Bowen Journal of Agriculture Vol. 3( J). March 1006 

74 

PHYSIOGNOMIC FEATURES OF NEEM AND ITS PROSPECT 
FOR UTILITY AS CONSTRUCTION WOOD 
IN NORTH EASTERN NIGERIA 
*Akpan, M., **Oluftmi, B. and J.A. Akande*** 
*Department of Forestry and Wildlife Management 
Federal University of Technology, Vola, Adamawa State. 
Email: michaelakpn@yahoo.com 
**Department of Forestry and Wood Technology 
Federal University of Technology, Akure, Ondo State 
***Department of Environmental and Resource Technology 
Bowen University, Iwo, Osun State 
ABSTlUcT 
The paper examined the macroscopic features of Neem (Azadirachta indica A. Juss) in relation to its 
utilization for timber. Three study 'Iocations were randomly selected from defined vegetation zones of 
northeastern Nigeria. These are Maiduguri (Sahel savanna) Yola (Sudan savanna) and Bauchi (Guinea 
savanna). Fifteen (15) trees were sampled from each site and the physiognomic features examined 
were (1). Merchantable height (2). Diameter at breast height (D.b.h.) and (3). Bark thickness. Results 
showed a mean merchantable height of 23.73m, diameter of 71.81cm and bark thickness of 1. 17cm. 
TM>-way analysis of variance (ANOVA) sho.ved no significant differences (P.:s.O.05) in the tree species 
height, diameter, and bark thickness between the various vegetation zones and tree samples. The 
physiognomic features of Neern compared well with some local tree species used in timber fabrication. 
Further research is recommended on the species density and strength properties in relation to timber 
utifisation. 
Keywords: Tree height, D.b.h., bark thickness, timber fabrication, Neem, vegetation zone 
INTRODUCTION 
Wood is a renewable and naturally occurring polymeric material. Under 
appropriate conditions, it has adequate structural and dimensional stability. It also has 
high strength and load bearing capacity in relation to its density. Timber could be 
treated to resist insects, wood worms and fungal attacks, as well as provide an 
attractive natural appearance. Fire resistance of wood can also be improved by using 
compatible chemical treatments. Its thermal insulation, acoustic value, seasoning and 
processing have shown wood to be an excellent constructional material (Porter 200 I). 
This is why timber is extensively utilized in all sorts of architectural and building 
constructions. 
In the last ten years, there has been a significant rise in the demand and use of 
timber in northern Nigeria. Considering the long hauling distance for wood species 
currently in the market, timber is gradually becoming scarce and expensive in this, 
area of the country. There is need therefore, to find alternative wood species of 
adaptable local provenance to supplement existing economic species commonly in 	) 

Prospect of utilizing Neem as construction wood 
75- 
use. This research becomes pertinent, as the commercial wood species commonly 
used for constructional purposes in northern Nigeria are very limited. Most of the 
timber for furniture and building constructions come from the rainforest of the south 
(Akpan 200 I a) but the procurement and. transport arrangements are beset. with 
obvious difficulties that must be overcome to tame the escalating price. O~ this note. 
alternative wood species that are autecologically successful in northern Nigeria 
deserve attention. 

Of the prospective wood species. Azadirachtaindica stands prominent, as it is. the 
most widely grown economic tree species in; the northern part' 'of Nigeria (Akpan. 
200 I b). Furthermore, research carried out byRadwanski (1969)"in Sokoto showed 
that Azadirachta indica- is fast growing andean be established without irrigation ill 
the arid regions, It grows well on poor, shallow,' stony or sanely soils,' Its roots have 
unique physiological capacity to extract nutrients from highly leached sandy soils. 

There exists a wide information base on the utilization of Ncem leaves and seeds 
for medicinal purposes (Redknap 1981, Khalid et a/. 1989). Notwithstanding, there is 
apparent information gap as' to its macroscopic properties in relation to timber 
utilization in northern Nigeria. The present effort considered the physiognomic 
properties of Azadirachta indica viz:- tree eight, diameter at breast height (d.b.h.) 
and bark thickness with a view of establishing the biomass value in relation to timber 
utilization. Randomly selected locations representing various vegetation zones in 
northeastern Nigeria (Figure I) were studied. The study locations are Maiduguri 
(Sahel savanna), Y ola (Sudan savanna) and Bauchi (Guinea savanna), 
	
LEGEND 
International boundaries ~)l- 
State boundaries 
Sahel savanna 
Sudan savanna 
Guinea savanna 
Study lecations 
Montane forest 
Figure 1. Vegetation map of northeastern Nigeria showing the study locations 
_ ... - 

• 
.A 

Bowen Journal of Agriculture Vol. 3(1). March 2006 
METHODOLOGY 

76 

Thirty-three (33) matured Neem trees were chosen by selective random sampling 
from free areas using diameter at breast height of at least 60cm as basis in each of the 
three study locations. Out of this number, 15 tree samples were randomly selected for 
the research. In each of the study locations, the species-area curve method as 
described by Greenwood (1999) was used in determining the tree species' inventory 
for their isolation. Allotting an index number to each of the 33 initially chosen tree 
species, 15 tree samples were selected from each of the study locations. Replica 
numbers were placed in a container. The container was vigorously shaken before 
numbers were picked from it. The picked number for a particular tree in each of the 
study locations qualified the tree bearing that number for final selection. Thus. a total 
of 45 tree samples were isolated from the three study locations. 
Tree height determination 
With a spiegel relascope, the heights of the 45 selected trees were determined. 
This was done by choosing a desired scale factor of 20 from the instrument and a 
constant baseline of 10m from the base for each of the 45 tree samples. Afterwards. 
the relascope was focused in such a way that its graduated scale readings were in 
vertical line with the crown of the trees, using the adjuster. Then, the top readings of 
the graduated scale, as well as the bottom readings for the 45 trees were recorded 
accordingly. The tree heights were calculated using the following equation obtained 
from Florescu (1981). 

TH = TR-BR x BD x cose(m) 
	SF 	1 
where 
TH = tree height (m) 
TR = top reading 
BR = bottom reading 
SF = scale factor 
BD = baseline distance (m). 

(1) 

Trunk diameter determination 
In order to determine the diameters of the trees, their circumferences were 
measured at diameter at breast height (d.b.h.), using a flexible tape. Based on 
the mathematical relationship between Circumference (C) and Diameter (D), 
the diameters of the tree samples were calculated using the following 
equation: 

C = Dy(cm) 
Descriptions of the shapes of the trunks were aided by visual sense. 

(2) 

Prospect of utilizing Neem as construction wood 
.0; 	,of 

77 

Barlj thickness determination 
In determining the thickness of the barks of the trees, the increment borer 
was used. The instrument was screwed into the bark of the trees up to the 
sapwood; and the corresponding readings in line with the thickness of the tree 
barks were taken. The possible effects of compression in boring were 
considered negligible. 
Mean and standard deviation (SD) values of each of the above highlighted 
parameters were obtained and Analysis of variance (ANOY A) statistical 
function was utilised to analyse the data by testing the level of significance 
between the sampled trees, as well as between the various vegetation zones. 
The Fisher's least significant difference (LSD) was used to analyse the 
established variation. 
RESULTS AND DISCUSSION 
Tree height 
The heights of the sampled tree species range from 19.2Om to 27.57m in the 
Sahel savanna zone and 19.73m to 27.33m in Sudan savanna while Guinea savanna 
has a range of 19.98m to 28.0Om. The mean values of the sampled tree heights in 
Sahel. Sudan, and Guinea savanna zones are 23.30111, 23.72m. and 24.18m 
respectively. The overall mean of the Neem tree height across the vegetation zones is 
23.73m (Table I). The extrapolated mean height of 23.73m for Neem tree compare 
favourably with some of the tree heights used for timber in Nigeria. Examples are 
Tectono grandis and Diospyros crassiflora, with heights of 20m and 22m 
respectively. Tectono grandis is a notable construction and furniture material. The 
merchantable heights of many other local tree species commonly used for timber are 
in the higher range: 45m for Chlorophora excelsa, 45m for Pericopsis elata, 40m for 
Khaya ivorensis. 30m for Mansonia altissima, 50m for Triplochiton scleroxylon, 40m 
for Aftelia africana, 55m for Lophira alata, 50m for Terminalia superba, 45m for 
Entandrophragma cylindricum, 31m for Eribroma oblonga and 45m for 
Entandrophragma candollei (Ghelmeziu 1981, Akpan 1998). These figures indicate 
that the height of Azadirachta indica could be a reason why the tree has not been 
widely utilized for timber in Nigeria as a whole. However in timber lean regions, 
since an optimal bole length of 3. 60m is recognized (NCP2 1973). it follows that an 
average of six standard lengths can be satisfactorily obtained from a merchantable 
Neem tree. Geometrically, the tree has a cylindrical shape with slight tapering along 
its plane towards the crown. 
Results of the analysis of variance from the different vegetation zones 
showed no significant difference in tree heights at 5% level of probability 
(Table 2). Also, the Least Significant Difference (LSD) analysis confirmed no 
significant difference between Neem heights from the three vegetation zones 
(Table 3) .. 

Table 1. Height, diameter and bark thickness of Azadlrachta indica in three vegetation zones of northeastern Nigeria 			
	Maiduguri(Sahel Savanna) 		Yola (Sudan Savanna) . 		Bauehi (Guinea Savanna) 			Mean Values 		
	Height 	Di.meter 	B.rk 	Height 	Diameter 	B.rk 	Height 	Di.meter 		B.rk 	Height 	Diameter 	Bark 	
Tree 	(m) 	(em) 	Thickn- 	(m) 	(cm) 	'Thickn- 	(m) 	(cm) 		Thickn- 	(m) 	(cm) 	Thickn- 	
samples 			ess(em) 			ess(cm) 				ess(cm) 		.-., . 	ess(cm) 	
1 	26.04 	79.20 	1.38 	19.92 	70.75 	0.83 	25.68 	.. -78.20 		1.37 	23.88' . 	76.05 	1.19 	
2 	21.OQ 	65.88 	0.92 	25.70 	76.44 	1.48 	24.90 	68.25 		1.22 	23.87 	'.' 70.19 	1.21 	
3 	24.11 	69.20 	1.15 	20.45 	65.34 	0.78 	20.90 	71.12 		1.32 	21.82 	-68.55 	1.08 	
4 	19.20 	62.31 	0.69 	23.80 	74.85 	1.44 	26.10 	80.13 		1.64 	23.03 	72.43 	1.26 	
5 	24.15 	73.91 	1.25 	26.36 	79.52 	1.53 	21.14 	64.00 		0.72 . 	23.88 	72.48 	1.17 	
6 	27.57 	80.73 	1.48 	19.73 	62.38 	0.65 	26.15 	76.62 		1.30 	24.48 	73.24 ". 	1.14 	
7 	25.64 	74.72 	1.25 	25.92 	74.38 	1.28 	19.98 	63.44 	, 	0.88 	23.85 	70.85 	1.14 	
8 	25.68 	75.44 	1.33 	24.88 	72.24 	1.30 	2.2.35 	70.56 		1.00 	24.30 	72.52 	~1.21 	
9 	20.73 	63.84 	0.70 	26.85 	n.11 	1.40 	2:3.22 	73.12 		1.20 	23.60 	71.36 	1.10 	
10 	22.50 	67.41 	0.92 	26.54 	77.20 	1.40 	26.40 	77.18 		1.52 	25.15 \ 	73.93 . 	1.28 	
11 	25.20 	70.63 	1.22 	20.50 	66.21 	0.70 	. 28.00 	80.85 		1.60 	24.57:' 	72.56 	1.17 	
12 	20.45 	63.00 	0.91 	23.66 	72.00 	1.34 	25.50 	76.00 		1.52 	23.20 	70.33 	1.26 	
13 	19.70 	62.15 	0.65 	20.15 	64.55 	0.69 	20.14 	65.36 		1:00 	19.20 	64.02 	0.78· 	
14 	24.66 	73.99 	1.15 	23.90 	72.15 	1.15 	26.13 	76.25 		1.41 	24.90 	74,13 	1.24 	
15 	22.90 	68.08 	1.11 	27.33 	n.80 	1.45 	26.22 	76.88 		1.40 	25 . .!I8 	74.25 . 	1.32 	
Mean 	23.30 	70.03 	1.07 	23.72 	72.19 	1.16 	24.18 	73.20 		1:27 	23.73 	.71.81 	1.17 	
. 1:)().. ... ......... ..!2: 45 . 	. .:!:~:~~ ....... 	+0.29 	+?:.6:'I. ..... _:!:4:92 ...... 	+0.32 	... .:!:2.25.:!:6.Q.4 ........... .:!:Q:?9 	+0.81 	'+0.24 	+0.71 	

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Bowen Journal ofAgriculture Vol. 3(1). March 2006 
Table 2. ANOV A of Height 

79 

SI' 

SS 

df 

MS 

F 

P-value 

Trees 79.44608000 14 
Zones 5.88885333 2 
Error 224.7191467 28 
Total 310.0540800. 44 

5.67472000 
2.94442667 
8.0256838 

0.71 ns 
0.31 ns 

0.7493 
0.6962 

ns-not significant (P<0.05) 
Table 3. Fisher's Least Significant Difference (LSD) for Height 

Alpha (a) 
Error degree of freedom _. 
Error mean square 
Critical value oft 
Least significant difference 

0.05 
28 
8.025684 
2.04841 
2.110 m 

Zone 
Guinea 
Sudan 
Sahel 

Sample size (N) 
15 
15 
15 

Mean height (m) 
24.187 a 
23.713 a 
23.302 a 

N.B. Meanswith the same letter are not significantly different. 
Trunk diameter 
The Neem tree diameter at breast height (d.b.h.) ranges from 62.15cm to 80.73cm in 
the Sahel savanna, 62.38cm to 79.52cm in Sudan savanna while a range of 63.44cm to 
80.85cm was recorded in the Guinea savanna. The mean trunk diameter for the Sahel 
savanna is 70.03cm and that of the Sudan savanna is 72.19cm while Guinea savanna 
recorded an average diameter of 73.20cm. The overall mean diameter is 71.81cm (Table 
I) 
The diameter of Azadirachta indica at 71.81cm does not favourably compare with 
diameters of many other economic trees used for timber in Nigeria. Some of the 
commonly used timber species and their corresponding diameters as published by 
Ghelmeziu (1981), Akpan (1998), and Tarziu (1983), include Afzelia africana, with a 
diameter of 100cm; Termtnalta superba (diameter of 140cm); Eribroma oblonga (88cm); 
Mitragyna ciliata (90cm); Gossweilerodendron balsamiferum (l20cm); Khaya ivorensis 
(l60cm); Chlorophora excelsa (l20cm); and Mansonia altissima (80cm). These figures 
showed why Azadirachta indica diameter might not strongly attract merchandize when 
compared to other locally available economic trees in Nigeria. However, in line with the 
principle of opening face as applied to timber fabrication in sawmilling; up to 28 boards 
(p lanks) can be obtained from logs of diameter 60cm (Harpole and Hallock 1994). This 

Bowen Journal of Agriculture Vol. 3(1). March 2006 

80 

(planks) can be obtained from logs of diameter 60em (Harpole and Hallock 1994). This 
number is quite satisfactory in relation to the diameter of Azadirachta indica particularly 
in timber deficit regions of the north. Nonetheless, the diameter of Azadirachta indica 
compares favourably with some other timber species like Uapaca guineensis (70em). 
Diospyros crassiflora (50em), Strombosia pustulata (60cm), Sterculia rhinopetala 
(60cm), Combretodendron macrocarpum (70em), and Distemonanthus benthamianu 
(60cm) which are fairly used (Ghelmeziu 1981). 
The analysis of variance showed no significant difference between the diameters of 
trees in the three vegetation zones at P < 0.05 (Table 4). There was also no significant 
difference in diameter between the sampled trees (Table 4). The LSD analysis 
corroborates these findings (Table 5). 
Table 4. AN OVA of diameter at breast beigbt (d.b.b.) 

SV 	SS 	df 	MS 	F 	P-value 	
Trees 	346. 1334S78 	14 	24.72-38184 	0.66ns 	0.7887 	
Zones 	78.S012844 	2 	39.2S06422 	1.0Sns 	0.3623 	
Error 	1043.593049 	28 	37.271180. 			
Total 	1468.227791 	44 				
ns-not significant (P<O.OS) 
Table 5. Fisher's Least Significant Difference (LSD) for d.b.h. 

Alpha (a) 
Error degree of freedom 
Error mean square 
Critical value of t 
Least significant difference 

O.OS 
28 
37.27118 
2.04841 
4.5664cm 

Zone 
Guinea 
Sudan 
Sahel

Sample size (N) 
IS 
IS 
IS 

Mean D.b.h. (em) 
73.198a 
72.19S a 
70.033 a 

N.B. Means with the same letter are not significantly different 
Bark thickness 
The bark thickness ranges from 0.65em to 1.48em in the Sahel savanna. The average 
bark thickness value in this zone is 1.07em. In the Sudan savanna, the bark thickness 
ranges between 0.65cm to 1.53em with a mean of 1.16em while the Guinea savanna has a 
range of O.72em to 1.64em with a mean of 1.27em. The overall mean of the bark 
thickness is 1.17cm (Table l ). The results showed that the bark thickness of Neem is 

Prospect of utilizing Neem as construction wood 

81 

relatively thin in comparison with other tree species. Examples of trees with higher bark 
thicknesses than Neem are Canarium schweinfurthii (2.0cm), Ceiba pentandra (1.8cm), 
and Oxystigma oxyphyllum (2.0cm) (Tarziu 1983). It was observed that the bark has a 
reddish-brown colour with a strongly furrowed pattern in the longitudinal direction of the 
tree. 
There was no significant difference in bark thickness between the zones at P < 0.05. 
Also, no significant difference was found in bark thickness between the sampled trees at 
the same level of probability (Table 6). Significant differences were alS1' not detected in 
the mean differences found to be less than the LSD value (Table 7). The e findings agree 
with earlier works conducted on tree barks by the United States Department of 
Agriculture, which showed that bark thickness does not vary much in mature tree species. 
basically, ranging from 0.50cm to 3.00cm depending on species. Even though tree barks 
are not major components of tropical timber utilisation, they are marketable non-timber 
forest products that should however be assessed. Incidentally, their thickness affects 
timber volume (Phelps 1998, Lucas 1990) since they are embodied in the trunk diameter 
of trees and the volume of timber increases with thinner barks. 
Table 6. ANOVA of bark thickness 

SV 
Trees 
Zones 
Error 
Total 

SS 
0.67172444 
0.29952444 
2.84754222 
3.81879111 

d(
14 
2 
28 
44 

MS 
0.04798032 
0.14976222 
0.10169794 

F 
0.47"' 
1.47'lS 

P-value 
0.9296 
0.2465 

ns-not significant (P<0.05) 
Table 7. Fisher', Least Significant Difference (LSD) for Bark Thickness 

Alpha (a) 
Error degree of freedom 
Error mean square 
Critical value of t 
Least significant difference 

0.05 
28 
0.101698 
204841 
0.2385cm 

Zone 
Guinea 
Sudan 
Sahel 

Sample size (N) 
15 
15 
J 5 

Mean bark thickness (em) 
1.2733 a 
\.1613 a 
1.0740 a 

N B. Means with the same letter are not significantly different 

Bowen Journal of Agriculture Vol. 3(1). March 2006 
CONCLUSION AND RECOMMENDATIONS 

82 

Azadirachta indica could be suitable for timber production, having satisfied similar 
and favourable physiognomic bole features of known economic trees used for timber 
production. This is owed to the large physical size of the tree species in terms of its 
height and diameter. Also, its considerable thin bark categorically constitutes an 
attractive feature for optimum utilization for timber. However, further studies should be 
carried out on its density and strength properties in relation to timber utilisation. 
Incidentally, its shrinkage characteristics have been established to be suitable for timber 
production and utilisation (Akpan and Olufemi 2005). 	. 
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microscopic characteristics ofthe trunk. Sabondale Journal of Technical Education. (I): 121-123. 
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(Azadirachta indica A. Juss) wood in north eastern zone of Nigeria. Global Journal of 
Engineering Research. (1): 17-22. 
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of the National Conference on Revitalization of Agriculture in the Nigerian Economy, Organised 
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Harpole, G.B. and H. Hallock. 1994. Investment opportunity: best opening face. 
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Phelps, R. 1998. General technical report WO-21. USDA, Forest Service.Washington, 
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Porter, B. 2001. Carpentry and Joinery 3. Butterwroth Heinemann Publications, Oxford, 288 pp. 
Radwanski, S.A. 1969. hnprovement of red acid sands by Neem tree in Sokoto. Journal of 
Applied Ecology. (6): 9-14. 
Redknap, R.S. 1981. The use of crushed Neem berries in the control of some insect 
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Tarziu, D. 1983. Tropical forest. Ceres Publications, Bucharest. 376 pp.