Natural Decay Resistance and Aboveground Outdoor Biocidal Wood Protection of Acacia mangium and Other Lesser-Utilized Species

Tan, Wei Khong (2020) Natural Decay Resistance and Aboveground Outdoor Biocidal Wood Protection of Acacia mangium and Other Lesser-Utilized Species. Masters thesis, Universiti Malaysia Sarawak (UNIMAS).

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Abstract

Malaysian rainforest is one of the most biological diverse of wood varieties and it provides economics values and daily usages for citizens. However, due to increasing of demand and limitation of wood resources, exotic wood species such as Acacia mangium was introduced to forest plantation in order to fulfil the demand. Wood species shows different natural durability to wood decaying fungi when exposed to tropical condition. Hence, the objective of this study was to collect and determine the decay ability of collected Basidiomycetes, to determine the aggressiveness of collected Basidiomycetes. Besides that, natural durability of A. mangium and selected wood species to be determined using accelerated laboratory decay methods according to ASTM D2017-05, to provide extend database to users. 26 fungi species were collected from fields and six decay fungi were successfully cultivated. 11 out of 13 tested fungi show positive reaction to ABTS except Gloeophyllum trabeum and Chaetomium globosum. Coriolus versicolor from FRIM was exhibited the highest percent mass loss (20.8%) and followed by Pycnoporus sanguineus from TRTTC (20.3%) and P. sanguineus from CIVIC Centre (18.9%). Natural durability of A. mangium wood was investigated within and between radial position and stem height. From this study, wood density, extractives content and decay resistance exhibited an inverse curvilinear trend from inner heartwood towards sapwood while water permeability exhibited an inverse bell shape trend from inner heartwood towards sapwood. For example, decay resistance of inner heartwood, middle heartwood, outer heartwood and sapwood at 5.2 m height against P. sanguineus decay test showed 40.7%, 28.7%, 14.1% and 44.8%, respectively. Overall, heartwood of A. mangium exhibited the highest extractives content, density and decay resistance and lowest water permeability. In contrast, sapwood exhibited the lowest extractives content, density and decay resistance to wood decaying fungi and highest water permeability. 32 of Sarawak Lesser Known Species (LKT) were tested in this study. For resistance class, mainly tested LKTs were classified as combination of Class I to III. Example of these species was Podocarpus micropedunculatus which classified as Class III for P. sanguineus and G. trabeum decay tests and Class I for C. globosum decay test. 25.0% or 8 out of 32 tested LKTs were classified as Class IV for wood decaying fungi. Examples of these species were Neesia borneensis, Macaranga pearsonii, Terminallia phellocarpa, Neolamarckia cadamba, Myristica maxima, Duabanga moluccana, Canarium apertum and Artocarpus odoratissimus. Natural durability, hardness, water permeability and extractives content were proved affected by wood density. High wood density provides high extractive contents, high hardness value, high compressive stress parallel to grain and low water permeability.

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