration, and wood quality of 8-year-old clonal teak plantation for sustainable forest teak management in Java Monsoon Forest, Indonesia. Biodiversitas Journal of Biological Diversity 23(8): 4180-4188. https://doi.org/10.13057/biodiv/d230840
  60. Ramasamy, Y., Galeano, E., Win, T.T. 2021. The Teak Genome. Springer, Cham, Switzerland.
  61. Rao, P.S., Venkaiah, K., Murali, V., Murti, S.S.N., Sattar, S.A. 2001. Evaluation of international teak provenance trial plot in north-east Andhra Pradesh. Indian Forester 127(4): 415-422.
  62. Rini, D.S. 2013. Effect of girdling period time on physical properties of teak (Tectona grandis L.f) from community forest. M.S. Thesis, Universitas Gadjah Mada, Indonesia.
  63. Ross, R.J. 2010. Wood Handbook: Wood as an Engineering Material. Forest Products Laboratory, Madison, WI, USA.
  64. Russo, D., Marziliano, P.A., Macri, G., Proto, A.R., Zimbalatti, G., Lombardi, F. 2019. Does thinning intensity affect wood quality? An analysis of Calabrian pine in Southern Italy using a non-destructive acoustic method. Forests 10(4): 303.
  65. Sargent, R. 2019. Evaluating dimensional stability in solid wood: A review of current practice. Journal of Wood Science 65(1): 36.
  66. Savero, A.M., Wahyudi, I., Rahayu, I.S., Yunianti, A.D., Ishiguri, F. 2020. Investigating the anatomical and physical-mechanical properties of the 8-year-old superior teakwood planted in Muna Island, Indonesia. Journal of the Korean Wood Science and Technology 48(5): 618-630. https://doi.org/10.5658/WOOD.2020.48.5.618
  67. Seo, Y., Pathammavongsa, S., Chhorn, V., Lee, D., Choi, J., Cha, D. 2019. DBH growth for three years after thinning on even-aged Pinus koraiensis and Larix kaempferi plantations in South Korea. Forest Science and Technology 15(1): 1-6. https://doi.org/10.1080/21580103.2018.1530151
  68. Seta, G.W., Widiyatno, Hidayati, F., Na'iem, M. 2021. Impact of thinning and pruning on tree growth, stress wave velocity, and pilodyn penetration response of clonal teak (Tectona grandis) plantation. Forest Science and Technology 17(2): 57-66. https://doi.org/10.1080/21580103.2021.1911865
  69. Shmulsky, R., Jones, P.D. 2011. Forest Products and Wood Science: An Introduction. John Wiley & Sons, Chichester, UK.
  70. Shukla, S.R., Rao, R.V., Shashikala, S., Kumar, P., Sharma, S.K. 2011. Wood quality variation in Tectona grandis (teak) clones from CSO raised at Maredumili (Rajahmundry), Andhra Pradesh. J Indian Acad Wood Sci 8: 116-119. https://doi.org/10.1007/s13196-012-0045-8
  71. Shukla, S.R., Viswanath, S. 2014. Comparative study on growth, wood quality and financial returns of teak (Tectona grandis L.f.) managed under three different agroforestry practices. Agroforestry Systems 88(2): 331-341. https://doi.org/10.1007/s10457-014-9686-5
  72. Siswamartana, S., Rosalina, U., Wibowo, A. 2005. Seperempat Abad Pemuliaan Jati Perum Perhutani. Pusat Pengembangan Sumber Daya Hutan Perum Perhutani, Jakarta, Indonesia.
  73. Smith, D.M. 1986. The Practice of Silviculture. John Wiley & Sons, New York, NY, USA.
  74. Stener, L.G., Rytter, L., Jansson, G. 2017. Effects of pruning on wood properties of planted silver birch in southern Sweden. Silva Fennica 51(2): 1713.
  75. Strugnell, E.J. 1932. The teak forests of Java. Empire Forestry Journal 11(1): 34-41.
  76. Sumardi, I., Alamsyah, E.M., Suhaya, Y., Dungani, R., Sulastiningsih, I.M., Pramestie, S.R. 2022. Development of bamboo zephyr composite and the physical and mechanical properties. Journal of the Korean Wood Science and Technology 50(2): 134-147. https://doi.org/10.5658/WOOD.2022.50.2.134
  77. Thulasidas, P.K., Bhat, K.M. 2012. Mechanical properties and wood structure characteristics of 35-year old home-garden teak from wet and dry localities of Kerala, India in comparison with plantation teak. Journal of the Indian Academy of Wood Science 9(1): 23-32. https://doi.org/10.1007/s13196-012-0062-7
  78. Trockenbrodt, M., Josue, J. 1999. Wood properties and utilisation potential of plantation teak (Tectona grandis) in Malaysia. Journal of Tropical Forest Products 5: 58-70.
  79. Vallejos, J., Moya, R., Serrano, R. 2015. Effects of thinning on diameter, heartwood, density and drying defects of Gmelina arborea. Maderas. Ciencia y Tecnologia 17(2): 365-372.
  80. Viquez, E., Perez, D. 2005. Effect of pruning on tree growth, yield, and wood properties of Tectona grandis plantations in Costa Rica. Silva Fennica 39(3): 381-390. https://doi.org/10.14214/sf.375
  81. Wahyudi, I., Arifien, A.F. 2005. Comparative study on anatomical structure and physical-mechanical properties between tissue cultural- and conventional teakwoods. Jurnal Ilmu dan Teknologi Kayu Tropis 3(2): 9-15.
  82. Wang, S.Y., Lin, C.J., Chiu, C.M. 2005. Evaluation of wood quality of Taiwania trees grown with different thinning and pruning treatments using ultrasonic wave testing. Wood and Fiber Science 37(2): 192-200.
  83. Wanneng, P.X., Ozarska, B., Daian, M.S. 2014. Physical properties of Tectona grandis grown in Laos. Journal of Tropical Forest Science 26(3): 389-396.
  84. Wardani, B.W., Na'iem, M. 2008. Clonal test of teak (Tectona grandis, L.f) evaluation aged 9 years old in KPH Ciamis and KPH Cepu Perum Perhutani. M.S. Thesis, Universitas Gadjah Mada, Indonesia.
  85. Wessels, C.B., Malan, F.S., Rypstra, T. 2011. A review of measurement methods used on standing trees for the prediction of some mechanical properties of timber. European Journal of Forest Research 130(6): 881-893. https://doi.org/10.1007/s10342-011-0484-6
  86. Wu, S., Xu, J., Li, G., Risto, V., Lu, Z., Li, B., Wang, W. 2010. Use of the Pilodyn for assessing wood properties in standing trees of Eucalyptus clones. Journal of Forestry Research 21(1): 68-72. https://doi.org/10.1007/s11676-010-0011-5