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CONTRIBUTION OF PRIVATE FORESTRY TO FOREST
DEVELOPMENT IN NIGERIA: A CASE STUDY OF EVERGREEN
PLANTER, OGUN STATE
Akinbowale A.S., Adesuyi F.E., Offiah C.J and Fasalejo O.F
Department of Forestry and Wood Technology, Akure, Nigeria. Federal University of
Technology.
P.M.B 704, Ondo State, Akure, Nigeria
ABSTRACT
Private forest refers to trees on private agricultural or forest land used to supplement animal
fodder, fuel wood and other basic resources or simply to provide saleable produce. Data were
collected from Bisrod Furniture Company which is located at Ijari, ijebu-Ogun state. The
company is divided into two sections; The Evergreen tree planter (Plantation section) and the
Furniture section. Interview guides was used to collect information from the company records.
The dominant tree species with plantations of various ages, established by the Evergreen Tree
Planter were selected for measurement of growth characteristics. Four age classes were selected
such that age ranges of the plantations were covered. The Tectona grandis plantation are of two
age-series established in 2005 and 2008, respectively while Mansonia altissima and Nauclea
diderrichii plantations were established in 2005. From each age class, one hectare block was
demarcated and divided into 25 m × 25 m temporary sample plots, from which three (3) plots
were randomly selected. A total of 332 trees were recorded in the sample plots for all the age
series. Number of stem per plot were 88, 78, 84, 82 individuals for Mansonia altissima, Nauclea
diderrichii, Tectona grandis (2005), and Tectona grandis (2008) respectively. Simple linear
model and Logarithm models were generated for volume estimation. Logarithm model gave the
best assessment criteria, and was recommended for further use. The interview guide revealed
that, the company has contributed positively to forest development in Nigeria through
employment opportunities to the people, thus, preventing illegal felling.
Keywords: Private Forestry, Forest Development, Tectona grandis, Mansonia altissima, Nauclea
diderrichii
INTRODUCTION
Nigeria is blessed with large expanse of land area and vegetation. However, these important
resources are not sustainably used or managed. In the past, many people in Nigeria treated the
forest resources as though they were inexhaustible. Today, the story appears to be different as the
average Nigerian now realizes that the forest is highly degraded, however exploitation (both
legally and illegally) of the remaining forests has continued till date. The Nigerian natural
forests, which are the sources of economic trees that produce timber (either for building
construction, furniture, shipbuilding), veneer log, fuel wood or the medicinal plants, etc. have
being over exploited and highly degraded, with some of the species under the threat of becoming
extinct (Ladipo, 2010). Despite this, government investment in the regeneration and management
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of the forest is low and dwindling. Though, the Federal government of Nigeria intended to
establish 1,000,000 ha and 800,000 ha of forest plantations in the high forest and the savannah
zones, respectively by the year 2000, only an estimated 700,000 ha of plantations have been
established in the whole country by 2008 (Sayeret al., 1992; Onyekwelu and Fuwape, 2008).This
has led to the involvement of the private sector in the development and the management of forest
resources in Nigeria. Government tree planting programme operating with limited resources will
not be able to establish trees at the required rate, thereby gradually causing wood shortage in the
country. The only way to quickly set out of this problem is to involve private sector participation
in forestry development in Nigeria.
Private forest refers to trees on private agricultural or forest land used to supplement animal
fodder, fuel wood and other basic resources or simply to provide saleable produce. It may be tree
in small woodlot or trees integrated with agricultural crops as agro forestry (Gwandu, 2001).It
can be integrated into agricultural system to provide forest products and to complement existing
farming enterprise or it can be a stand-alone use of the land. Involvement of private forest
owners in management of forest resources implies the use and management of forest resources
by people who are opportune to own natural or artificial forests. Recognition of the role of forest
management and successful reform of the agriculture sector contributed to the introduction of
private forest. It allows people to participate in forest management through organized
programmes which will educate the populance on importance of growing trees and the benefits
of the forest and its resources, thereby preventing deforestation (Gwandu, 2001).(Adeyoju, 2001)
also stated that the forest service in Nigeria failed to take advantage of the harvest boom period
enjoyed by multinational companies in Nigeria to strike for joint investments in forest plantation
and or regeneration schemes. Today, most of the private sector involvement in plantation
establishment has been limited to individuals and schools.
The Evergreen Tree Planter situated at Ijari, Ijebu-ode is a private forest in Nigeria established to
preserve our natural resources that have been neglected over the years, to promote tree planting,
combat environmental degradation, create job and restore the wealth of Nigeria. Therefore, this
study seeks to assess the level of involvement of private plantation owners in the management
and protection of forest resources in Ogun state, Nigeria.
METHODOLOGY
Study Area
The study was conducted at Ijari, Ijebu-ode, Ogun state, in the tropical rainforest ecosystem of
south-western Nigeria. The area lies between latitude 7.0000ᵒ and longitude 3.5833ᵒ .The
population is about 154,032 (Census, 2006). The area has a warm tropical climate with land area
of 192 km2. It has a geographical landscape that consists of extensive fertile soil suitable for
agriculture. The Mean maximum day-time temperature could be as high as about 32ºC while the
average night-time minimum temperature could drops to about 22ᵒC.The rainy season lasts for 9
months annually, between March and November while the dry seasons usually last for 3 months,
between December and February. Agriculture is the main occupation of the people providing
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income and employment for a large percentage of the population. The evergreen forest
vegetation makes the soil suitable for cultivation of cash crops and food crops.
Methods of Data collection
Data were collected from Bisrod Furniture Company which is located at Ijari, ijebu-Ogun state.
The company is divided into two sections; The Evergreen tree planter (Plantation section) and
the Furniture section. Below is how the data were collected.
Company profile, Activities and Challenges
The data on Evergreen Tree Planter profile was obtained from
(i). The company’s documentations (i.e. records) and
(ii). Through interview guides.
Age and silvicultural history of the plantation was obtained from records. The interview guides
was used to collect information from company records. The interviews targeted top management
staffs that are conversant with the company’s activities, both present and previous.
Measurement of tree growth data
The dominant tree species (with plantations of various ages), established by the Evergreen Tree
Planter were selected for measurement of growth characteristics. Four age classes were selected
such that age ranges of the plantations were covered. From each age class, one hectare block was
demarcated and divided into 25 m x 25 m temporary sample plots, from which three (3) plots
were randomly selected. The following growth variables were enumerated within each selected
sample plot:Diameter at breast height (dbh) of all trees, Diameter at the base, middle and top of
two mean trees, whose dbh are closest to the mean dbh of the plot, Total height of the two mean
trees.
Method of data analysis
The data were obtained from the company records and from the interviews.
Basal Area Estimation: The basal area for each tree was computed using the formula suggested
by (Husch et al., 2003):
4
2DBA
Where: BA = Basal area in m2, D = Diameter at breast height (m), π = Pi (3.142)
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Basal area per hectare for each age series was computed by first pooling and summing the basal
areas of the sample plot from the age series and finding their mean and secondly by multiplying
the mean basal area per plot by 16 (i.e. the number of 25 m x 25 m sample plots in one hectare).
Volume Estimation: The volume of all trees in the sample plots was calculated using the
Newton’s formula:
V=
Where V = Volume (m³), H = Total height (m), Db = Diameter at the base (cm), Dm = Diameter
at the middle (cm), Dt = Diameter at the top (cm) and π = 3.142
Volume per hectare for each age series was computed by first summing the volume of the sample
plots from the age series and finding their mean and secondly by multiplying the mean volume
per plot by 16 (i.e. the number of 25 m x 25 m sample plots in one hectare).
Volume model generation: Volume equations are mathematical expressions which relate tree
volume to tree’s measurable attributes such as diameter at breast and/or height. They are used to
estimate the average content for standing trees of various sizes and species (Avery and Burkhart,
2002). It is estimated as:
V= α + β1D + eij
LnV= α + β1LnD + eij
V= α + β1D2H + eij
Where, V = tree volume, D is the DBH, H = tree height, Ln = natural logarithm, α, and β1 are the
regression parameters, eij is an error term
where, V is the tree volume, D is the DBH (cm), H is the tree height (m), α, β1 and β2 are
regression coefficients to be determined, Ln is the natural logarithm.
Assessment of the models: The models were assessed to test their plausibility and suitability for
further use. The following statistical criteria were used:
Significance of regression (F - ratio): - The tabulated critical value of F at p < 0.05 was
compared with the calculated F-ratio. Where F-calculated exceeds F-tabulated, equations were
considered significant and useful for prediction.
Multiple correlation coefficient (R): R values >0.50 indicated a good fit.
Coefficient of determination (R2): Models were acceptable at R2value >50%.
The regression standard error: The value must be relatively small for a model to be valid.
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Model validation
All the models were validated by comparing predicted volumes with field results with statistical
indices and graphical analyses of residuals (Rupsys and Petrauskas, 2010). All field data were
divided into two sets. The first set is the calibrating set (80%) which comprised growth variables
from 265 trees. These were used for generating the models when all species were pooled. The
second set (validating set) comprised tree data from 67 stems (20%). These were used for
validating the models (Cooper and Weekes 1983). For the species, all data were used for
calibrating and validating (Adekunle et al., 2013). Model outputs were individually compared
with observed values using the Student t-test for paired means (Neter et al., 1996) and the simple
linear regression equation (Amaro et al., 1998). To further assess the accuracy of model
predictions, the biases, percentage biases and the Root Mean Square Error (RMSE) were
calculated for the models (Vanclay 1994; Gadow and Hui, 1998)
RESULTS
Company records and interviews
Table 1 revealed the interview result conducted at the company. The result showed that woods
are exploited from their plantation and some of the trees in the plantation are Tectona grandis,
Mansonia altissima, Nauclea diderrichii, Gmelina arborea etc. The Tectona grandis plantation are
of two age-series established in 2005 and 2008, respectively while Mansonia altissima and
Nauclea diderrichii plantations were established in 2005. Some of the wood species in these
plantations had been harvested. Seeds used to establish these plantations were obtained from
Malaysia and Nigeria. Moreover, some of the silvicultural activities carried out by the company
are clearing, pruning, thinning, chemical treatment etc. Each of these operations is carried out by
their trained staffs that carry out these operations. There are 60 workers in the tree planting
section and about 90 workers in the furniture section. The furniture section is sub-divided into
the following sub-sections: wood construction, upholstery, metal fabrication, spraying,
assembling and loading.
Table 1: The summary table of the interview guide
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Volume estimation
Table 2 showed the statistical summary of data obtained for this study. A total of 332 trees were
recorded in the sample plots for all the age series. Number of stem per plot were 88, 78, 84, 82
individuals for Mansonia altissima, Nauclea diderichii, Tectona grandis (2005), and Tectona
grandis (2008) respectively. Mansonia altissima has the highest number of individuals; this was
followed by Tectona grandis. Mean total height and mean DBH ranged from 5.42 to 8.36 and
10.50 to 18.38, respectively. Basal area per hectare ranged from 0.25 to 0.64 (m-2ha) while
1 When was the Evergreen Tree planter
Established?
1984
2 What are the objectives of establishing the
company?
Production of Furniture
3 What are the various sections of the company? Tree planting and furniture production sections
4 When was the sections established? Furniture section was established in 1958 Tree
Planting section was established in 1984
5 What are the Tree species established in the
company
Nuclea didderichi(2005) ,Mansonia altisima(2005),
Tectona grandis(2005) and Gmelina arborea
(2011)
6 What are the Silvicultural practices carried out in
the Company’s plantation?
Clearing, Prunning, Thinning, Beaten-up Chemical
treatment and so on.
7 Has the Company started harvesting his
Plantation?
Yes
8 Do you consume all harvested trees or sell some
proportion?
The harvest are consumed by the furniture section
9 What are the various sections in the furniture
section?
Wood construction, Upholstery, Metal fabrication,
Spraying, Assembling and Loading.
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volume per hectare ranged from 0.78 to 2.53 (m-3ha). However, all the trees encountered in
sample plots were used to generate models. Table 3 showed the Spearman correlation
coefficients between paired tree growth variables. Generally, there was high and significant
correlation among the variables. Correlation was recorded between the logarithm transformed
values for dbh and volume, while the lowest correlation was between total height and volume.
Selected models for estimation of total volume, and their assessment criteria are presented in
Table 4. For the models involving the pooled data, 265trees were involved in model calibration
while 67 data from the pooled data were used for validation. All selected models had significant
correlation coefficients and coefficients of determination, small standard errors of estimates, and
significant F-values. Exceptional is the Mansonia atissima where the first and last model did not
give a good assessment criteria, although, the logarithm model gave a good assessment criteria.
When species were pooled, the logarithm-transformed model using LnD as the predictor variable
had the highest correlation coefficient of 0.91 and R2 of 83%.
The models used showed accurate estimates of timber volume. Table 5 showed validation result.
The best model estimates were compared with student T-test. The result showed that there were
no significant differences between the observed and predicted volume for all the models
validated. The result also showed small percentage biases and RMSE value, which confirmed
the goodness of fit of the model. Fig. 1 showed the graphic presentation of residual plots against
predicted volume (total volume for pooled and individual species). All the models have the
regression line passing in between the middle of the data indicating that, there was no upward or
downward bias. Also, there were no multicollinearity problems with these models since only a
single predictor variable was involved in their simulation.
Table 2. Summary of tree growth variables.
Species MDbh(cm) MHt (m) Ba/ha (m2/ha) V/ha (m3/ha)
No of
stem
Mansonia altissima
(2005) 17.66 8.36 0.55 2.26 88.00
Nauclea diderrichii
(2005) 10.50 7.53 0.24 1.11 78.00
Tectona grandis (2005) 18.38 8.35 0.64 2.53 84.00
Tectona grandis (2008) 10.73 5.42 0.25 0.78 82.00
Total 57.28 7.44 1.68 6.68 332.00
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Table 3 Spearman correlation matrix for tree growth variables in ever green planter.
DBH(cm) Ln Dbh
Total height
(m) BA(m2)
volume
(m3) Ln volume
DBH(cm) 1
Ln Dbh 0.97 1
Total height 0.68 0.69 1
BA 0.98 0.91 0.64 1
Total volume (m3) 0.64 0.60 0.54 0.64 1
Ln volume 0.89 0.93 0.79 0.82 0.76 1
Table 4. Models generated for total stand volume estimation and their assessment criteria for
pooled and species in Evergreen planter.
Models R R2 SE F-ratio*
Ma V=0.01+0.67D 0.28 0.08 0.14 7.75
LnV= 0.89+1.88LnD 0.85 0.72 0.44 216.46
V= 0.03+0.06D2H 0.29 0.08 0.14 8.06
Nd V= -0.06+1.01D 0.85 0.72 0.02 193.24
LnV= 2.03+2.42LnD 0.88 0.77 0.42 259.19
V= -0.03+0.01D2H 0.94 0.88 0.01 599.73
Tg (2005) V= -0.01+1.18D 0.88 0.77 0.04 272.78
LnV= 1.42+2.21LnD 0.95 0.9 0.24 731.07
V= -0.04+0.18D2H 0.94 0.89 0.02 677.65
Tg (2008) V=-0.04+0.67D 0.95 0.9 0.01 758.57
LnV= 1.09+2.10LnD 0.98 0.95 0.19 1911.45
V= -0.02+0.10D2H 0.95 0.91 0.01 854.51
All V= -0.06+0.97D 0.60 0.36 0.08 144.94
LnV= 1.24+2.08LnD 0.91 0.83 0.38 1261.83
V= -0.02+0.09D2H 0.62 0.38 0.08 161.45
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D = Diameter at breast height (cm), H = Total height, Ln = Natural logarithm
Ma- Mansonia altissima, Nd – Nauclea diderrichii, and Tectona grandis
* F-ratios were significant for all the models (p<0.05)
Table 5. Validation results of models for predicting the total volume in evergreen planter with
Student’s t-test.
Mean
observed
value
Mean
predicted
value df t-stat
t-
critical P-value Bias Bias% RMSE
Ma 0.14 0.13 88 0.87 1.99 0.39 0.09 9.2 0.01
Nd 0.07 0.07 78 1.17 1.99 0.24 0.04 4.23 0.01
Tg(2005) 0.16 0.16 84 0.55 1.98 0.59 0.01 1.43 0
Tg(2008) 0.05 0.05 82 0.32 1.98 0.75 0.01 0.65 0
All 0.05 0.06 67 1.57 1.97 0.12 -0.21 -21.33 0
Ma- Mansonia altissima, Nd – Nauclea diderichii, and Tg-Tectona grandis
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Fig. 1. Predicted volume against residuals for model validation.
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DISCUSSION
The species used in this study area are typical of plantation forest. These species are very useful
for timber, pole, and pulp. Two age series of Tectona grandis which were established in 2005
and 2008 were used for this study. The tree growth variable measured in the study area showed
that mean Dbh of Mansonia altissima, Nauclea diderrichii, and Tectona grandis (Year 2005 and
2008) are 17.66cm, 10.50cm, 18.38cm and 10.73cm respectively. This implies that majority of
the trees encountered in this study area below the minimum merchantable size of 48cm stipulated
by logging policy of southwestern Nigeria (Adekunle 2002). Also, considering the sources of
error in height and stem diameter measurement, it is necessary to develop volume estimation
models using a variable, such as DBH Adekunle (2013). This method is fast, requires less work,
and is therefore cost efficient in forest inventories (Segura and Kennien2005).
Bisrod Furniture Company is one of the private forestry that still exists today. The company was
founded in the year 1958 and has two sections; Plantation section (Evergreen tree planter) and
Furniture section. The company aim to produce round wood for the furniture section of the
company. The company does not have a natural forest where wood can be exploited. Woods are
exploited from their plantation. The objective of the company is in a way different from the
primary objective of private forestry. According to (Odebiyi, 1992) the objectives of private
forestry are to encourage the development and management of forest estates as well as to
increase the quality of forest resources for enhanced living standards and environmental
protection. However, the company has contributed positively to forest development in Nigeria
through employment opportunities to the people, thus, preventing illegal felling and also through
seminars which enlightens foresters more and local people on the importance of planting trees.
In the context of sustainability, it is best to reduce the objective of investment to multifunctional
purpose on landscape basis, even though timber production may be the main objective of some
private investor. A private investor should therefore aim at improving and sustaining the quality
of life and livelihood, environmentally, socially and economically through the planting of
desirable and suitable species of trees. Numerous good and services, apart from wood, are
derivable from investment in forestry, usually beyond the contemplation of the investor. For
active participation of private sector, the need for the provision of enabling environment, the
political will and support as well as other necessary incentives are very essential (Dosunmu,
2001). The rate of deforestation and tree planting in Nigeria is difficult to estimate. In most
cases, the data is not available and the rates vary from state to state. However, nobody can
dispute the fact that the rate of deforestation is far higher than that of tree planting. In the light of
these circumstances, there is need to plant more and more trees in Nigeria especially in the
country. Indigenous communities feel resentful and unsatisfied by the government action by
keeping their forest without allowing them to benefit from the natural resources. This could
encourage deforestation. (Embaye, 2001) stated that the private sector has a major role to play in
the collection and distribution of tree seeds and planting stock. However, these goals are still far
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from being accomplished considering the fact that only government agencies have been majorly
involved in forest development in Nigeria. It is however important that individuals, groups, non-
governmental organization and local communities should also be involved in forest development.
If these goals are met, private forestry initiative can help to boost forest development in the
country by supplementing productions from state owned forests.
Model was developed for volume estimation of trees in evergreen tree planter. All the
assessment criteria revealed of the model had a good fit. The statistical fits were generally good.
Student t-test was used for validation. The result revealed that there were no significant
differences between observed and predicted volumes. The conformity to regression assumptions
when tested with the probability plot of residual and predicted values conformed to the
observation of Ajit (2010). The scatter-plots were consistent with the results of other statistical
indices for validation. This shows that the regression assumptions were not violated (Adekunle et
al., 2013). Other tree growth modelling studies, including (Andreassen and Tomter, 2003; Zhao
et al., 2004; Trasobares and Pukkala, 2004; Sonmez et al., 2009) also observed no constant
variance of residuals, an inevitable phenomenon for forest populations due to the nature of the
growth process.
CONCLUSION
This study has given in sight strategy on how private forestry can effectively contribute to forest
development in Nigeria. Also, the study has helped to gather information that provides one of the
bases for taking important decision in forestry and enabled us to access/determine the growth
rate and yield of individual trees being worked upon within the plantation. The result of the
volume estimation revealed that more volume per hectare was recorded for Tectona grandis than
Mansonia altissima and Nauclea diderrichii established the same year. This is as a result of high
fertility of the soil (soil type) and several silvicultural practices during early growth rate. Also,
the entire model used for this study gave good assessment criteria but logarithm model was
ranked first due to its high coefficient of determination f-ratio. Logarithm model could therefore
be used for management context and future studies.
References
Adekunle, V.A.J., 2002. Inventory techniques and models for yield and tree species assessment
in Ala and Omo Forest Reserve, southwestern Nigeria. PhD Thesis, Department for
Forestry and Wood Technology, Federal University of Technology, Akure. 170p
Adekunle, V.A.J., Nair, K.N., Srivastava, A.K and Sing N.K., 2013. Model and form factors for
stand volume estimation in natural forest ecosystem: a case study of Katarniaghat
Wildlife Sanctuary. Journal of Forestry Research, 24: 217–226.
Ajit, S., 2010. Estimation and validation methods in tree volume and biomassmodelling:
statistical concept. National Research Centre for agro forestry, Jhansi, India 18p,
Amaro, A., 1998. Modelling dominant height growth fir Eucalyptus. Forest Science, 4: 37−46.
International Journal of Scientific and Education Research
Vol. 3, No. 03; 2019
http://ijsernet.org/
www.ijsernet.org Page 22
Andreassen, K, and Tomter, SM., 2003. Basal area growth models for individual trees of Norway
spruce, Scots pine, birch and other broadleaves in Norway. Forest Ecology &
Management, 180, 11-24.
Avery, E.T and Burkhart H.E., 2002. Forest Measurements, 5th Edition. New York, USA:
McGraw-Hill Higher Education, p 456.
Cooper, R.A and Weekes A.J., 1983. Data, Models and Statistical Analysis. Oxford: Daniel, V.,
Helm J.A and Baker F.S., 1979. Principles of silviculture.2nd edition McGraw-Hill
Book company, pp. 500.
Dosunmu MA. (2001). Private sector participation in Forestry in Nigeria: The eggua experience
in L. Popola. J.E Abu and P.I Oni (eds) proceeding of 27th Annual conference of The
Forestry Association of Nigeria held in Abuja, FCT 17th-21st Sept.200. pp 340-345
Eboh, E., 2005. Harnessing Renewable Resource Sector for economic prosperity. Paper
presented at Economic workshop organized by AIEA and Department of International
Development Abuja 22nd June 2005.
Embaye, K., 2001. Bamboo Forest in Ethiopia: Preservation, sustainable use and management
strategy to improve seedling performance. Department of short rotation forestry,
Swedish University of Agriculltural sciences,Uppsala,Sweden.pp5
Faleyimu., 2009. Strategies of development of private forestry in Nigeria. Proceeding of the
22nd forest association of Nigeria, pp.167-176
Gadow, K.V and Hui G.Y., 1998. Modelling forest development. Dordrect: Kluwer Academic
Publishers, pp. 213.
Gwadu, A.A., 2001. Private sector participation in Forestry in Nigeria. The Eggua experience in
Popoola L., Abu J.E and Oni P.I (eds),Proceeding of 27th Annual conference Association of
Nigeria .Held in Abuja,17th-21st Sept.2001, pp. 346-355.
Husch, B., Beers, T.W. and Kershaw JrJA., 2003. Forest Mensuration. 4th edition. John Wiley
and Sons, Inc.
Kaosta, A.A., 1995. Sharing the benefit and cost of forest conservation. TDRI Quarterly Review,
10, 11-19.
Ladipo, O., 2010. An Agricultural Atlas of Nigeria, Oxford University press. Nigeria, pp. 248.
Neter GO, Kutner MH, Nachtsheim J and Wasserman W 1996.Applied linear statistical
methods, Chicago, USA: R. D. IrwinnInc.
International Journal of Scientific and Education Research
Vol. 3, No. 03; 2019
http://ijsernet.org/
www.ijsernet.org Page 23
Nwoboshi LC.1986.Meeeting challenges of deforestation in Nigeria through effective
reforestation.In. Oguntala,A.B.(ed). The challenges of deforestation in Nigeria, pp.
225-239. Philips Allan Pub. Ltd, pp. 400.
Odebiyi, J.B., 1992. Mobilizing private sector investment for forestry in Nigeria. A seminar topic
in partial fulfillment of Master of Agric.Tech. (Forestry) at Federal University,
Akure.
Rupšys, P. and Petrauskas, E., 2010. Development of q-exponential models for tree height,
volume and stem profile. International Journal of the Physical Sciences 5, 2369–2378.
Sayer, J.A., Harcourt, C.S. and Collins, N.M., 1992. The conservation atlas of Tropical forests:
Africa Macmillian Publisher Ltd, pp. 288.
Segura, M. and Kennien A., 2005. Allometric models for tree volume and total above ground
biomass in a tropical humid forest in Costa Rica. Journal of Biological tropical, 37:
2–8
Sönmez, T, Ercanli I, Kele S. 2009. A distance-independent basal area growth model for oriental
spruce (Piceaorientalis(l.) Link) growing in mixture with oriental beech
(Fagusorientalis, Lipsky) in the Artvin Region, North-East Turkey. African Journal of
Agricultural Research 4, 740–751.
Trasobares, T. and Pukkala T., 2004. Using past growth to improve individual-tree diameter
growth models for uneven-aged mixtures of PinussylvestrisL. And PinusnigraArn. In
Catalonia, north-east, Spain. Annals. Journal of Forest Science, 61: 409–417.
Vanclay, J.K., 1994. Modelling forest growth-applications to mixed tropical forests.CAB
International, Department of Economics and Natural Resource, Royal Veterinary and
Agricultural University Copenhagen, Denmark, Wallingford, UK, p.312.
Zhao, D., Borders, B. and Wilson M., 2004. Individual-tree diameter growth and mortality
models for bottomland mixed-species hardwood stands in the lower Mississippi
alluvial valley. Forest Ecology and Management, 199: 307–322.