Open Journal of Forestry
2012. Vol.2, No.4, 232-239
Published Online October 2012 in SciRes (http://www.SciRP.org/journal/ojf) http://dx.doi.org/10.4236/ojf.2012.24029
232
Native Woody Plants Diversity and Density under Eucalyptus
camaldulensis Plantation, in Gibie Valley,
South Western Ethiopia
Shiferaw Alem*, Jindrich Pavlis
Faculty of Forestry and Wood Technology, Mendel University, Brno, Czech Republic
Received July 30th, 2012; revised September 3rd, 2012; accepted September 18th, 2012
The aim of the study was to assess the impact of E. camaldulensis plantation established in a semi-arid
area on native woody plants diversity and density. Nested quadrant plot design, having an area of 15 m ×
15 m used to collect data. Totally, 37 species at the plantation and 30 species at the native woodland, be-
longing to 24 families, identified. Species diversity (H′) was 1.57 at the plantation and 2.09 at the wood-
land forest. As for density of understory woody plants (height ≥ 1 m) the plantation forest harbored 6, 604
stems/ha while the native woodland had 7347 stems/ha. Seedling density (height < 1 m) at the native
woodland and at the plantation there were 11,436 stems/ha and 8865 stems/ha, respectively. The similar-
ity of woody species composition between the woodland forest and the plantation was low. However, in
terms of autochthonous tree seed bank availability, authentic hypothesis seems to prove that if clear-cut
patches replanted by introduced species that do not exceed 5 ha, they still significantly favour original
forest regeneration and composition in a semi-arid area and surprisingly favors the regeneration of Do-
donaea angustifolia and other native species important for soil conservation, timber, bee forage and me-
dicinal use.
Keywords: Eucalyptus camaldulensis; Plantation; Diversity; Natural Regeneration; Semi-Arid; Woodland
Introduction
To relieve the shortage of wood caused by the extensive de-
forestation, eucalypts were introduced into Ethiopia in 1894-
1895 from Australia (Pohjonen & Pukkala, 1990). Nowadays
eucalypts are amongst the most successful of the introduced
plantation species, being quickly adopted by farmers, and
widely distributed throughout developing tropical countries.
The reason to be widespread is attributed to their fast growth,
coppicing ability and less management requirements, the un-
palatability of leaves, and their adaptability to a wide range of
site conditions (Turnbull & Pryor, 1978; FAO, 1981). Planta-
tion forests can provide shelter, reduce edge effects, increase
connectivity between forest fragments, and accommodate eco-
tone specialist and generalist forest species that might benefit
from any forest type (Christian et al., 1998; Norton, 1998;
Davis et al., 2001; Georgie et al., 2007; Richard et al., 2007;
Felton et al., 2010).
Even though plantations do have such and many other uses,
intensive monocultures of exotic plantations are widely viewed
in a negative light mainly in relation to biological diversity
conservation (Carnus et al., 2003). Though, it is not necessarily
true in all cases as further proved by presented study. Among
Eucalyptus, Pinus, and Tectona, which are the most commonly
used species for plantation purpose throughout the world,
Eucalyptus has attracted by far the most criticism (Evans, 1992;
FAO, 2001), arguing that Eucalyptus spp.: 1) do not provide
valuable organic matter but deplete soil nutrients; 2) pump up
water resources used for agricultural crops; 3) suppress ground
vegetation by secretion of allelopathic chemicals, and results in
unsuitable soil erosion control because of the less undergrowth
vegetation (Jagger & Pender, 2000).
On the other hand research on the tropical forest plantations
indicated that they may occasionally promote the recruitment,
establishment and succession of native woody species by func-
tioning as foster ecosystems (Parrotta, 1997; Lugo et al., 1993).
Some regeneration studies on plantations of Eucalyptus globu-
lus, Eucalyptus saligna, Eucalyptus grandis, Pinus patula, Pi-
nus radiata, Cupressus lusitanica and Grevillea robusta estab-
lished at localities with high amounts of rain-fall and in rela-
tively high altitudes of Ethiopia, also proved a surprising cata-
lytic role of these monocultures with regard to habitat recolo-
nization by native woody plants (Shiferaw & Tadesse, 2009;
Eshetu & Olavi, 2003; Feyera et al., 2002; Feyera & Demel,
2001; Eshetu, 2001; Bone et al., 1997; Colin & Lauren, 1996;
Isabele et al., 2008). However, studies on the regeneration of
native woody plants under other plantation species suitable for
dryer and low rainfall areas in lower altitudes are scarce.
The general aim of this study was to evaluate the potential
role of exotic plantation species, in facilitating natural regen-
eration of woody plants in the semi-arid conditions of Ethiopia.
With particular objective to assess naturally regenerated woody
species diversity and density in E. camaldulensis plantation
established at a degraded land in comparison with its neighbor-
ing autochthonous Terminalia-Combretum woodland.
Materials and Methods
Site Description
The study was conducted in the Abelti-Gibie forest priority
*Corresponding author.

S. ALEM, J. PAVLIS
area (8˚10'N, 37˚34'E, 1493 m above sea level) in Gibie valley
of the Oromia state, southwestern part of Ethiopia (Figure 1).
The physical feature of the study area is characterized by a
rugged topography, and dominated by gentle slopes and a lo-
calized steep slopes ranging from 1% - 27%.
The climate character influencing the study area is derived
from the closest climatologic station, (Jimma), which is situated
100 Km southwest from the locality. The area prevails uni-
modal type of rainfall pattern, with the highest rain occurring
between June and August. The mean annual temperature was
22.6˚C, with a mean minimum of 15˚C to mean maximum of
30.34˚C. The hottest months occur from March to May (maxi-
mum 30.39˚C), while coldness occurs from September to No-
vember (minimum 20.13˚C).
History of the Plant a ti on
The Eucalyptus plantation was established in the year 1983.
Originally it was planted in a 2 m × 2 m spacing although at the
time of data collection its average tree density was 524 trees/ha.
In the second and third year of its establishment the weeds un-
der the plantation were removed through slashing. The planta-
tion was established in 4 cell units, ranging from 5 to 10 ha,
inside of the autochthonous woodland. The average tree diame-
ter in the plantation was 15.58 cm and its mean height was
10.34 m, having a basal area of 15.79 m2/ha. The E. camaldu-
lensis plantation is located about 3 km away from Abelti Vil-
lage and highway asphalt road connecting Addis Ababa city to
Jimma town dissects it in to different patches. The human and
livestock pressure was minimum in the investigated plantation
and neighboring woodland areas.
Sampling Desi gn a n d Data Collection
Sampling Design
In total, 30 major sample plots, with an area of 225 m2 for
each, were laid out along line transects. In each of the native
woodland and the plantation forest 15 plots were sampled, in-
dependently. The distance between the consecutive plots along
a line transect was 200 m, and the spacing between two adja-
cent transect lines was also 200 m. At each of the major square
shaped plots (15 m × 15 m), five subplots (2 m × 2 m) were
established to investigate natural seedling recruitment. Four of
these subplots were designed and established at the corners of
the major plots, and the last one in its center. A compass was
used to align the transects.
Vegetation Data Collection
Woody species were determined and their diameter at breast
height (DBH), of all trees at the sample plot, has been measured
using a caliper and recorded in a data collection sheet. The
height of the trees, were measured using hypsometer. Seedlings
(height < 1 m) data of woody species were collected in the five
sub plots established within the major plot. Species identifica-
tion in the field (90%) has been based on expert knowledge,
using tree identification field guide manuals (Azene, 2007;
Fichtle & Admasu, 1994). For specimens being difficult to
identify in the field (10%), voucher samples were collected,
pressed and identified in the National Herbarium of Ethiopia,
Addis Ababa University.
Figure 1.
Map of the study area.

S. ALEM, J. PAVLIS
Data Analyses
Vegetation Structure and Diversity
The Shannon-Wiener Diversity Index (H′) was used to de-
termine diversity of species in both the natural forest and plan-
tation (1).
1
ln
S
i
i
i
H
pp


 (1)
where S is the number of species, pi, the proportion of the indi-
vidual species to the total, i nN.
The equitability (evenness) of species in E. camaldulensis
plantation and the neighboring native woodland was calculated
using max
HH , where is ln (natural logarithm) of S
(number of species).
max
H
Moreover, a paired t-test was used to compare the species
diversity (H′) of each plot in the native woodland and plantation
forest (SAS, 2003). In this analysis, the diversity index (H′) for
each major plot of the native woodland and the tree plantation
was considered as a replication. Vegetation data collected from
each major plot of the native woodland and plantation forest
were used for structural analysis. The seedling data was also
analyzed in a hectare base. Similarity index of understory re-
generated native woody species in the plantation and native
woodland was calculated using Jaccard’s similarity coefficient
(Krebs, 1989). In order to evaluate the distribution of a species
in the native woodland and plantation forest, the Importance
Value Index (IVI), which is a sum of relative values of density,
frequency and dominance, was also calculated for each species
(Kent & Cooker, 1994).
In the IVI analysis only 41 tree species reached the DBH
height or higher (Table 3), while the List of identified species,
containing a total number of 43 species, includes also species
under DBH threshold (Table 1).
Table 1.
List of the woody species found in E. camaldulensis plantation and the neighboring native woodland. (B = Birds, M = Mammals and W = Wind).
Native woodland E. camaldulensis plantation
No Species Trees/ha Seedlings/ha Trees/ha Seedlings/ha
Prevailing
dispersal agents
1 Acacia abyssinica 3 M
2 Acacia nilotica 9 33 18 M
3 Acacia seyal 15 600 M
4 Acacia senegal 6 M
5 Acacia tortilis 24 3 M
6 Acokanthera schimperii 3 133 M
7 Albizia gummifera 3 M
8 Calpurina aurea 3 M, B
9 Celtis africana 3 36 M, B
10 Clausena anisata 6 M
11 Combretum ghasalense 56 100 9 33 M, W
12 Combretum molle 35 M, W
13 Croton macrostachys 9 M, B
14 Deinbollia kilimandscharica 141 15 67 M
15 Dichrostachys cinerea 626 1300 212 1967 M
16 Diospyros mespiliformis 32 4567 3 33 B
17 Dodonea angustifolia 2274 4268 633 M, B
18 Dombeya schimperana 67 M
19 Dracaena afromontana 6 67 M, B
20 Ekebergia capensis 3 M, B
21 Entada abyssinica 12 33 M
22 Euclea schimperii 921 500 729 733 B
23 Ficus sur 29 26 M, B
24 Ficus vasta 3 M, B
25 Flacourtia indica 29 6 M, B
26 Fleuggea virosa 29 67 9 M, B
27 Gardenia ternifolia 766 133 M
28 Grewia bicolor 126 300 38 M
29 Grewia ferruginea 97 333 M, B
30 Maytenus gracilipes 118 433 24 267 M, B
31 Maytenus senegalensis 212 300 24 M, B
32 Millettia ferruginea 12 B
33 Nuxia congesta 3 74 33 B, W
34 Olea europaea 50 M, B
35 Oncoba spinosa 3 M
36 Piliostigma thonningii 3 M
37 Premna schimperii 41 41 M, B
38 Rhus natalensis 1465 700 447 1100 M, B
39 Schefflera abyssinica 47 3 33 M, B
40 Stereospermum kunthianum 26 6 33 M
41 Terminalia brownii 1041 2267 421 2567 M
42 Ximenia americana 21 9 M
43 Ziziphus spina-christii 6 67 15 M, B
234

S. ALEM, J. PAVLIS
Results and Discussion
Results
Floristic Composition and Diversity of Species
In total, 43 species of trees and shrubs representing 24 fami-
lies were determined in both E. camaldulensis plantation and
the neighboring native woodland (Table 1). In total we re-
corded 30 species in the native woodland and 37 species in the
plantation. Six species were recorded only within the native
woodland, while thirteen species were recorded only within the
eucalyptus plantation.
The diversity indexes (H′) of E. camaldulensis plantation and
its neighboring native woodland were 1.568 and 2.091, respec-
tively. The t-test statistics (t0.025 (28) = 2.048, tcal = 5.97) results
also revealed a significant difference in the diversity of species
(H′) between each plot of the native woodland and the E. ca-
maldulensis plantation (P < 0.02). The species distribution was
0.615 in the native woodland and 0.436 in the plantation.
Vegetation Structure and Density of Species
The relative density of trees and shrubs of 0.1 - 1 cm diame-
ter was 18.3% in E. camaldulensis plantation and 12.7% in the
neighboring native woodland (Table 2). The relative density of
trees and shrubs >12.1 cm diameter in native woodland and
plantation were 0.1% and 0.5%, respectively. The number of
tree species in the higher diameter class for both of the E. ca-
maldulensis and native woodland was less than that in the low-
er diameter class. The density of trees and shrubs (Height > 1 m)
was 7347 stems/ha in the neighboring native woodland and
6604 stems/ha in E. camaldulensis plantation, while the density
of seedlings (height < 1 m) was 11436 stems/ha in the neigh-
boring native woodland and 8865 stems/ha in E. camaldulensis
plantation. The density of trees of Terminalia brownii was
higher in the native woodland (1041 stems/ha) as compared to
Table 2.
Relative density and number of species in each diameter class in E.
camaldulensis plantation and neighboring native woodland.
E. camaldulensis plantation Neighboring native
woodland Diameter
class
(cm) Relative
density (%)
Number of
species
Relative
density (%)
Number of
species
0.1 - 1 18.3 14 12.7 14
1.1 - 2 26.5 19 27.3 20
2.1 - 3 20.9 13 19.6 23
3.1 - 4 13.7 16 17.3 22
4.1 - 5 8.9 8 12.6 21
5.1 - 6 5.3 12 6.4 17
6.1 - 7 2.7 14 2.4 11
7.1 - 8 1.5 12 0.8 8
8.1 - 9 0.6 7 0.4 6
9.1 - 10 0.6 8 0.1 6
10.1 - 11 0.4 6 0.1 3
11.1 - 12 0.1 2 0.1 3
≥12.1 0.5 5 0.1 3
E. camaldulensis plantation (421 stems/ha). Whereas, seedling
density was higher in the plantation forest (2567 stems/ha) in
comparison with the native woodland (2267 stems/ha). Some
species such as Gardenia ternifolia were recorded only at seed-
ling level in both the plantation and native woodland (Table 1).
The density of Dodonea angustifolia was much higher in the E.
camaldulensis plantation (4268 stems/ha) than in the neighbor-
ing native woodland (2274 stems/ha). Dichrostachys cinerea
had 1300 seedling stems per hectare in the native woodland and
1967 seedling stems per hectare in the plantation (Table 1).
Generally, 47.4% of the species in the E. camaldulensis planta-
tion and 47.7% of the species in the native woodland had less
than 100 seedling stems per hectare. Similarly, 68.96% and
85.29% of the identified species in the native woodland and
plantation forest had less than 100 tree stems per hectare, re-
spectively (Table 1).
Importance Values of Species
The Importance Value Index (IVI), ranges between 0.72 and
192.68 in the E. camaldulensis plantation and 6.71 and 144.92
at the neighboring native woodland (Table 3). Among the
common species found in both forest types, importance values
of A. nilotica, D. angustifolia, F. sur, N. congesta, and Z. spina-
christii were higher in the E. camaldulensis plantation than in
the native woodland (Table 3). Whereas, the IVIs of A. tortilis,
C. ghasalense, D. kilimandscharica, D. cinerea, F. indica, F.
virosa, M. gracilipes, M. senegalensis, R. natalensis and T.
brownii were higher in neighboring native woodland than in E.
camaldulensis plantation. D. angustifolia had a 100% relative
frequency in E. camaldulensis plantation and 93.33% in the
native woodland. Its relative density was 64.63% and 30.74%
in the plantation and the native woodland, respectively. Gener-
ally, D. angustifolia had a higher IVI in the plantation (192.68)
as compared to that of the native forest (144.92) (Table 3). The
species, D. cinerea and T. brownii had 100% relative frequency
in the native woodland. Of the common species identified in
both forest types 77.27% of species had higher relative density
in the native woodland than in the plantation forest. Similarly,
81.89% of the common species for both forest types had higher
relative dominance value in the native woodland as compared
with the plantation forest.
Similarity of Understory Woody Species between the Native
Woodland and the Plantation
Similarity of woody species between plots is presented in
Table 4. The minimum Jaccard’s similarity index value is
0.095, while the maximum similarity index was 0.78. The
highest similarity of species composition exists between plot 9
of the E. camaldulensis plantation and plot 1 of the neighboring
native woodland. The lowest similarity in species composition
was recorded between plot 1 of the E. camaldulensis plantation
and plot 1 of the native woodland (Table 4). Most of the plots
score a similarity index value of less than 0.50.
Discussion
Floristic Composition and Diversity of Species
More number of species were identified in the E. camaldu-
lensis plantation than in the neighboring native woodland.
However, the result of the species diversity index indicated that
the neighboring native woodland was more diverse than that of
the E. camaldulensis plantation, and the species distribution in

S. ALEM, J. PAVLIS
Table 3.
Relative density, relative frequency, relative dominance and Importance Value Index (IVI) of trees and shrubs (EC: Eucalyptus camaldulensis, NW:
Native Woodland).
No Species Relative frequency Relative density Relative dominance IVI
EC NW EC NW EC NW EC NW
1 A. abyssinica 6.67 0.04 0.13 6.84
2 A. nilotica 26.67 13.33 0.27 0.12 0.52 0.96 27.46 14.41
3 A. sayal 26.67 0.20 0.15 27.02
4 A. senegal 13.33 0.08 0.10 13.51
5 A. tortilis 6.67 33.33 0.04 0.32 0.03 2.07 6.74 35.72
6 A. schimperii 6.67 0.04 0.03 6.74
7 A. gummifera 6.67 0.04 0.26 6.97
8 C. aurea 6.67 0.04 6.71
9 C. africana 6.67 0.04 0.04 6.75
10 C. anisata 6.67 0.04 0.01 6.72
11 C. ghasalense 6.67 46.67 0.13 0.75 0.13 1.66 6.93 49.08
12 C. molle 6.67 0.47 0.94 8.08
13 C. macrostachys 13.33 0.13 1.66 15.12
14 D. kilimandscharica 20.00 60.00 0.22 1.90 0.20 2.79 20.42 64.69
15 D. cinerea 66.67 100.00 3.25 9.13 3.82 4.13 73.74 113.26
16 D. mespiliformis 6.67 26.67 0.04 0.43 0.10 1.16 6.81 28.26
17 D. angustifolia 100.00 93.33 64.63 30.74 28.05 20.85 192.68 144.92
18 D. afromontana 13.33 0.09 0.02 13.44
19 E. capensis 6.67 0.04 0.01 6.72
20 E. abyssinica 6.67 0.18 0.69 7.54
21 E. schimperii 86.67 86.67 11.05 12.37 10.42 10.49 108.14 109.53
22 F. sur 33.33 6.67 0.40 0.40 27.45 1.10 61.18 8.17
23 F. vasta 6.67 0.04 0.70 7.41
24 F. indica 13.33 26.67 0.09 0.40 0.01 0.27 13.43 27.34
25 F. virosa 6.67 53.33 0.13 0.40 0.01 0.18 6.81 53.91
26 G. bicolor 46.67 66.67 0.58 1.70 0.70 2.36 47.95 70.73
27 G. ferruginea 46.67 1.47 1.28 49.42
28 M. gracilipes 26.67 66.67 0.36 1.54 0.62 1.48 27.65 69.69
29 M. senegalensis 26.67 60.00 0.36 2.84 0.36 3.73 27.39 66.57
30 M. ferruginea 20.00 0.18 0.23 20.41
31 N. congesta 33.33 6.67 1.11 0.04 0.79 0.09 35.23 6.80
32 O. africana 40.00 0.78 0.42 41.20
33 O. spinosa 6.67 0.04 0.02 6.73
34 P. thonningii 13.33 0.43 1.53 15.29
35 P. schimperii 26.67 26.67 0.62 0.55 0.09 0.42 27.38 27.64
36 R. natalensis 100.00 100.00 6.77 19.68 11.34 16.81 118.11 136.49
37 S. abyssinica 6.67 40.00 0.04 0.63 0.01 0.59 6.72 41.22
38 S. kunthianuum 13.33 20.00 0.09 0.36 0.23 0.19 13.65 20.55
39 T. brownii 73.33 100.00 6.37 14.03 9.17 24.66 88.87 138.69
40 X. americana 20.00 20.00 0.13 0.28 0.25 0.03 20.38 20.31
41 Z. spina-christii 20.00 6.67 0.22 0.08 0.91 0.10 21.13 6.85
236

S. ALEM, J. PAVLIS
Table 4.
Jaccard’s Coefficient of similarity in species composition of naturally regenerated woody plants between sample plots of E. camaldulensis plantation
(EC) and the neighboring native woodland (NW).
Forest
type EC1 EC2 EC3 EC4 EC5 EC6 EC7 EC8EC9EC10 EC11 EC12 EC13 EC14 EC15
NW1 0.095 0.26 0.15 0.38 0.38 0.44 0.30 0.30 0.78 0.25 0.28 0.35 0.24 0.24 0.24
NW2 * 0.36 0.3 0.55 0.37 0.26 0.25 0.33 0.35 0.5 0.55 0.4 0.31 0.45 0.45
NW3 * * 0.3 0.42 0.23 0.26 0.18 0.33 0.21 0.25 0.41 0.31 0.25 0.33 0.45
NW4 * * * 0.31 0.36 0.43 0.33 0.33 0.35 0.27 0.4 0.39 0.25 0.25 0.33
NW5 * * * * 0.43 0.33 0.35 0.29 0.43 0.29 0.33 0.47 0.33 0.28 0.28
NW6 * * * * * 0.36 0.32 0.32 0.4 0.33 0.33 0.37 0.24 0.31 0.31
NW7 * * * * * * 0.28 0.44 0.44 0.38 0.33 0.41 0.26 0.36 0.36
NW8 * * * * * * * 0.25 0.27 0.33 0.29 0.37 0.24 0.24 0.31
NW9 * * * * * * * * 0.35 0.36 0.42 0.5 0.31 0.33 0.45
NW10 * * * * * * * * 0.29 0.33 0.33 0.26 0.36 0.36
NW11 * * * * * * * * * * 0.27 0.21 0.15 0.2 0.2
NW12 * * * * * * * * * * * 0.29 0.22 0.31 0.31
NW13 * * * * * * * * * * * * 0.31 0.33 0.45
NW14 * * * * * * * * * * * * * 0.33 0.33
NW15 * * * * * * * * * * * * * * 0.5
the neighboring native woodland (0.615) was more even than
that of the E. camaldulensis plantation (0.436). Even if an ab-
solute number of species was higher in the E. camaldulensis
plantation, the native woodland has a higher diversity value
which is contributed by the higher distribution of species
throughout the plots. However, in the present study, the number
of species recorded in the E. camaldulensis plantation was
higher than that recorded in other exotic plantation species in
Ethiopia. Feyera and Demel (2001) recorded a total of 18 and
11 naturally regenerated woody species under 14 years and 24
years C. lusitanica plantation within the area of the central
Ethiopian highlands. They also recorded 17, 15, 26 and 27 na-
tive woody species under 24 year P. patula, 15 year P. radiata,
26 year Juniperus procera and 17 year E. globulus plantations.
In a similar study of uneven aged plantations established in the
dry afro-mountain areas of Ethiopia, Feyera et al. (2002) re-
corded under C. lusitanica plantations 30 woody species in a 9
year old stand, 22 species in a 17 year old stand and 17 species
in a 25 year old plantation. The same author recorded for E.
globulus plantations: 16 species in a 13 year old stand, 13 spe-
cies in a 16 year old stand and 17 species in a 22 year old plan-
tation. This study also found a total of 18, 23 and 25 native
woody species in 11, 22 and 27 years of E. saligna plantation,
respectively and 18, 17 and 27 woody species in a 10, 21 and
28 years of P. patula plantation (Feyera et al., 2002).
Similarly, Eshetu and Olavi (2003) recorded a total of 22 na-
tive woody species in an 11 year E. globulus plantation in Me-
nagesha, where there was remnant natural forest, and 20 native
woody species in a 37 year old E. globulus plantation in Chan-
cho, where natural forests were absent. Likely, the number of
identified species in this study is also higher than the study
result of Eshetu (2001), under the plantations of P. patula, C.
lusitanica, J. procera, and Grevillea robusta. These differences
might be associated with the species pool available in the sur-
rounding natural forest, local climatic conditions, soil seed bank,
and effects of the plantations on the different tree species and
its density. Seed dispersal agents may also play a great role in
dispersing the seeds from the surrounding native woodlands
species pool to the E. camaldulensis plantation, in which
mammals, birds and wind were the major agents of dispersal
for the identified species in the study area (Table 1).
Vegetation Structure and Density of Species
The DBH structure of species can reveal the population dy-
namics. Therefore, based on diameter class distribution and
density, the effects of plantation and natural forests on the re-
cruitment of different species can be inferred. With increase in
diameter class, the number of species decreased both in native
woodland and E. camaldulensis plantation considerably (Table
2). Therefore, in both of the native woodland and the E. ca-
maldulensis plantation, the tree species in lower diameter
classes are dominant. Trees in the higher diameter classes are
few in the E. camaldulensis plantation, which might be due to
the age of the plantation, or the growth nature of identified
species. Although receiving low amounts of rainfall, relative
density of trees/shrubs identified in the E. camaldulensis plan-
tation was higher as compared with other findings from other
plantations of C. lustanica, E. globulus, E. saligna, G. robusta,
J. procera, P. patula, P. radiata, in the central and southern
Ethiopia (Eshetu, 2001; Feyera et al., 2002; Feyera & Demel,
2001). This difference might be associated with the low relative
density of E. camaldulensis plantation (524 trees/ha) in the
present study site as compared with the other studies, in which
low density of overstory trees allowed more light and more
open spaces to the undergrowth woody plants. Georgie et al.
(2007) stated that light levels are positively associated with
vascular plant species richness and permanent open spaces in
plantation forests provide an opportunity for enhancing biodi-

S. ALEM, J. PAVLIS
versity in the plantations. The undergrowth woody plants might
be also favored by the plantation age and rotation in which
there was no thinning and continuous harvesting of the planta-
tion. Mitschka (2002), indicated that earlier thinning or longer
rotations strongly affects biodiversity.
Some species, such as T. brownii, R. natalensis, and E.
schimperii, have a relatively higher number of seedling densi-
ties in E. camaldulensis plantation, compared to those in the
native woodland (Table 3). This result may indicate that these
species are not threatened at all by any allelopathic compounds
from E. camaldulensis plantation as it is often the case of Eu-
calyptus and/or can tolerate shade. It may even indicate that, as
an over story tree, the E. camaldulensis plantation fosters the
natural regeneration of these species. Scientific evidences indi-
cated that, some eucalypt plantations have the potential in en-
hancing the recruitment, establishment, and successions of
certain native woody species (Loumeto & Huttlee, 1997; Eshe-
tu, 2001; Feyera et al., 2002; Mulugeta & Demel, 2004). On the
other hand, some species which are well distributed throughout
in their diameter classes in the native woodland were not re-
corded in the E. camaldulensis plantation. This may show that
E. camaldulensis plantation may have a negative effect on the
undergrowth of some species, while it favors the others, which
can be related to light demanding nature of the species as for
regeneration and growth, allelopathic effect, microclimate,
competition etc. The E. camaldulensis plantation was found
favoring D. angustifolia, much better than the native woodland,
which can be used for soil conservation. This can indicate that
D. angustifolia is one potential species to regenerate under E.
camaldulensis plantation in semiarid areas, increase the ground
cover, and can help to reduce soil erosion and can increase
biodiversity in the plantation.
Importance Values of Species
The IVI is considered to show greater ecological significance
in plant distribution than in absolute density (Fosberg, 1961). D.
angustifolia found in E. camaldulensis plantation has higher
IVI and basal area than that in the native woodland. This indi-
cates that the plantation favors the distribution of this plant
species in its understory. Also, the IVI result indicated that the
E. camaldulensis plantation perhaps facilitated and fostered the
distribution of A. nilotica, F. sur, N. congesta, and Z. spina-
christii. While, A. tortilis, C. ghasalense, D. kilimandscharica,
D. cinerea, F. indica, F. virosa, M. gracilipes, M. senegalensis,
R. natalensis and T. brownii were better distributed in the
neighboring native woodland than in E. camaldulensis planta-
tion.
Similarity of Understory Woody Species between the Native
Woodland and the Plantation
The present study indicated the least similarity of woody
species composition between the native woodland forest and E.
camaldulensis plantation. This might be due to the climatic
conditions of the area, the available species pool in the sur-
rounding native woodland forest, and impact of the plantation
in its underneath woody vegetation. The findings of this study
resonate with former studies conducted in Ethiopia (Feyera et
al., 2002; Eshetu, 2001; Feyera & Demel, 2001), which re-
ported low similarity among different plantations and neighbor-
ing natural forests. The age of the plantation, the light intensity
reaching the forest floor and the amount of annual rainfall may
influence understory plant distribution.
Conclusion
All the results indicated, the plantation being established in a
degraded and semiarid area, harbored significant number of
indigenous woody species in its underneath canopy. Many of
these autochthonous trees are important for their timber pro-
duction capacity, bees forage, medicinal or soil conservation
potential, being also found at neighboring native woodland or
under other plantations of higher rainfall regime areas. Authen-
tic data seems to prove that smaller clear-cut patches, replanted
by introduced species, still significantly favor original forest
regeneration and composition. Thus, E. camaldulensis planta-
tion forest, when it is established with wider spacing, can allow
more light to reach to the understory, and serve as a nurse tree,
intern plays a role in biodiversity conservation in a semiarid
area and to rehabilitate degraded lands.
Acknowledgements
This study was financed by Forestry Research Center, Ethio-
pian Institute of Agricultural Research (EIAR), and Interni
Grantova Agentura (IGA) of Mendel University in Brno (with a
project code of 52/2010). The authors would like to acknowl-
edge Genene Tesfaye, Yiheyis Tadesse and Solomon Bacha for
their support in data collection. Thanks also to Ashenafi Burka,
for his support in preparing map of the study area.
REFERENCES
Azene, B.T., Beánie, A., & Tengnas, B. (2007). Useful trees and shrubs
for Ethiopia: Identification, propagation and management for 17
agro-climatic zones. Nairobi: Regional Land Management Unit.
Bone, R., Lawrence, M., & Magombo, Z. (1997). The effect of Euca-
lyptus camaldulensis (Dehn) plantation on native woodland recovery
on Ulumba mountain, southern Malawi. Forest Ecology and Man-
agement, 99, 83-99. doi:10.1016/S0378-1127(97)00196-5
Carnus, J. M., Parrotta, J., Brockerhoff, E. G., Arbes, M., Jactel, H.,
Kremer, A., Lamb, D., Hara, K. O., & Walter, B. (2003). Planted fo-
rests and biodiversity. UNFF Inter-Sessional Experts Meeting on the
Role of Planted Forests in Sustainable Forest Management, Wel-
lington, 25-27 March 2003, 54.
Christian, D. P., Hoffman, W., Hanowski, J. M., Niemi, G. J., & Beyea,
J. (1998). Bird and mammal diversity on woody biomass plantations
in North America. Biomass and Bioenergy, 14, 395-402.
doi:10.1016/S0961-9534(97)10076-9
Colin, A. C., & Lauren, J. C. (1996). Exotic tree plantations and the
regeneration of natural forests in Kibale national park, Uganda. Bio-
logical Conservation, 76, 253-257.
doi:10.1016/0006-3207(95)00124-7
Davis, A. J., Huijbregts, H., & Krikken, J. (2001). The role of local and
regional processes in shaping dung beetle communities in tropical
forest plantations in Borneo. Global Ecology and Biogeography, 9,
281-292. doi:10.1046/j.1365-2699.2000.00189.x
Eshetu, Y., & Olavi, L. (2003). Indigenous woody species diversity in
Eucalyptus globulus Labill. ssp. globulus plantations in the Ethiopian
highlands. Biodiversity and Conservation, 12, 567-582.
doi:10.1023/A:1022483700992
Eshetu, Y. (2001). Diversity of naturally regenerated native woody
species in forest plantations in the Ethiopian highlands. New Forests,
22, 159-177. doi:10.1023/A:1015629327039
Evans, J. (1992). Plantation forestry in the tropics (2nd ed.). New York:
Oxford University Press.
FAO (1981). Eucalypts for planting: FAO forestry and forest products
studies 11. Rome: FAO.
238

S. ALEM, J. PAVLIS
FAO (2001). State of the world’s forests. Rome: FAO.
Felton, A., Knight, E., Wood, J., Zammit, C., & Lindenmayer, D.
(2010). A meta-analysis of fauna and flora species richness and ab-
undance in plantations and pasture lands. Biological Conservation,
143, 545-554. doi:10.1016/j.biocon.2009.11.030
Feyera, S., & Demel, T. (2001). Regeneration of indigenous woody
species under the canopy of tree plantations in central Ethiopia.
Tropical Ecology, 42, 175-185.
Feyera, S., Demel, T., & Bertake, N. (2002). Native woody species
regeneration in exotic tree plantations at Munessa-Shashemene forest,
Southern Ethiopia. New Forests, 24, 131-145.
doi:10.1023/A:1021201107373
Fichtl, R., & Admasu, A. (1994). Honeybee flora of ethiopia. Mann-
heim: Benedict press.
Fosberg, F. R. (1961). A classification of vegetation for general pur-
poses. Tropical Ecology, 2, 1-28.
Georgie, F. S., Susan, I., Daniel, L. K., Saoirse, O., & Fraser, J. G.
(2007). Enhancing vegetation diversity in glades, rides and roads in
plantation forests. Biological Conservation, 136, 283-294.
doi:10.1016/j.biocon.2006.12.001
Isabele, A., Christian, M., & Andre, B. (2008). Can plantations develop
understory biological and physical attributes of naturally regenerated
forests? Biological Conservation, 141, 2461-2476.
doi:10.1016/j.biocon.2008.07.007
Jagger, P., & Pender, J. (2000). The role of trees for sustainable man-
agement of less favored lands: The case of eucalypts in Ethiopia.
Washington: International Food Research Institute.
Kent, M., & Coker, P. (1994). Vegetation description and analysis: A
practical approach. Hoboken: John Wiley and Sons.
Krebs, C. J. (1989). Ecological methodology. New York: Harper and
Row Cop.
Loumeto, J., & Huttel, C. (1997). Understory vegetation in fast growing
tree plantations on savanna soils in Congo. Forest Ecology and
Management, 99, 65-81. doi:10.1016/S0378-1127(97)00195-3
Lugo, A. E. (1992). Tree plantation for rehabilitating damaged lands in
the tropics. In: M. K. Wali (Ed.), Environmental rehabilitation (pp.
247-255). Hague: SPB Academic Publishing.
Mitschka, J. H. (2002). Rationale and methods for conserving biodiver-
sity in plantation forests. Forest Ecology and Management, 155, 81-
95. doi:10.1016/S0378-1127(01)00549-7
Mulugeta, L., & Demel, T. (2004). Restoration of native forest flora in
the degraded high lands of Ethiopia: Constraints and opportunities.
Ethiopian Journal of Science, 27, 75-90.
Norton, D. A. (1998). Indigenous biodiversity conservation and planta-
tion forestry: Options for the future. New Zealand Forest, 43, 34-39.
Parrotta, J. A., Turnbull, W. J., & Jones, N. (1997). Catalysing native
forest regeneration on degraded tropical lands. Forest Ecology and
Management, 99, 1-7. doi:10.1016/S0378-1127(97)00190-4
Pohjonen, V., & Pukkala, T. (1990). Eucalyptus globulus in Ethiopian
forestry. Forest Ecology and Management, 36, 19-31.
doi:10.1016/0378-1127(90)90061-F
Richard, H. L., Edward, G. M, Phoebe, M., & Philippa, N. (2007).
Eucalypt plantations as habitat for birds on previously cleared farm-
land in south-eastern Australia. Biological Conservation, 137, 533-
548. doi:10.1016/j.biocon.2007.03.012
SAS (2003). SAS system software. Version 9.1. Cary, NC: SAS Institute
Inc.
Shiferaw, A., & Tadesse, W. (2009). A comparative assessment on
regeneration status of indigenous woody plants in Eucalyptus gran-
dis plantation and adjacent natural forest. Journal of Forestry Re-
search, 20, 31-36. doi:10.1007/s11676-009-0006-2
Turnbull, J. W., & Pryor L. D. (1978). Choice of species and seed
source. In W. E. Hillis & A. G. Brown (Eds.), Eucalyptus for wood
production (pp. 6-65). Adelaide: CSIRO.