Khaya ivorensis, popularly known as African Mahogany, is a valuable and well-known tropical timber in the international market [1]. It has many uses including the use for high-quality furniture, interior finishing, ship construction, cabinet making, etc. It has unique processing and working properties. Due to its high quality, there is a huge demand for it, resulting in the overexploitation of the species in Ghana. The over-dependence on a few prime species including Khaya ivorensis as well illegal logging has been a major contributing factor to the dwindling timber resource in Ghana. This has led to the depletion of Khaya ivorensis in the southwestern forest zone of Ghana [2]. To curb the overexploitation and depletion of the resource, sustainable forest management has become a priority for the government and researchers, as well as the promotion of the use of lesser-used / lesser-known species and plantation-grown species. Khaya ivorensis plantations have therefore been established to ensure the continuous supply of the species.
However, most plantation-grown species have been reported to have inferior wood quality than the naturally grown ones [3]. The utilization of plantation species is faced with many challenges since information on the history of their use is not available [4]. Fast-growing timber species are also known to have altered properties and tend to be inferior to the naturally grown ones. Khaya ivorensis is reported to be a fast-growing species and thrives well in evergreen and semi-deciduous forests [5].
Planted Khaya ivorensis in Ghana suffer from a shoot-borer attack which results in severe mortality at younger ages. Interventions from research have helped introduce more tolerant genotypes of Khaya ivorensis that are fast-growing and self-pruning, that survive the shoot-borer attack [6]. This has encouraged the establishment of more plantations in Ghana. According to [7], fast-growing plantation species can reach harvestable sizes quicker than trees from the natural forest and may have higher proportions of juvenile wood than matured wood. This has an effect on the wood quality of fast-growing species and has hindered their use as timber for construction purposes [7]. The use of fast-growing species has been limited to pulp & paper, fuelwood for energy, which are not so profitable for foresters [8].
To address the concerns on the utilization potential of fast-growing Khaya ivorensis that had survived the shoot borer attack, their properties need to be established. Zbonak et al. [9] investigated the physical and sawing properties of plantation-grown Khaya senegalensis trees from Australia. Studies have also been conducted on the physical & mechanical [10], chemical and durability properties [11] of plantation-grown Khaya ivorensis from Ghana. However, one property that has not yet been studied is the thermal behaviour or capacity of the plantation-grown species. Thermogravimetric analysis was conducted in this study to assess the thermal behaviour of the species.
Thermogravimetric Analysis (TGA) is a technique in which the mass of a substance, upon heating, is monitored as a function of temperature or time. The sample specimen is subjected to a controlled temperature program in a controlled atmosphere [12]. The mass of the specimen could increase or decrease upon heating. It is also a measure of a sample’s weight as it is heated or cooled in a furnace. In the micro-particle scale, thermogravimetric analysis (TGA) is one of the techniques used to determine the thermal properties of wood [13].
The objective of the study was to analyze the thermogravimetric properties of plantation-grown Khaya ivorensis and compare them with those of natural stands to promote its use.