Abstract:
Preferred timber species are increasingly becoming unavailable due to overexploitation of natural
forests. There is a growing shift in demand to Lesser-Used Species (LUS), like Artocarpus altilis
as substitutes in Nigeria. Knowledge on wood quality and durability of LUS would enhance
efficient utilisation. However, there is limited information on wood properties and natural
durability of Artocarpus altilis. Therefore, physico-mechanical, anatomical and chemical
properties, as well as, natural durability of Artocarpus altilis were investigated.
Four trees of Artocarpus altilis were purposively selected and felled based on maturity (45.0±0.5
years) at Gambari Forest Reserve, Oyo State, Nigeria. Billets (500 cm) were obtained from base,
middle and top of merchantable height of each tree. Each billet was partitioned into corewood,
innerwood and outerwood and processed into various dimensions using standard procedures.
Physical (density, kg/m
3
; shrinkage, %) and mechanical (impact bending, J/m2
; Modulus of
Rupture- MOR, N/mm2
; Modulus of Elasticity-MOE, N/mm2
; shear strength, N/mm
2
; Maximum
Compressive Strength parallel to grain MCS//, N/mm2
) properties were determined using
standard methods. Cell morphology (Runkel Ratio, vessel diameter, µm) and chemical properties
(cellulose, %; hemicelluloses, %; and ash content, %) were determined following standard
procedures. In a factorial arrangement, graveyard experiment and Accelerated Biological Test
(ABT) following White Rot (WR) and Brown Rot (BR) fungi biodegradation were used to assess
weight loss for 48 and 20 weeks, respectively. Data were analysed using descriptive statistics,
Pearson Product Moment Correlation and ANOVA at α0.05.
Density decreased significantly from base (602.7±64.5) to top (570.7±56.0) and from outerwood
(629.3±54.3) to corewood (590.4±59.4). Shrinkage ranged from 4.9±0.8 (base) to 6.2±0.5 (top)
and increased from corewood (5.1±0.8) to outerwood (6.4±0.7). Impact bending increased from
base (14.3±3.9) to top (16.5±4.0) and varied from 14.5±3.1 (corewood) to 17.6±4.4 (outerwood).
The MOR and MOE were highest at base (42.1±8.8, 3993±1983) and least at top (32.9±5.4,
3145±520.4), but decreased from corewood (37.6±1.9, 3630.1±555.5) to outerwood (36.6±7.2,
2986.0±410.6), respectively. Shear strength and MCS// decreased significantly from base (9.7±1.7,
23±4.1) to top (8.5±0.9, 18±2.7) and from corewood (10.8±1.4, 22.5±2.5) to outerwood (8.5±1.1,
18±3.6), respectively. Runkel Ratio was highest at top (0.7±0.2), least at base (0.5±0.2) but
decreased from corewood (0.7±0.2) to outerwood (0.6±0.2). Vessel diameter varied from base
(238.0±64.8) to top (238.6±57.8) and increased from corewood (238.7±53.5) to outerwood
(249.0±61.8). Cellulose, hemicellulose and ash content were highest at base (47.8±0.7, 27.8±1.2,
0.93±0.4) and least at middle (47.1±0.4, 27.1±0.7, 0.92±0.4), respectively. Weight loss decreased
from base (26.5±10.1) to top (24.6±8.6) and increased from outerwood (24.6±5.4) to corewood
(27.8±2.4) in graveyard experiment. In ABT, weight loss varied from base (WR: 4.4±2.1, BR:
5.3±2.5) to top (WR: 4.8±1.7, BR: 5.5±2.9). White rot caused the highest weight loss at corewood
(4.8±2.9) and least at outerwood (4.6±2.0), while BR caused least weight loss at corewood
(5.1±2.2) and highest at outerwood (6.0±6.1). The MOR was positively correlated with MOR
(r=0.54) and impact bending (r=0.56).
Artocarpus altilis could be categorised as medium density wood with mechanical properties being
superior at the base and corewood. The chemical properties indicated species suitability for light
construction and papermaking.