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Berhan International Research Journal of Science and Humanities
(BIRJSH), 2021, 5(1), 101-134
Journal homepage: www.journals.dbu.et ISSN: 2414-2794
The International Research Journal of Debre Berhan University, 2021
Effects of exotic plantation expansion and management intervention on
woody plant species diversity, regeneration and soil seed bank in Tarmaber
district, Ethiopia
Melese Bekele 1*, Dessie Assefa 2 and Yohannis Gebremariam 3
1Amhara Agriculture Research Institute, Debre Birhan Agriculture Research Center, Ethiopia
2Department of Natural Resource and Environmental Science, Bahirdar University, Ethiopia
3Department of Forestry and Environmental Science, Gondar University, Ethiopia
Abstract
This study was carried out to determine the effect of plantation forest with management
intervention on woody plant species diversity in Tarmaber district north shewa zone Ethiopia,
regeneration and soil seed bank species composition in five different forest types. A total of 75
circular sample plots of 314 m2 were established along a transect lines. Soil seed bank analysis
was done from soil samples collected in each of the plots (225 samples). Different diversity
index and ANOVA was used in SPSS software for analysis. The result showed that a total of
51 woody plant species was recorded in adjacent natural forest (41), managed C. lusitanica
(27), not managed C. lusitanica (9), managed E. globules (22) and not managed E. globules
(13) species. Regeneration of seedlings were 3538, 5567, 707, 1462 and 2524 mean stems ha-
1 for natural forest, managed C. lusitanica, not managed C. lusitanica, managed E. globules
and not managed E. globules respectively. Unmanaged C. lusitanica plantations had
significantly lower densities of mature tree stems ha-1 as compared to managed C. lusitanica,
managed E. globules and adjacent natural forest (F=14.03, p<0.05). Similarly in terms of
sapling density ha-1 unmanaged C. lusitanica was significantly lower from other forest types
(F=7.37, p <0.05). However managed C. lusitanica had significantly higher seedling
regeneration (stem density ha-1) than other plantation and adjacent natural forests (F = 16.11,
p < 0.05). Generally mean stem densities including tree, sapling and seedling of woody species
among different forest types managed C. lusitanica was significantly higher among different
forest types (F= 13.01, p<0.05). From the soil seed bank a total of 22 plant species (20 native
and 2 exotic) species were recovered. In different forest types the number of species recorded
was in adjacent natural forest (19), managed C. lusitanica (11), unmanaged C. lusitanica (4),
managed E. globules (7) and unmanaged E. globules (5). Generally with appropriate
management intervention undergrowth vegetation and soil seed bank status in plantation forest
had good species composition and diversity.
Keywords: Floristic diversity, Management intervention, Natural forest, Plantation forest, Soil
seed bank
*Corresponding author email: me121bekele@gmail.com
Article information: Received 05 February 2021; Revised 10 September 2021; Accepted 02 November 2021
© 2021 Debre Berhan University. All rights reserved.
Bekele et al., BIRJSH, 2021, 5(1), 101-134
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101
Introduction
To overcome the shortage of wood caused
by extensive deforestation, plantation forest
with exotic tree species like Eucalyptus,
Cupressus and pinus were started in
Ethiopia since 1894- 1895 (Shiferaw &
Jindrich, 2012) and are the most
successfully introduced and widely
distributed plantation throughout the
country (Markus, 2012). The reason to be
widespread is attributed to their fast growth,
and their adaptability to a wide range of site
conditions (Abrham et al., 2011).
Even though plantations have many
economic and environmental benefits,
intensive monoculture exotic plantations
are widely viewed negatively mainly in
relation to biological diversity conservation,
and undergrowth regenerations (Carnus et
al., 2006). For example, scientific and
community stake holders argued that
Eucalyptus species do not provide valuable
organic matter, deplete soil nutrients, pump
up water resources used for agricultural
crops, suppress ground vegetation by
secretion of allopathic chemicals, and
unsuitable soil erosion control because of
the less undergrowth vegetation (Becerra et
al., 2018; Sekaleli, 2012; Tilashwork,
2009).
Although it has criticism on its negative
impact for environment, Eucalyptus,
Cupressus, and Pinus are the most
commonly used species for plantation
purpose throughout the world (Sean &
Robert, 2003).
A study on the tropical forest
plantations indicated that they may rarely
promote the recruitment, establishment and
succession of native woody species by
fostering ecosystems (Parrota, 1992).
Different studies on plantations of
Eucalyptus globulus, Eucalyptus saligna,
Eucalyptus grandis, Pinus patula, Pinus
radiata, Cupressus lusitanica and Grevillea
robusta established in high rainfall and
relatively high altitudes of Ethiopia also
proved a catalytic role of these monoculture
plantation with regard to habitat re-
colonization by native woody plants
(Shiferaw & Jindrich, 2012; Feyera &
Demel, 2003). Management intervention on
exotic plantation to foster the undergrowth
vegetation and the upper canopy to make
productive the harvestable yield and
substitute regeneration is important
(Gilman et al., 2016). Because, the different
management interventions avoid
competition of light, nutrient and moisture
the upper canopy trees and undergrowth
vegetation (Williams, 2015).
Most farmers and expert’s dealing the
negative impact on expansion of exotic
plantation forests concerning ecological
and environmental issues in the study area.
Bekele et al., BIRJSH, 2021, 5(1), 101-134
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102
However, studies on the regeneration of
native woody plants under plantation forest
with management intervention and feelings
of local people about exotic plantation
forest in ecological dilemma have limited
information in the study area. The general
aim of this study is to evaluate the potential
effects of exotic plantation with
management intervention on the natural
regeneration of woody plants and the
insight of local people about exotic
plantation expansion interaction to the
environment in order to synthesize truth
information and to verify the dilemma
about plantation forest in the highland part
of North Shewa Zone, Ethiopia.
Materials and methods
Study area description
The reason behind the selection of
Tarmaber district was the existence of huge
plantation forests on the study area both
state forest and private woodlot plantation
as well as an adjacent natural forest in
similar agro-ecology. The forest is
currently owned by Amhara Forest
Enterprise. In Tarmaber plantation forest
different management intervention was
involved by the government and the
community before Amhara Forest
Enterprise established to produce quality
timber and fuelwood collection from the
part of branches. The other management
interventions involved was enrichment
planting on left lands under the plantation
forest stand using different indigenous tree
species. Generally this research was
conducted under five different forest types
such as managed Cupressus lusitanica
(pruning management involved),
unmanaged Cupressus lusitanica (no
pruning management involved), managed
Eucalyptus globules (enrichment planting
involved by different indigenous tree
species like Juniperus procera), not
managed Eucalyptus globules ( no
enrichment planting involved by
indigenous tree species) and adjacent
natural forests.
Data collection method
Quantitative approaches were used to
address the objective of this research.
Quantitative approaches to research are
based on formal, objective, and systematic
processes in which data are numerically
quantified. Quantitative approaches are
objective, deductive, and based on numeric
quantification and generalization of results.
The regeneration, diversity, density and
structure of the forest data was collected
using quantitative data collection method.
Whereas the insight of local people about
the trend of plantation expansion, impacts
on environment was used qualitative data
collection method.
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103
Figure 1. Map of study area
Vegetation data collection
Vegetation inventory was carried out in five
forest types, such as adjacent natural forest,
managed and unmanaged Cupressus
lusitanica and Eucalyptus globulus
plantation forest. The vegetation data
collection was conducted by applying a
nested plot design using a line transects
survey. All sample plots were located at
least 10 m far from the forest boundary or
roadside to avoid border effect (Yvette &
David, 2002). A circular plot was
established at specified intervals along the
transect line both in natural forest and
managed and unmanaged plantation forests,
based on using the distance between
transect and sample plots for each forest
types (Table 1). The first transect and
sample plot was placed randomly at one
side of each forest types, while the other
sample plots laied at specified intervals
from each other (Fikadu et al., 2014). The
trees were measured in the 10 m radius,
saplings in 5 m radius sampling plot and
seedlings were measured in 3 m radius in a
concentric circle (Shiferaw & Jindrich,
2012). The plants was categorized as
seedlings (height <1.0 m and DBH <2 cm)
saplings (height between 1 and 3 m and
DBH <10 cm) and tree (height >3 m and
DBH ≥10 cm) (Feyera et al., 2002; Feyera
& Demel, 2003; Ayanaw & Gemedo, 2018).
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104
Height and diameter were measured by
hypsometer and calliper respectively and
the tree which had large diameter was
measured by tape meter. Additionally,
aspect, altitude and slop were recorded on
each plot. A total of 75 sampling plots, 15
for each forest types were used along the
study area and to increase precision and to
make easy for analysis for each forest types
equal sample plot was used. In each plot, all
of the naturally regenerated woody species
were identified and counted. Species
identification and verification were done by
referring the Flora of Ethiopia and Eritrea
(Edwards et al.,2000) and natural database
for Africa (NDA) on CD-ROM version 2.0,
August 2011 (Ermias, 2011). Note: the
configuration of the transect was based on
the elevation of the area by classifying low
(2800 m), medium (3000 m) and highest
elevation (3200m) relative to the land
feature (Gillison & Brewer, 2014).
Soil sampling for soil seed bank
In order to determine species composition,
diversity, the vertical distribution as well as
the similarity of aboveground flora in the
soil seed bank soil samples was collected.
A total of 225 soil samples were collected
from the above surface layer and the soil
depth of 0-5 cm and 5-10 cm both from the
plantation forests and adjacent natural
forests (Maranon, 1998). The soil seed bank
samples were collected from the plots used
for vegetation sampling. At the centre of
each plot, a small plot of 20 cm x 20 cm
(400 cm2) was marked and collected soil
seed bank sample from the three separate
soil layers to investigate depth distribution
of seeds in the soil. The soil samples were
put into plastic bags separately and
transported to Debre Birhan Agricultural
Research Center for analysis. In cases of
dissimilarity between soil and aboveground
flora, soil depth was used to speculate the
seed sources, whether recently dispersed
seed or from the soil seed bank.
There are various methods involved in
determining soil seed bank which has been
adopted by many authors. These are a
seedling emergence method, the sieving
and floating methods (Eyob, 2006). The
seedling emergence method is the most
frequently used, and the more reliable
method, in soil seed bank studies
(Esmailzadeh et al., 2011; Gomaa, 2015).
The emerging method was best compared
to other methods because a seed which is
not visible in the mixed soil samples by
naked eyes can be observing the physical
morphology of the seedlings (Wagner et al.,
2003). Others identification methods are
not commonly used and are time
consuming, ineffective at finding small-
seeded species and may overestimate the
viable seed bank by including non-viable
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105
seeds (Savadogo et al.,2016; (Colin &
Lauren, 1996).
Table 1. Characteristics of the plantation and adjacent natural forest stands and sampling
procedures at Tarmaber Amhara forest enterprise forests
After transported the soil sample to the
Debre Birhan Agricultural Research Center,
all soil samples were sieved using a mesh
size of 0.50 mm to recover seeds of woody
species and to facilitate the germination
process of the seeds, the soil samples were
incubated in the glass house for four
months (Figure 3) (Teketay, 2005). Then
finally seedlings were identified, recorded
and discarded once every two weeks using
local reference material (Teketay, 2005).
Those seedlings emerged from the soil seed
bank in the glass house difficult to identify
were transplanted and grown to a larger
stage to make identification easier and
accurate (Teketay, 2005). However, in this
study, there were no such problems faced
because the identification of seedlings was
done by using both combinations of
taxonomic experts and local peoples who
were lived in the surrounding area.
Data analysis
Descriptive and inferential statistics were
used for data presentation and analysis.
MS-Excel was used for data organization of
the forest tree density, relative abundance,
species richness, and evenness. Analysis of
Forest types
Forest
area
(ha)
No. of
transects
Sample
plot in
each
transect
No.
sample
plot
Distance
between
transect
Age of
the
forest
Distance
between plot
(m)
Natural
forest
15
3
5
15
200m
unknown
50
Managed
C.
lusitanica
38.5
3
5
15
400m
> 30 yr.
100
Not
managed
C.lusitanica
41
3
5
15
400m
> 30 yr.
100
Managed E.
globules
23
3
5
15
200m
> 30 yr.
100
Not
managed
E.globules
69
3
5
15
400m
> 30 yr.
150
Total
186.5
75
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106
Variance (one way ANOVA) was carried
out using SPSS program version 25 to test
the effect of plantation forest with and
without management intervention and
adjacent natural forest on diversity and
regeneration status and role of soil seed
bank for regeneration. During the ANOVA
test, the number of species, stem density
and the soil seed bank community was the
dependent variables while the study
treatments or plantation forest types with
management intervention and adjacent
forest were considered as the independent
variables which were a determinate factor
for the above listed dependent variables.
Data were checked for homogeneity of
variances to assess the equality of variances,
while normality was checked in the test and
some data parameters are not normal, then,
data were log transformed.
Vegetation Data Analysis
Species diversity and richness in Tarmaber
plantation with different management
intervention and the adjacent natural forest
were calculated using the Shannon-Wiener
diversity index (H’), Shannon evenness
index and Margalef index (R) to evaluate
species richness (Peet, 1974).
……… Eq. (1)
Where, H’ is Shannon diversity index, Pi is
the proportion of individuals or the
abundance of the ith species expressed as a
proportion of a total cover, K is the number
of species and ln is log basin.
The most common and widely used
methods for evenness or equitability is
based on Pielou (1966) as follows
………………Eq. (2)
Where, J is evenness,
H’ is Shannon-wiener diversity index and
H’max is the maximum Shannon-wiener
diversity indexes
(Margalef, 1958)…Eq. (3)
Where, R is Margalef index of species
richness, S’ is number of species and N is
number of individuals
Structural data analysis
The forest structure would describe in terms
of frequency, dominance, basal area per
hectare, important value index
determination in the following formulas:
Density determination: - species density
was summarized from a total number of
individual abundance in each species. It
was calculated as follows,
Density
x100 Eq. (4)
Frequency: - the frequency of quadrates
occupied by a given species. It was
calculated in the following formula
Frequency
x100
Eq. (5)
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107
Relative Density (RD): is defined as the
number of all individuals of a given species
divided by the total number of all
individuals of all species times100.
Relative Density
x100
Eq. (6)
Relative Dominance: the area occupied by
a given species relative to the total area
occupied by all species, where dominance
is defined as the mean basal area per tree
times the number of trees of the species.
Relative Dominance
Eq. (7)
Relative Frequency (RF): is the distribution
of one species in a sample relative to the
distribution of all species.
Relative frequency
Eq. (8)
Important Value Index (IVI): It is an index
which describes the structural role of a
species in a stand and all woody species
population was examined by estimating
frequency, relative frequency, density,
relative density, dominance and relative
dominance (Pichette and Gillespie, 1999).
It was calculated as follows based on Kent
and Coker, 1992).
V I ()
=++ Eq. (9)
Where, RD is Relative Density, RF is
Relative Frequency and RDO is Relative
Dominance
Population Structure: Population structure
of tree stem diameter distribution was used
to infer regeneration patterns and
successional trends in tree population. To
determine the population structure,
individuals of each species encountered
were grouped in to a diameter class and
structure of the species was shown using
frequency class of diameter and height
distribution. According to Peters (1996)
frequency class was important to interpret
the indication of the regeneration status of
the forest.
Regeneration Status: the regeneration
status of woody species was summarized
based on the total count of seedling,
saplings and mature tree stem ha-1 of each
species across all quadrates and presented
in tables and frequency histograms.
Similarity index
The similarity analysis is used to identify
the highly similar and/or dissimilar stands
in their understory plant composition. Most
of the time similarity is analyzed using a
statistical measure of similarity coefficient
of Sorensen and Jaccard’s similarity
coefficients. But Jaccard’s similarity
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108
coefficient is most sensitive for extreme
error for small sample sizes (Chao et al.,
2005). Due to this reason Sorensen
similarity coefficient was used to compare
the similarity between the forest types in
their species richness and to test soil seed
bank community and above ground flora
similarity for this research. The index is
widely used because it gives more weight
to the species that are common to the
samples rather than to those that only occur
in either sample. The similarity (Ss) index
was calculated using the formula according
to Kent & Coker, 1992).
…….. Eq.(10)
Where, Ss is Sorenson similarity coefficient
b is number of species in sample1 a is
number of species common to both samples
c is number of species in sample 2
Results and discussion
Woody species diversity
Species Area Curve
Species area curve shows that the
relationship between the area and the
number of species found within that area
and it is very important to determine the
sufficiency of the sample plot (Scheiner et
al., 2000). The species area curve was
developed from 75 sample plots, which
covered an area of 2.355 ha. In the case of
plantation forest with management
intervention and adjacent natural forest, the
pattern of the curve shows an increasing the
number of woody species in the starting
phase with increasing areas up to a 2198 m2,
3454 m2, 4082 m2, 3140 m2 & 3140 m2 for
natural forest, managed C. lusitanica, not
managed C. lusitanica, managed E.
globules and not managed E. globules
respectively. And this assumption is
scientifically true, when the species
diversity increased with the increasing of
area (Lawson & Henrik, 2006). Also in this
study, the numbers of species become
constant after above points for each forest
types and made curve flat (Figure 5).
Normally based on curve formation, it
confirmed that 15 sample plots for each
forest types were sufficient and it can
represent the entire population and
generated good information about the
composition, diversity and species richness
in the study area (Khaine et al., 2017).
Floristic composition
For this study, list of the naturally
regenerated woody species in managed and
unmanaged plantation forests and the
adjacent natural forest stand had a total of
51 woody species with 31 families and
1265 individuals were recorded (Table 2).
The present study both in adjacent natural
and plantation forest were (i.e. 51 species),
which were close to the Munessa-
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109
Shashemene forest (i.e.55 species) reported
by Feyera & Demel (2002). And it had
higher number of species compared to
Menagesha-Suba dry Afromontane forest
(i.e. 42 species) reported in central Ethiopia
(Feyera & Demel, 2001).
Figure 2. Species-area curve of all species in managed and unmanaged Tarmaber plantation
forest and adjacent natural forest.
The higher number of species recorded in
this study under plantation forest and
natural forest compared to Menagesha-
Suba dry Afromontane forest could be due
to the reason of environmental difference,
human and animal interference, and altitude
difference among the forests. Since
Munessa-Shashemene and Menagesha-
Suba dry Afromontane forest found in the
altitude of 2200 to 3000 m. a .s, whereas
this study was conducted at 2800 to 3500 m.
a.s. The life form of the plants according to
the classifications of Getachew & Biruk
(2014), among 51 native woody species 17
species were trees, 36 were shrubs, and 6
species were shrub/woody climbers .
The species composition in different forest
stands ranged from 9 to 41 species in the
study area. The number of species recorded
in unmanaged C. lusitanica plantation was
9 species, whereas in managed C. lusitanica
plantation 27 species were recorded. Also
in unmanaged E. globules plantation
(without enrichment planting) and managed
E. globules (with enrichment planting) had
13 and 22 species respectively. However in
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110
adjacent natural forest 41 species was
recorded and highest among other
plantation forests. The highest number of
species was found in the natural forest stand,
which confirms to the results from previous
studies in Yeraba priority state forest,
Amhara Region, Ethiopia (Getachew &
Biruk, 2014). Whereas among plantation
stands, the highest number of species was
recorded in managed C. lusitanica (with
pruning management intervention)
plantation stand and the least numbers of
species are recorded in not managed C.
lusitanica (without pruning management
intervention) plantation in the study area.
This result also confirmed by (Bauhus &
Schmerbeck, 2010) the effect of
management on diversity. Least number of
species recording in not managed C.
lusitanica is in line with the study of
Abrham et al. (2011) under Cupressus and
Eucalyptus species low understory plant
recruitments were recorded in cupressus
plantation than eucalyptus plantation
without any enhancing management
interventions. Such variations are attributed
to standing canopy characteristics that
determine the number of canopy gaps
available for solar radiation, which
influences the environmental conditions at
the forest floor such as light and air and soil
temperatures.
Species Frequency Class
Frequency expresses how frequently the
species is observed in all samples. In other
words it explains its distribution over the
Figure 1 Frequency diagram of woody species in managed and unmanaged plantation forest and
adjacent natural forests. A (natural forest), B (Managed C. Lusitanica), C (Not managed C.
lusitanica), D (Managed E. globulus) and E (Not managed E. globulus)
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111
forest (Kebede et al., 2013). In this study
plantation forest with management
intervention and adjacent natural forest tree
species were categorized under five
frequency classes according to Raunkiaer’s
frequency classes (Robert, 1962) (Figure 6).
High number of species were found in
frequency class of 1-20%) and 21-40%) and
it gradually decreases the number of species
in frequency class of 41-60%), 61-80%)
and class (81-100%). This result indicated
that more than 80 % of the species found in
the absolute class of 1-20% and 21-40%,
which means that high value in the lower
frequency classes and low values in the
higher frequency classes indicated that high
floristic heterogeneity occurred, but the
reverse of this result displayed similar or
constant species composition (Abyot et al.,
2014).
Frequency: The most frequently found
species (frequency ≥50%) are described for
each forest types. In natural forest (10),
managed C. lusitanica (5), in not managed
C. lusitanica (2), managed E. globules (2)
and in not managed E. globules (3) species
were recorded in this study (Table 3). The
remaining species found less than 50%
frequency and the minimum frequency for
each forest types in 75 quadrats was 7%.
This means out of the 75 sampled quadrates
these species were encountered only in
seven quadrants. This implies that these
particular species are rare relative to the
other species and may become nonexistent
from the study forest in the future
(Getachew & Biruk, 2014).
Species diversity, richness and density
The highest mean number of species was
found in the natural forest (15±0.65)
followed by managed C. lusitanica (8±1.05)
and the least mean number of species was
recorded at unmanaged C. lusitanica
(2±0.18) (Table 4). There was a significant
difference between forest types (F=62.43,
p< 0.05). Similar results reported by
Shiferaw & Tadesse (2009) in Belete state
Table 2. Family of the dominant woody species
in Tarmaber plantation forest and adjacent
natural forest at Tarmaber North Shewa Zone,
Ethiopia
No.
Family
No of
Species
No of
Individuals
1
Asteraceae
5
73
2
Lamiaceae
3
19
3
Myrsinaceae
3
40
4
Rosaceae
3
36
5
Rubiaceae
3
50
6
Anacardiaceae
2
18
7
Cupressaceae
2
396
8
Melianthaceae
2
15
9
Moraceae
2
33
10
Solanaceae
2
105
Others 11-31
24
480
Total
51
1265
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112
forest and Abrham et al. (2011) in
Tehuledere district showed natural forest
have more number of species than
plantation forest.
Depending on this result managed C.
lusitanica and natural forest was highly
significantly differed between them and
other unmanaged plantation forests types
(F=62.43, p< 0.05 (Table 4). Similar results
Table 3. List of the most frequently found species (F ≥50%) in all sampled stands at
Tarmaber plantation forest and in adjacent natural forests in North Shewa Zone, Ethiopia
Forest types
Species name
Local name
Frequency
(%)
Natural forest
Allophylus abyssinicus
Embus
53
Discopodium penninervum
Ameraro
80
Dovyalis abyssinica
Koshem
53
Galiniera saxifrage
Yetota kula
80
Juniperus procera
Habesha tisde
93
Maesa lanceolata
Kelewa
87
Maytenus arbutifolia
Atate
87
Morus mesozygia
Injory
60
Olea africana
Woyera
73
Vernonia auriculifera
Gujo
93
Managed C. lusitanica
Cupress lusitanica
Yefereje tisd
87
Discopodium penninervum
Ameraro
93
Erica arborea
Aseta
73
Juniperous procera
Habsha tisd
80
Vernonia auriculifera
Gujo
60
Not managed C. lusitanica
Erica arborea
Aseta
87
Juniperous procera
Habesha tsid
50
Managed E. globules
Discopodium penninervum
Ameraro
53
Juniperous procera
Habesha tsid
100
Not managed E. globules
Erica arborea
Aseta
93
Lobelia rhynchopetalum
Jibra
67
Pentas schimperiana
Woyinagifet
60
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113
also reported in Vietnam by Millet et al.
(2013).
Table 4. Woody species along plantation forest with management intervention and adjacent
natural forest (F=62.43, p=0.000; n= 15)
Forest types
Mean ±SE
SD.
Min
Max
CV%
Natural forest
15±0.65c
2.52
11
20
17
Managed C. lusitanica
8±1.05b
4.05
1
14
51
Not managed
C. lusitanica
2±0.18a
0.70
1
4
33
Managed E. globules
5±0.38a
1.51
2
7
34
Not managed
E. globules
4±0.53a
2.07
1
8
50
Sig (5%)
**
Table 1: Species richness computation using Margalef index (R) and Shannon diversity
index in different forest stands in Tarmaber forest North Shewa Zone, Ethiopia
No.
Treatments
S
N
Diversit
y (H’)
Evenness
(H’/lnS)
R (Margalef
richness index)
1
Natural forest
41
359
3.32
0.89
6.80
2
Managed C. lusitanica
27
409
2.25
0.68
4.32
3
Not managed C. lusitanica
11
52
1.29
0.59
2.03
4
Managed E. globules
22
211
1.83
0.33
3.92
5
Not managed E. globules
13
233
1.8
0.70
2.20
Table 2: Mean stem density ha-1 in managed and unmanaged plantation forest and
adjacent natural forests (ANOVA, F=13.01, p=0.000, n= 15).
Variables
Forest types
Mean± S.E
SD.
Min
Max
Stem density ha-1
Natural forest
762±83.64bc
323.95
414
1465
Managed C. lusitanica
868±99.92c
386.99
382
1592
Not managed C. lusitanica
110±11.09a
42.94
32
191
Managed E. globules
450±58.05b
224.80
191
924
Not managed E. globules
494±115.47b
447.23
64
1497
Sig (5%)
**
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114
Enrichment planting of native species in a
logged tree plantation increases the number
of tree species in the understory vegetation.
In addition, Jennifer & Alistair (2013)
reported that silvicultural activities like
pollarding, pruning and coppicing enhance
vegetation regeneration plant species
composition under exotic plantation forests.
This is because silvicultural treatment
affects soil and water content and nutrient
availability and sunlight penetration that
create an opportunity for understory
vegetation growth. So from this study, the
number of species increases from
unmanaged plantation forest to managed
plantation forests and to natural forest. Also
in comparison of plantation forest and
natural forest in woody species
regeneration with appropriate management
interventions like seed source or planting
materials, availability of remnant patch
natural forests and dispersing agent made
increasing the number of species. But with
absence of these management activity
clamming plantation forest for negatively
on species abundance and composition is a
wrong way in scientific and local
communities in different parts of the world
(Bernes et al., 2014).
The Margalef richness indices Table 5
confirmed that the natural forest stand was
richer in regenerated species than
plantation stands (R=6.8). And among
plantation forest stands managed C.
lusitanica stand was richer than others
(R=4.32). Not managed E. globules and C.
lusitanica had the least species richness
(R=2.2 and 2.03) respectively (Table 5).
The existence of rare species made the
richness result higher in the natural forest
and 13 species were found in a natural
forest and these were not found on the
plantation stands. Among plantation stands,
the C. lustanica and E. globules with
management intervention contained 10
more species, which were not found in
natural forest.
Shannon diversity index (H’) is taking
in to account the number of individuals as
well as the number of species. Shannon
diversity varies from 0 for a community
with only a single species to a high value
for a community with many species and in
theory, this can reach very large values.
However, in practice for biological
communities, H’ does not exceed 5.0
(Krebs, 1999 as cited in Alemayehu, 2002).
Shannon diversity index is high when it is
above 3.0, medium when it is between 2.0
and 3.0, low between 1.0 and 2.0, and very
low when it is smaller than 1.0 (Cavalcanti
and Larrazabal, 2004 as cited in Temesgen
et al., 2015). From this study, the natural
forest showed high diversity; managed C.
lusitanica had medium diversity and the
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115
unmanaged plantation forest had low
diversity (Table 5).
And the species evenness ranges from zero
0 to 1, with zero signifying no evenness and
one, a complete evenness (Pielou, 1966).
From this study all forest types had high
evenness (Table 5) except managed E.
globules had low evenness (0.33) values,
because it might be biased from some
important group of species during
enrichment planting. This reason was
similar in the study of species diversity by
artificial restoration for coniferous forests
in Southwest China (Qiaoying et al., 2006).
Generally in this study more or less even
representation of individuals of all species
encountered in the studied quadrants except
a few species are dominant.
There was a significant difference in
the mean stem density of woody species
among the different forest types (F= 13.01,
p<0.05). Not managed C. lusitanica forest
was significantly lower than other forest
types. Whereas the managed C.lusitanica
plantation is significantly higher than other
forest types except the adjacent natural
forest (Table 6). From this result with
appropriate management intervention in
plantation forest can enhance species
composition, species diversity and good
regeneration as equally as in natural forests
(Nagaraja et al., 2011). Regeneration in the
understory of the managed plantations
differed from that of an unmanaged
plantation forests. This implies that
management intervention like spacing,
enrichment planting, pruning and
pollarding can offer opportunities for
species richness (Bauhus & Schmerbeck,
2010); (Kerr, 2015); (Petit & Montagnini,
2006).
Similarity in species composition
between different plantation forests and
adjacent natural forest
The similarity in species composition of the
plantations to the natural forests could
determine the plantations that eventually
undergo secondary succession to be
replaced by indigenous woody species that
closely resemble the floristic composition
of the natural forest. The results of the study
showed that the not managed C. lusitanica
plantation exhibited the least similarity in
species composition to the natural forest
and other managed plantations, while the
managed C. lusitanica plantation was the
most similar to the natural forest (Table 7).
The similarity indices determine if the
composition of a future secondary forest
that replaces the plantation forest would be
similar to the natural forest (Pande et al.,
1988).
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116
The similarity in species composition
between the five forest types was ranged
from the similarity index values of 0.312
(between managed E. globules forest and
not managed C. lusitanica plantation forest)
to 0.653 (between managed C. lusitanica
and managed E. globules plantation forests)
(Table 7). Generally, natural forest and
managed plantation forest have high
similarities which, most of the forest types
had a score of a similarity index value
between 0.407-0.653. This result also is
inline with Shiferaw & Tadesse (2009) in
the study of a comparative assessment on
regeneration status of indigenous woody
plants in Eucalyptus grandis plantation and
adjacent natural forest in Belete state forest.
From the total similarity index values, the
better similarity was observed between
managed C. lusitanica and managed E.
globules plantation forests because these
forests were located close to each other or
there were either similar seed dispersal
mechanisms or the forests could have
similar soil seed banks (Omoro &
Luukkanen, 2011).
Basal Area: The basal area distribution is
very important criteria for determining and
classifying forest types and often
important for forest management decisions
such as estimating forest regeneration
(Hökkä et al., 1997). Total woody species
basal area among the forest types of the
study area was high in the natural forest
(27.56 m2 ha-1) and low in an unmanaged C.
lusitanica plantation forest (0.18 m2 ha-1)
(Figure 7). The comparison of the total
basal area of the adjacent natural forest had
a higher basal area to plantation forest.
Generally, in this study, the basal area of
adjacent natural forest was very low even
when it compared to the basal area of
Table 3: Sorenson’s similarity index and the number of common woody species
composition between the different forest types (* the lowest similarity, ** the highest
similarity).
Forest types
Natural
forest
Managed
C.
lusitanica
Not
managed
C.
lusitanica
Managed
E.
globules
Not managed
E. globules
Natural forest
0.588
0.320
0.590
0.407
Managed C. lusitanica
0.444
0.653**
0.55
Not managed
C.lusitanica
0.312*
0.545
Managed E. globules
0.388
Not managed E.
globules
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117
tropical forests 35 m2 ha-1 (Midgley &
Niklas, 2004). However, it had a greater
basal area, which reported from Bale
Mountain National park, Boditi Forest ( 23
m2 ha-1) (Yineger et al.,2008); Zengena
Forest (22.3 m2 ha-1) (Tadele et al.,2014)
and Hugumburda forest (9.23 m2 ha-1)
(Aynekulu, 2011). Among plantation
forests, the managed stands of plantation
forests had a higher basal area with relative
to an unmanaged plantation forest (Figure
7). The management effect on the basal area
among plantation forest had good
indication of natural regeneration in terms
of basal area and number of species
compared to unmanaged plantation stands.
Similar studies conducted in Britain
showed that the use of silvicultural systems
like pruning, pollarding and coppicing
enhance the biological diversity of
indigenous tree species basal area and good
regeneration under plantation forest (Kerr,
2015). Other studies conducted enrichment
planting of indigenous tree species in
plantations forest in Costa Rica was found
to be more successful in tree stem
regeneration and good basal area under the
forest plantations (Petit & Montagnini,
2006).
Figure 2. Basal area of plantation forest
with and without management intervention
and adjacent natural forest
The basal area of natural regenerated plants
under plantation forest with and without
management intervention and adjacent
natural forest was classed in to five classes
(Figure 8). The number of species found in
an unmanaged plantation forest had only
basal area <1 m2 ha-1 and the managed
plantation forest and adjacent natural forest
some species had above 1 m2 ha-1 basal area
and most species had <1 m2 ha-1. This is the
reason behind the management effect that
made basal area difference across all forest
types in a similar environment and
agroecology situations. Also the number of
species in each forest types laid in the lower
basal area class, the managed plantation
stand and natural forests showed good
regeneration capacity. Nenninger et al.
(2012) also confirmed that appropriate
silvicultural treatments in plantation forests
enable to increase the productivity of the
harvestable stand in terms of mass values
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118
and it converts plantation forests of exotic
tree species into natural forests by
enhancing of undergrowth native trees
regeneration.
Importance value index (IVI)
It provides the measure of the relative
importance of the species than simple count
and species with the largest value in
dominance could be considered as the most
important species in the study area (Ajayi
& Obi, 2016).
In this study ten most important woody
species in the adjacent natural forest with
the highest import value index are
Juniperus procera Olea eurpeana, Ficus
sur, Vernonia auriculifera, Prunus africana,
Discopodium penninervum, Maesa
lanceolata, Rhus glutinosa, Maytenus
arbutifolia and Allophylus abyssinicus.
These species contributed to over 64 % of
the total import value index. Whereas in the
managed C. lusitanica plantation stand
more than 61 % of the IVI is dominated by
6 species which, are Juniperous procera,
Discopodium penninervum, Erica arborea ,
Vernonia auriculifera, Myrica salicifolia
and Hagenia abyssinica (appendix 3). In
not managed C. lusitanica plantation stand,
more than 80% of the IVI was covered by
Erica arborea and Juniperous procera. In
managed E. globules more than 64% of the
IVI was occupied by Juniperous procera
and Discopodium penninervum, and in not
Figure 3. Number of woody species in different forest types of plantation forest and
adjacent natural forests. A (natural forest), B (Managed C. Lusitanica), C (Not managed C.
lusitanica), D (Managed E. globulus) and E (Not managed E. globulus)
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119
managed E. globules plantation Erica
arborea, Juniperus procera and Hagenia
abyssinca was the most important species
in the study area. Generally, in plantation
forest with and without management
intervention and adjacent natural forest the
most important species was Juniperus
procera. Similar results were reported in
the study of Ethiopian highland forests
Juniperous procera tree species was
existed under the canopy of plantation
forest (Getachew & Biruk, 2014; Hundera,
2011; Shiferaw, 2006). Also in this study
the focus group discussion and key
informants ‘confirmed that Juniperous
procera can exist in exotic plantation forest
without inferior to the existed exotic
plantation forest stand. Because in this
study area before converting to plantation
forest scattered Juniperus procera trees
was found. And the tree had wider
agroecology (1750-3500 m) and mostly the
plant existed rocky basalt soil types (Hall,
2009).
Mean diameter and height
The mean Diameter at Breast Height (DBH)
and mean height of Tarmaber plantation
forest with and without management
intervention and adjacent natural forest was
illustrated in (Table 8). The result indicated
that the mean DBH and height of woody
species both in plantation and adjacent
natural forest had varied results due to
management effects in the plantation forest
(Table 8). The standard deviation of
diameter and height were higher because of
the variation of individual trees. This
results was confirmed by (Karlsson, 2013)
on his dessiretation in Swedish University
of Agricultural Sciences on silvicultural
regimes and early biomass thinning in
young, dense pine stands.
Diameter distribution plays a
significant role in forest science and used to
determine the optimum selective cutting
that improves the stand structure (Linares et
al., 2011). The overall distribution of
diameter classes of individuals of all the
species in the study area (Figure 9) in
natural forest, managed C. lusitanica and in
managed E. globules indicated a relatively
high proportion of individuals in the lowest
diameter class (seedlings), which ensures
the potential of recruitment of sustained
future regeneration of the forest. However,
the decline of number of individuals in the
higher diameter classes considerably
suggesting that there is unplanned and
unsustainable exploitation of woody
species in the forest by the local people for
domestic
consumption and generating income. This
result is similar to the study of Zegie, north
western Ethiopia (Alelign et al., 2007). In
an unmanaged C. lusitanica and E. globules
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120
a bell shaped distribution skewed to the
right which is normal in plantation forests
(Varga., 2015). From here, the overall
distribution of diameter classes of
individuals of all the species are dominated
by a relatively high proportion of
individuals in the lowest diameter class
(seedlings) that ensure sustained
regeneration of forests.
Like diameter distribution, the height
distributions of the study area were
performed. The height distribution in each
study forest types showed an inverse -J
shaped curve (Figure 10). The number of
stems ha-1 declined with increasing size
(height), that is, more number of
individuals at lower size classes and very
few numbers of individuals in the high
height classes. Generally this pattern of
height distribution indicated that good
regeneration status of the Forest (Tadele,
2004).
Natural regeneration
Figure 4. Diameter frequency distribution of Woody species of in managed and unmanaged
plantation forest and adjacent natural forests. A (natural forest), B (Managed C. lusitanica), C
(Not managed C. lusitanica), D (Managed E. globulus) and E (Not managed E. glo
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121
The highest regeneration mean density of
mature tree woody species was higher in the
natural forest followed by the managed C.
lusitanica and least regenerate mean
density of mature tree stem ha-1 was
recorded in not managed C. lusitanica
plantation stand among different forest
types.
Tukey’s post hoc analysis showed that the
mature tree regenerate mean density in not
managed C. lusitanica and E. globules had
significantly lower from the mean density
of the other managed plantation forest and
adjacent natural forest (F=14.03, p<0.05).
This can possibly be attributed to the lack
of nutrient availability, sun-light and
moisture stress due to competition. for
example, other studies carried out in
Cupressus lusitanica plantations in Kibale,
Uganda found that the managed Cypress
plantations had high species diversity and
stem density ha-1 indigenous trees under the
canopy of plantation forest stand (Colin &
Lauren, 1996). Saplings of woody tree
species are one of the parameters to
evaluate the regeneration performance of
Figure 5. Height frequency distribution of Woody species in managed and unmanaged
plantation forest and adjacent natural forests. A (natural forest), B (Managed C. Lusitanica),
C (Not managed C. lusitanica), D (Managed E. globulus) and E (Not managed)
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122
the plantation and adjacent natural forests
(Dupuy & Chazdon, 2006). The natural
forest had the highest regenerate mean
density of saplings (Table 9) followed by
managed C. lusitanica and E. globules
stems ha-1. The lowest regenerate mean
density of saplings was recorded in the not
managed C. lusitanica stem ha-1. There
were significant differences in regeneration
between the not managed C. lusitanica
plantation forest with that of managed
plantation forest and unmanaged E.
globules and adjacent natural forest
(F=7.37, p <0.05).
Also seedling is the most critical phase to
express regeneration performance among
different growth stage of trees (Balliu et al.,
2017). The managed C. lusitanica
plantation forest had the highest
regeneration of seedlings followed by
adjacent natural forest and not managed E.
globules stems ha-1 and the lowest
regenerate of seedlings was recorded in not
managed C. lusitanica stand. This
Table 4: Mean diameter and mean height of Tarmaber plantation forest with management
intervention and adjacent natural forest at Tarmaber North Shewa Zone Ethiopia
Forest types
N ( sample
tree
population)
Variables
Mean ± SE
Min
Max
SD.
Natural Forest
209
DBH
(cm)
20.51±1.86
2
115
26.83
209
Height
(m)
12.54±1.02
2
43
14.73
Managed
C. lusitanica
173
DBH
(cm)
8.53±0.65
2
44.6
8.55
173
Height
(m)
6.55±0.51
2
28
6.71
Not managed
C. lusitanica
22
DBH(cm)
6.22±0.92
2
22
4.33
22
Height
(m)
3.92±0.83
2
19
3.90
Managed
E. globulus
150
DBH (cm)
7.86±0.44
2
35
5.38
150
Height
(m)
5.36±0.33
2
19
4.01
Not managed
E. globulus
127
DBH (cm)
6.58±0.47
2
18
3.58
127
Height
(m)
3.85±0.30
2
19
3.40
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123
regeneration of seedlings showed
significantly different among the different
forest types (F = 16.11, p < 0.05).
In managed C. lusitanica plantation forest,
mean seedlings regeneration strongly
higher than all other plantation forest types
and adjacent natural forest whereas
unmanaged E. globules and C. lusitanica
and managed E. globules not significantly
Table 5. Regeneration of mean densities of mature tree, sapling and seedling in managed and
unmanaged plantation forest and adjacent natural forests (ANOVA, F=14.03, F=7.37,
F=16.11, p=0.000, n=15)
Variables
Forest types
Mean± S.E
SD.
Min
Max
Tree Density ha-1
Natural forest
154±19.88b
77.01
0
287
Managed C. lusitanica
97±19.75b
76.51
0
223
Not managed C.
lusitanica
4±2.91a
11.26
0
32
Managed E. globules
121±24.28b
94.04
0
350
Not managed E.
globules
21±10.62a
41.13
0
127
Sig (5%)
**
Sapling Density ha-1
Natural forest
1163±138.93b
538.09
382
2548
Managed C. lusitanica
1078±150.68b
583.59
0
1911
Not managed C.
lusitanica
169±42.45a
164.42
0
382
Managed E. globules
789±119.36b
462.29
0
1656
Not managed E.
globules
985±222.54b
861.89
0
3057
Sig (5%)
**
Seedling Density ha-1
Natural forest
3538±390.7b
1513.22
1769
7431
Managed C. lusitanica
5567±663.80c
2570.87
1415
9908
Not managed C.
lusitanica
707±109.19a
422.87
354
1415
Managed E. globules
1462±302.76a
1172.60
0
3185
Not managed E.
globules
2524±650.55ab
2519.56
0
8139
Sig (5%)
**
**=significant at 1% level, *=significant at 5% level, ns= not significant
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124
differed seedling regeneration between
them. This result also inline to the study of
diversity of native woody regeneration in
exotic tree plantations and natural forest in
Southern Philippines (Tulod et al., 2017).
The result in Table 9 confirmed that
managed C. lusitanica have the highest
number of seedlings among other forest
types and the number of seedlings
regeneration under plantation forest with
and without management intervention and
the adjacent natural forest was important to
indicate the management effect on
regeneration.
Figure 6. Mean density of seeds in the soil seed bank in different forest types from above
surface layer to 10 cm soil depth
When this study result compared to
assumption of the regeneration status using
the categories had good regeneration status
in all forest types that implies the number
of stems of seedling density > sapling
density> tree density (Table 9).
1. ‘Good’, if presence of seedling >
sapling > mature strata,
2. ‘Fair’, if presence of seedling >
sapling < mature strata;
3. ‘Poor’, if a species survives only in
the sapling stage, but not as
seedlings (even though saplings
may be <,> or = matured trees;
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125
4. ‘None’, if a species is absent both in
sapling and seedling stages, but
present as mature; and
5. ‘New’, if a species has no mature,
but only sapling and/ or seedling
stages (Fisaha et al., 2013).
Figure 7. Vertical distribution of viable seeds in soil depth for all forest types.
Soil seed bank and seedling emergence
The mean abundance of seeds in the study
area in different forest types from the above
surface layer to 10 cm soil depth ranged
from 77±19.13 to 252±63.92 seeds per m2
(Figure 11). The managed C. lusitanica
had the highest density of seeds followed
by adjacent natural forest, while E. globulus
plantation with enrichment plantation had
the least mean seed abundance (Figure 11).
This might be due to the different
environmental factors that affect
regeneration, such as temperature, light; pH,
burial depth, and soil moisture are known to
affect seed germination (Lu et al., 2006).
And the lowest seed density recorded in
managed E.globulus was the reason behind
the information obtained from secondary
data, the site was before converting to
plantation forest it was the cultivated land
and used for cropping purpose that is why
the plantation forest needed enrichment
planting on the left lands. Similar studies
conducted at Karei Deshe in northeastern
Israel farm and grazing lands previously
before converting grass lands and other
land uses type, the high intensity and timing
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126
of cattle grazing and cultivation changes the
size and composition of the soil seed bank,
even if after changing the land use type
(Sternberg et al.,2003).
The vertical distribution of soil seed banks
in different forest types was assessed. The
density of seeds in the soil showed similar
vertical distribution in all forest types in a
gradual decreasing along increasing soil
depth (Figure 12). Similar studies done by
Teketay & Granström ( 1995) in dry
Afromontane forests of Ethiopia showed
Table 6. Densities of seedlings in the soils of the different forest types along soil depth above
surface (F=2.493, p=0.051), 0-5 cm (F=2.98, p=0.024) and 5-10 cm (F=2.38, p=0.059, n=15)
Emerging seedling in the
soil seed bank per m2
Forest types
Mean± S.E
SD.
Min
Max
Above the surface layer of
the soil
Natural forest
145±30.88a
119.59
0
450
Managed C. lusitanica
163±37.70a
146.03
0
425
Not managed C.
lusitanica
91±15.74a
60.99
0
225
Managed E. globules
61±13.77a
53.34
0
175
Not managed E.
globules
106±23.20a
89.87
0
275
Sig (5%)
ns
0-5 cm soil depth
Natural forest
40±14.80ab
57.32
0
175
Managed C. lusitanica
61±17.40b
67.39
0
225
Not managed C.
lusitanica
16±5.27ab
20.41
0
50
Managed E. globules
11±5.90a
22.88
0
75
Not managed E.
globules
33±9.01ab
34.93
0
100
Sig (5%)
**
5-10 cm soil depth
Natural forest
23±7.09a
27.49
0
100
Managed
C. lusitanica
28±11.40a
44.18
0
150
Not managed
C. lusitanica
10±4.08a
15.81
0
50
Managed
E. globules
3±2.27a
8.79
0
25
Not managed
E. globules
11±4.13a
15.99
0
50
Sig (5%)
ns
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The International Research Journal of Debre Berhan University, 2021
127
density of soil seed bank decreased when
the soil depth is increased. The burial depth
of seeds may affect the distribution along
soil depth (Lu et al., 2006).
Other environmental factors such as light
sensitivity, chemical inhibitors, pH and
differences in seed longevity may affect
seed distribution with depth (Eyob, 2006).
Other study showed that woody species
seeds tend to accumulate due to their long-
Table 7. Soil seed bank species richness, diversity and evenness of Tarmaber plantation
forest with management intervention and adjacent natural forest
Forest type
Soil layers
S
H'
E
Natural forest
Above litter layer
19
2.59
0.88
0-5 cm
11
2.22
0.93
5-10 cm
7
1.57
0.81
Managed C.lustanica
Above litter layer
9
1.47
0.67
0-5 cm
7
1.16
0.60
5-10 cm
5
1.3
0.81
Managed E.globulus
Above litter layer
7
1.42
0.73
0-5 cm
4
1.15
0.83
5-10 cm
1
0
0.00
Not managed C.lustanica
Above litter layer
4
0.62
0.45
0-5 cm
1
0
0.00
5-10 cm
1
0
0.00
Not managed E.globulus
Above litter layer
5
1.14
0.71
0-5 cm
4
1.14
0.82
5-10 cm
3
0.8
0.72
Table 8. Similarity between soil seed bank and above ground flora (* the lowest similarity,
** the highest similarity)
Forest types
Common species
both in above
ground flora & soil
seed bank
Species
exclusive to
aboveground
flora
Species
exclusive to
soil seed bank
Sorenson’s
coefficient
similarity
values
Natural forest
19
22
0
0.633**
Managed C.
lusitanica
9
18
2
0.473
Not managed C.
lusitanica
3
19
1
0.230*
Managed E.
globules
6
16
1
0.413
Not managed E.
globules
4
9
1
0.444
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The International Research Journal of Debre Berhan University, 2021
128
lived seeds in the soil seed bank (Teketay &
Granström, 1995). However, emerging
seedlings from the soil seed bank from 5-10
cm was lower compared to the above
surface layer of the soil and 0-5 cm soil
depth, even though emerging seedlings in
different forest types were not significantly
differed among each forest types (F=2386,
p > 0.05 (Table 10).
The mean densities of emerging
seedlings in the above surface layer of the
soil were not significant among the
different forest types (F = 2.493, p > 0.05)
(Table 10). And the emerging seedlings
from soil seed bank in the soil depth of 0-5
cm was minimum relative to the emerging
seedlings from the above soil surface layer
and the results of one way ANOVA
analysis in managed E. globules was
significantly lower than other forest types
( F=2.989, P <0.05).
Species richness, diversity and evenness
of soil seed bank
The Shannon diversity index for the
diversity and evenness of soil seed bank in
adjacent natural forest, managed
C.lustanica and E.globulus plantation
forests were good as compared to
unmanaged plantation forests (Table 11). In
the five forests, there was relatively higher
diversity on the surface layer of soils
followed by 0-5 cm and 5-10 cm soil depth.
Generally, species richness decreased down
the soil layers (Table 11). Similar studies in
Mongolia China (Qian et al., 2016) showed
species richness decreased down the soil
depth.
Similarity between Soil Seed Bank and
Aboveground Flora
The similarity between the soil seed bank
and aboveground flora was ranged from
similarity index values from 0.230 for not
managed C. lusitanica plantation forest to
0.633 for natural forest (Table 13). Totally
twenty two species (20 native and 2 exotic)
woody species out of 51 species
(Allophylus abyssinicus, Bersama
abyssinica, Cupressus lusitanica,
Discopodium penninervum, Dovyalis
abyssinica, Eucalyptus globulus, Embelia
schimperi, Erica arborea, Galiniera
saxifrage, Juniperus procera, Laggera
pterodonata, Maesa lanceolata, Maytenus
arbutifolia, Morus mesozygia, Olea
africana, Phytolacca dodecandra, Prunus
africa, Rhnmnus prinoides, Rumex
nervosus, solanum dasyphyllum, Vernonia
amygdalina and Vernonia auriculifera)
were represented both in the aboveground
vegetation and in the soil seed bank.
This implies that the soil seed bank
contributed for the aboveground flora or
vice versa (Looney & Gibson, 1995). This
is because, most woody species do not
Bekele et al., BIRJSH, 2021, 5(1), 101-134
The International Research Journal of Debre Berhan University, 2021
129
accumulate seeds in the soil and only few
woody species tend to produce recalcitrant
seeds (Teketay & Granström, 1995).
The similarity between the different
soil layers was also important. Generally,
the similarity between the above surface
layer and 0-5 cm and 5-10 soil depth was
relatively higher (Table 13) however;
unmanaged plantations and managed E.
globules plantation forest had low
similarity in some soil depth layers.
Conclusion
The plantations studied were mainly
monocultures and it is suggested that
management intervention could possibly
improve the regeneration of indigenous tree
species. Different species of exotic tree
plantations with management intervention
showed variability in their understory
woody species regeneration. In comparison
managed plantations and the natural forests
to unmanaged plantations stands the exotic
tree plantations had limited effectiveness in
facilitating regeneration of indigenous
woody vegetation. The managed C.
lusitanica (pruning of branches) creates a
good opportunity for light penetration
found to be effective in facilitating woody
species regeneration as compared to the
unmanaged plantations forests.
The different species of plantation forest
varied in woody species composition,
diversity and soil attributes showing that
the over-story species affected regeneration.
The various factors that influence
regeneration such as canopy cover,
limitation of seed dispersal agents, seed
source natural forests near to plantation
forest and soil seed bank limitation and
management intervention can be linked to
the species of tree regeneration. Enrichment
planting of indigenous tree species in
plantations would enhance conservation
efforts as well as providing alternative
sources of forest resources. The soil seed
bank of the studied sites was dominated by
20 native and 2 exotic woody species and
this is the inverse of the understory
vegetation which was dominated by woody
vegetation. The proximity of natural forests
to plantations forests has been shown to
enhance the floristic diversity in plantations
and could perhaps enhance the viability of
the woody species populations in the
plantation forests.
Plantations can play an important role
in restoring the productivity, ecosystem
stability, and biodiversity of degraded
tropical lands as well as providing
economically and socially valued forest
products and services. Through careful
selection of appropriate management, the
negative effects of the plantations can be
offset while facilitating indigenous forest
regeneration. The local people perception
Bekele et al., BIRJSH, 2021, 5(1), 101-134
The International Research Journal of Debre Berhan University, 2021
130
about plantation forest expansion in
environmental and ecological issues was
positive concerning soil conservation,
biodiversity, water flow and rehabilitation
Conflict of interest
The authors declare that there is no conflict
of interest
References
Abrham, A., Mulugeta, L., Georg, G., Raf, A.,
Demel, T., & Gerhard, G. (2011). Status of
Native Woody Species Diversity and Soil
Characteristics in an Exclosure and in
Plantations of Eucalyptus globulus and
Cupressus lusitanica in Northern Ethiopia.
Mountain Research and Development, 31(2),
144-152.
Ajayi, S., & Obi, R. L. (2016). Tree Species
Composition, Structure and Importance Value
Index ( IVI ) of Okwangwo Division, Cross
River National Park , Nigeria. International
Journal of Science and Research, 5(12): 85-93.
Abyot, D., Teshome, S., Ensermu, K., &
Abiyou, T. (2014). Diversity, Structure and
Regeneration Status of the Woodland and
Riverine Vegetation of Sire Beggo in Gololcha
District, Eastern Ethiopia. Momona Ethiopian
Journal of Science, 1: 70-96.
AFE (Amhara Forest Enterprise). (2017).
Debre birhan branch Forest management Plan.
Alelign, A., Teketay, D., Yemshaw, Y., &
Edwards, S.U.E. (2007). Diversity and status of
regeneration of woody plants on the peninsula
of Zegie, northwestern Ethiopia. Tropical
Ecology, 48(1), 37-49.
Alemayehu, W. (2002). Opportunities,
constraints and prospects of the Ethiopian
Orthodox Tewahido Churches in conserving
forest resources : the case of churches in south
Gonder, northern Ethiopia MSc Thesis in
Swedish University of Agricultural Sciences,
37-55
Ayanaw, A., & Gemedo, D. (2018). Woody
Species Diversity, Structure, and Regeneration
Status of Yemrehane Kirstos Church Forest of
Lasta Woreda, North Wollo Zone, Amhara
Region, Ethiopia. International Journal of
Forestry Research, 4-7.
Aynekulu, B. (2011). Forest diversity in
fragmented landscapes of northern Ethiopia and
implications for conservation. Rheinische
Friedrich-Wilhelms-Universität Bonn.
Balliu, A., Marsic, N.K., & Gruda, N. (2017).
Seedling production.
Bauhaus, J., & Schmerbeck, J. (2010).
Silvicultural Options to Enhance and Use
Forest Plantation Biodiversity. EARTH
Ecosystem Goods, 3569: 96–127.
Becerra, P.I., Catford, J.A., Inderjit, Luce
McLeod, M., Andonian, K., Aschehoug, E.T.,
Callaway, R.M. (2018). Inhibitory effects of
Eucalyptus globulus on understorey plant
growth and species richness are greater in non-
native regions. Global Ecology and
Biogeography, 27(1): 68-76.
Bernes, C., Gunnar, J.B., Junninen, K., Lõhmus,
A., Macdonald, E., Müller, J., & Sandström, J.
(2014). What is the impact of active
management on biodiversity in forests set aside
for conservation or restoration ? A systematic
review protocol. Environmental Evidence,
22(3): 1-9.
Carnus, J.M., Parrotta, J., Brockerhoff, E.,
Arbez, M., Jactel, H., Kremer, A., Walters, B.
(2006). Planted forests and biodiversity.
Journal of Forestry, 104(2): 65-77.
Central Statistics Agency (CSA, 2007).
Chao, A., Chazdon, R., Colwell, R., & Shen, T.
(2005). A new statistical approach for assessing
compositional similarity based on incidence
and abundance data. Ecology Letters, 8: 148-
159.
Bekele et al., BIRJSH, 2021, 5(1), 101-134
The International Research Journal of Debre Berhan University, 2021
131
Colin, C., & Lauren, C. (1996). Exotic tree
plantations and the regeneration of natural
forests in Kibale National Park, Uganda.
Biological Conservation, (3): 253-257.
Dupuy, J.M., & Chazdon, R.L. (2006). Effects
of vegetation cover on seedling and sapling
dynamics in secondary tropical wet forests in
Costa Rica. Journal of Tropical Ecology, 22:
65-76.
EEPA (Ethiopian Environmental Protection
Authority) (2013). Federal Democratic
Republic of Ethiopia’s Climate Resilient Green
Economy.
EIAR (Ethiopia Impact Assessment Report)
(2011). Federal democratic republic of Ethiopia
consultancy service for detailed engineering
design, document Debre birhan - Ankober road
project environmental impact assessment report.
Edwards, S., Tadesse, M., Demissew, S., &
Hedberg, I. (2000). Flora of Ethiopia & Eritrea
Volume 2, Part 1 (2nd ed.). Addis Ababa,
Ethiopia.
Ermias.D (2011). Natural Database for
Africa(NDA ) On CD-ROM Version 2.0
Eslami, A., Karimi, B., Payam, H., &
Derakhshan, O.K. (2011). Investigation of the
structure and distribution diameter classes
models in beech forests of Northern Iran.
African Journal of Agricultural Research,
6(10): 2157-2165.
Esmailzadeh, O., Hosseini, S.M., & Tabari, M.
(2011). Relationship Between Soil Seed Bank
and Above-ground Vegetation of a Mixed-
deciduous Temperate Forest in Northern Iran.
Journal of Agricultural Science and
Technology, (13): 411-424
Eyob, T. (2006). Soil Seed Bank Study and
Natural Regeneration Assessment of Woody
Species in Dodola Dry Afromontane Forest,
Bale Mountains MSc Thesis at Addis Ababa
University.
Feyera, S., Beck, E., & Lüttge, U. (2002).
Exotic trees as nurse-trees for the regeneration
of natural tropical forests. Trees, 16(4–5): 245-
249.
Feyera, S., & Demel, T. (2001). Regeneration
of indigenous woody species under the
canopies of tree plantations in Central Ethiopia.
Tropical Ecology, 42(2): 175-185.
Fikadu, E., Melesse, M., & Wendawek, A.
(2014). Floristic composition, diversity and
vegetation structure of woody plant
communities in Boda dry evergreen Montane
Forest, West Showa, Ethiopia. International
Journal of Biodiversity and Conservation, 6(5):
382-391.
Fisaha, G., Hundera, K., & Dalle, G. (2013).
Woody plants’ diversity, structural analysis and
regeneration status of Wof Washa natural forest,
North-east Ethiopia. African Journal of
Ecology, 51(4): 599-608.
Getachew, M., & Biruk, A. (2014). Status of
native woody species regeneration in the
plantation stands of Yeraba priority state forest,
Amhara Region, Ethiopia. Journal of Natural
Sciences Research, 4(16): 91-103.
Gillison, A., & Brewer, K. (2014). The Use of
Gradient Directed Transects or Gradsects in
Natural Resource Surveys. Journal of
Environmental Management, 20: 103-127.
Gilman, A.C., Letcher, S.G., Fincher, R., Perez,
A.I., Madell, T.W., Finkelstein, A.L., &
Corrales-Araya, F. (2016). Recovery of floristic
diversity and basal area in natural forest
regeneration and planted plots in a Costa Rican
wet forest. Biotropica, 48(6): 798-808.
Gomaa, N. (2015). Soil seed bank in different
habitats of the Eastern Desert of Egypt. Saudi
Journal of Biological Sciences, 19(2), 211-220.
Hall, B. (2009). Data Sheets on Species
Undergoing Genetic Impoverishment Juniperus
Procera Hochst. Ex Endl. Morogoro, Tanzania.
Hökkä, H., Alenius, V., & Penttilä, T. (1997).
Individual-tree Basal Area Growth Models for
Scots Pine, Pubescent Birch and Norway
Spruce on Drained Peatlands in Finland. Silva
Fennica, 31(2): 161-178.
Bekele et al., BIRJSH, 2021, 5(1), 101-134
The International Research Journal of Debre Berhan University, 2021
132
Hundera, K. (2011). Status of indigenous tree
species regeneration under exotic plantations in
Belete forest, South West Ethiopia. Ethiopian
Journal of Education and Sciences, 5(2), 19-26.
Jennifer, S., & Alistair, S. (2013). The benefits
and hazards of exploiting vegetative
regeneration for forest conservation
management in a warming world, 86: 503-513.
Karlsson, L. (2013). Silvicultural regimes and
early biomass thinning in young, dense pine
stands. Doctoral Thesis Swedish University of
Agricultural Sciences.
Kerr, G. (2015). The use of silvicultural
systems to enhance the biological diversity of
plantation forests in Britain.
Kent, M. and Coker, P. (1992). Vegetation
Description and Analysis. A practical approach.
John Wiley and Sons, New York, 363.
Khaine, I., Woo, S.Y., Kang, H., Kwak, M.,
Sun, M., Youh, H., Kim, J. (2017). Species
Diversity, Stand Structure, and Species
Distribution across a Precipitation Gradient in
Tropical Forests in Myanmar. Forests, 8(282):
1-15.
Lawson, D., & Henrik, J.J. (2006). The species-
area relationship and evolution. Journal of
Theoretical Biology, 241, 590-600.
Lemenih, M., & Teketay, D. (2004).
Restoration of Native Forest Flora in the
Degraded Highlands of Ethiopia: Constraints
and Opportunities. Ethiopian Journal of
Science, 27(1): 75-90.
Linares, J.C., Carreira, J.A., & Ochoa, V.
(2011). Human impacts drive forest structure
and diversity. Insights from Mediterranean
mountain forest dominated by Abies pinsapo
( Boiss). European Journal of Forest Research,
25-40.
Looney, P., & Gibson, D. (1995). The
Relationship between the Soil Seed Bank and
Above-Ground Vegetation of a Coastal Barrier
Island. Journal of Vegetation Science, 6(6) :
825-836.
Lu, P., Sang, W., & Ma, K. (2006). Effects of
environmental factors on germination and
emergence of Crofton weed (Eupatorium
adenophorum). Weed Science, 54: 452-457.
Maranon, T. (1998). Soil seed bank and
community dynamics in an annual-dominated
Mediterranean salt-marsh. Journal of
Vegetation Science 9, 371-378.
Margalef, R.(1958). Information theory in
Ecology, Genetic and Systematic, 3: 36-71.
Markus, K. (2012). Global tree plantation
expansion review (3).
Mekonnen, A. (2016). Soil Seed Bank and
Natural Regeneration of Trees. Journal of
Sustainable Development, 9(2): 73.
Midgley, J.J., & Niklas, K. (2004). Does
disturbance prevent total basal area and
biomass in indigenous forests from being at
equilibrium with the local environment?
Journal of Tropical Ecology, 20: 595–597.
Millet, J., Tran, N., Ngoc, N ., Tran, T., & Prat,
D. (2013). Enrichment planting of native
species for biodiversity conservation in a
logged tree plantation in Vietnam. New Forests,
44: 369-383.
Minore, D., & Laacke, R. (2001). Natural
Regeneration, 11: 258-283.
Mulugeta, W. A. (2017). Assessing the value
added of forest ecosystems conservation and
plant species diversity in four key biodiversity
areas in Ethiopia. Bees for Development of
Ethiopia, (2753).
Muluneh, M. (2011). Eucalyptus plantations in
the highlands of Ethiopia revisited : A
comparison of soil nutrient status after the first
coppicing. University of Natural Resources and
Applied Life Sciences Vienna.
Nagaraja, B. C., Niki, M., & Somashekara, R.
(2011). Regeneration of native woody species
under plantations in Kudremukh National Park,
Western Ghats of South India. International
Journal of Biodiversity Science, Ecosystem
Services and Management, 7(2): 77-83.
Bekele et al., BIRJSH, 2021, 5(1), 101-134
The International Research Journal of Debre Berhan University, 2021
133
Nenninger, A., Kateb, H.El, Fetene, M., &
Mosandl, R. (2012). Silviculture Contributions
Towards Sustainable Management of
Plantation Forests in the Highlands of Ethiopia,
188.
Omoro, L.M.A., & Luukkanen, O. (2011).
Native Tree Species Regeneration and
Diversity in the Mountain Cloud Forests of East
Africa. Biodiversity Loss in a Changing Planet,
241-256.
Pande, P.K., Bisht, A.P.S., & Sharma S.C. 1988.
Comparative vegetation analysis of some
plantation ecosystems. Indian Forester, 114:
379-389
Parrota, J.A. (1992). The role of plantations
forests in rehabilitating degraded tropical
ecosystems. Agriculture, Ecosystem and
Environment, 41: 115-133.
Peet R.K., (1974). The measurement of species
diversity. Annual review of ecology and
systematic, 5: 285-307.
Peters, C.M. (1996). The ecology and
management of non-timber forest resources.
World Bank Technical paper 322.
Petit, B., & Montagnini, F. (2006). Growth in
pure and mixed plantations of tree species used
in reforesting rural areas of the humid region of
Costa Rica, Central America. Forest Ecology
and Management, 233: 338-343.
Pichette, P.R. and Gillespie. L. (1999).
Terrestrial vegetation biodiversity monitoring
protocols. Ecological monitoring and
assessment network occasional paper series.
Report No. 9. Burlington, onterio, Canada. 123-
124.
Pielou, E.C., (1966). The measurement of
diversity in different types of biological
collections. Statistical research service, Canada
department of agriculture, Ottawa, Ontario,
Canada. Theoret. Boil., 13:131-144.
Pima, N.E. (2015). Growth Performance, Water
Use and Wood Properties of Eucalypt Clones in
Tanzania. Sokoine University of Agriculture,
Tanzania.
Qiaoying, Z., Yunchun, Z., Yirdaw, E., Peng,
L., Shaoliang, Y., & Ning, W. (2006). Species
diversity based on vertical structure as
indicators of artificial restoration for coniferous
forests in Southwest China. Wuhan University
Journal of Natural Sciences, 8(4): 2006.
Qian, J., Liu, Z., Hatier, J. B., & Liu, B. (2016).
The vertical distribution of soil seed bank and
its restoration implication in an active sand
dune of northeastern Mongolia, China. Land
Degradation & Development, 27: 305-315.
Savadogo, P., Sanou, L., Dayamba, S.,
Bognounou, F., & Thiombiano, A. (2016).
Relationships between soil seed banks and
above-ground vegetation along a disturbance
gradient in the W Park trans-boundary
biosphere reserve, West Africa. Journal of
Plant Ecology Advance, 2-34.
Scheiner, S.M., Cox, S B., Willig, M.,
Mittelbach, G.G., Osenberg, C., & Kaspari, M.
(2000). Species richness, species- area curves
and Simpson’s paradox. Evolutionary Ecology
Research, 2: 791–802.
Sean, P.H., & Robert, I.G. (2003). The effect of
a teak (Tectona grandis) plantation on the
establishment of native species in an abandoned
pasture in Costa Rica. Forest Ecology and
Management, 176(1-3): 497-507.
Sekaleli, T. S. (2012). The Impact of Eucalypts
Plantation on Soil Moisture and Ground
Vegetation Cover at St. Michaels in the Roma
valley, Lesotho, 1-19.
Shiferaw, A. (2006). Regeneration of
Indigenous Woody Plants, Status of Soil
Fertility and Quality of Coffee Found in an
Eucalyptus grandis Plantation and the adjacent
Natural Forest in Southwestern Ethiopia, MSc
Thesis in Addis Ababa University, 28-44
Shiferaw, A., & Jindrich, P. (2012). Native
Woody Plants Diversity and Density under
Eucalyptus camaldulensis Plantation, in Gibie
Valley, South Western Ethiopia. Open Journal
of Forestry, 2(4): 232-239.
Shiferaw, A., Jindrich, P., Josef, U., & Jiří, K.
(2015). Pure and Mixed Plantations of
Bekele et al., BIRJSH, 2021, 5(1), 101-134
The International Research Journal of Debre Berhan University, 2021
134
Eucalyptus camaldulensis and Cupressus
lusitanica: Their Growth Interactions and Effect
on Diversity and Density of Undergrowth
Woody Plants in Relation to Light. Open
Journal of Forestry, 5: 375-386.
Shiferaw, A., & Tadesse, W. (2009). A
comparative assessment on regeneration status
of indigenous woody plants in Eucalyptus
grandis plantation and adjacent natural forest.
Journal of Forestry Research, 20(1): 32-35.
Sternberg, M., Mario, G., Perevolotsky, A., &
Jaime, K. (2003). Effects of grazing on soil seed
bank dynamics : An approach with functional
groups. Journal of Vegetation Science, 14: 375-
386.
Tadele, D. (2004). Growth and Establishment
of Seedlings of Indigenous Species inside
Plantations and the Adjacent Natural Forest in
MSc Thesis at Addis Ababa University.
Tadele, D., & Fetene, M. (2013).
Photosynthetic Responses of Seedlings of two
Indigenous Plants inside Exotic Tree
Plantations and adjacent Natural Forest in
Munessa-Shashemene Forest, Southern
Ethiopia. Momona Ethiopian Journal of
Science, 5(2): 3-14.
Tadele, D., Lulekal, E., Damtie, D., & Assefa,
A. (2014). Floristic diversity and regeneration
status of woody plants in Zengena Forest, a
remnant montane forest patch in north western
Ethiopia. Journal of Forestry Research, 25(2).
Teketay, D. (2005). Seed and regeneration
ecology in dry Afromontane forests of
Ethiopia:Forest disturbances and succession.
Tropical Ecology, 46(1): 29-44.
Teketay, D., & Granström, A. (1995). Soil seed
banks in dry Afromontane forests of Ethiopia.
Journal of Vegetation Science, 6, 777-786.
Tilashwork, C. A. (2009). The Effect of
Eucalyptus on Crop Productivity, And Soil
Properties in the Koga Watershed, Western
Amhara Region, Ethiopia MSc Thesis in
Cornell University, 6-27.
Tulod, A., Casas, J., Marin, R. A., & Ejoc, J. B.
(2017). Diversity of native woody regeneration
in exotic tree plantations and natural forest in
Southern Philippines. Forest Science and
Technology, 13(1): 31-40.
TWAO (Tarmaber woreda Agricultural office).
(2018). Tarmaber Woreda annual
Socioeconomic Survey.
Varga, A., Ódor, P., Molnár, Z., & Bölöni, J.
(2015). The history and natural regeneration of
a secondary oak-beech woodland on a former
wood-pasture in Hungary. Acta Societatis
Botanicorum Poloniae, 84(2): 215-225.
Wagner, M., Poschlod, P., & Setchfield, R.P.
(2003). Soil seed bank in managed and
abandoned semi-natural meadows in Soomaa
National Park, Estonia. Annales Botanici
Fennici, 40: 87-100.
Williams, R. A. (2015). Mitigating Biodiversity
Concerns in Eucalyptus Plantations Located in
South China. Journal of Biosciences and
Medicines, 3: 1-8.
Yineger, H., Kelbessa, E., Bekele, T., &
Lulekal, E. (2008). Floristic Composition and
Structure of the Dry Afromontane Forest at
Bale Mountains National Park, Ethiopia. SINET
Ethiopian Journal of Science, 31(2), 103-120.
Yvette, K., & David, E. (2002). Roads as edges:
Effects on vegetation in forested landscapes.
Forest Science, 48(2): 381-390.
