Environmental factors and wood qualities of African blackwood, Dalbergia melanoxylon, in Tanzanian Miombo natural forest

Abstract

African blackwood (ABW) (Dalbergia melanoxylon) mainly occurs in the coastal areas of East Africa, including in Tanzania and Mozambique, and its heartwood is commonly known to be one of the most valuable materials used in the production of musical instruments. Although the heartwood is one of the most expensive timbers in the world, very low material yield has recently resulted in the significant reduction of natural individuals. This might have serious impact on local communities, because this tree is apparently the only species that can support their livelihood. Therefore, a solution to the problem is urgently needed in terms of the sustainable development of communities. In this study, we survey environmental factors (stand structure and soil properties) in the Miombo woodlands of southern Tanzania, where ABW was once widely distributed, to clarify the factors affecting growing conditions of ABW. Three community forests located in Kilwa District, Lindi, Tanzania, were selected as the survey sites, and 10-13 small plots (0.16 ha/plot) were randomly established at each site. In addition, the stem qualities of standing trees were evaluated by visual inspection rating and a non-destructive measurement of stress-wave velocity, for understanding the relationship between environmental factors and growth form. It was found that ABW was widely distributed under various environmental conditions with intensive population, and that their growth form depended on environmental factors. Since there was no significant difference of stress-wave velocities among the site, our findings suggest that the dynamic properties of ABW trees does not depend on growth conditions, which is generally influenced by various external factors. These results present important information regarding the sustainable forest management of ABW.

Selection of dipterocarp species for enrichment planting in a secondary tropical rainforest

“…where T m (ms/m) is the transmission time per length basis (ls/m), T reading is the average stress wave reading (ls; 6 replications per tree), and LD is the length of the distance between the first and second stop probes (m). SWV (km/s) was calculated using the following equation (Wang et al 2000(Wang et al , 2004Nakai et al 2019):…”

African blackwood (Dalbergia melanoxylon) and other local Tanzanian tree species’ biological performance against subterranean termites and wood decay fungi

“…The general characteristics of the ABW tree have previously been reported as follows: an average height of 5 m to 7 m; multi-stemmed; and has an irregularly shaped crown (Lovett 1987;Sacandé et al 2007). In Tanzania, ABW is naturally distributed with population densities of 9 trees/ha to 90 trees/ha and is often grown in clusters (Gregory et al 1999;Opulukwa et al 2002;Mariki and Wills 2014;Nakai et al 2019). Some local community forests in the Kilwa District (Lindi, Tanzania) are designated FSC (Forest Stewardship Council) certified forests supported by the local NGO (Non-Government Organization): the MCDI (Mpingo Conservation & Development Initiative).…”

Flow deformation characteristics of African blackwood, Dalbergia melanoxylon

“…In Tanzania, ABW trees tend to be observed in a semi-deciduous formation including deciduous and evergreen trees, i.e., the miombo woodlands, which are characterized by an abundance of three genera: Brachystegia, Julbernardia and Isoberlinia [1,2]. The trees naturally grow in clusters, with a population density that has been estimated as 9-90 trees/ ha [3][4][5][6].…”

“…We recently reported that the growth characteristics of ABW are affected by the surrounding environment, i.e., topography, climate and human activities. Nevertheless, the tree can survive under various environmental conditions with intensive population [6]. Several defects that frequently occur in natural trees, such as lateral twists, deep fluting, and knots including cracks, can affect the operation of sawmills [10].…”