Species composition , Plant Community structure and Natural regeneration status of Belete Moist Evergreen Montane Forest , Oromia Regional state , Southwestern Ethiopia

Belete forest is one of the very few remnant moist evergreen montane forests in Ethiopia. The objective of this work was to study the vegetation structure, composition and Natural regeneration status of Belete moist evergreen montane forest. To investigate the plant community structure, composition and regeneration status of Belete forest, line transects were laid down on the longest transect starting from the bottom valley to the top ridge. Sample quadrats 20m x20 m, 5m x 5m, 1m x 1m were laid for trees, shrubs, sapling and seedling, and herbaceous layer respectively in a nested form. The sample quadrats were laid down along transects at a distance of 50m from each other. A total of 69 quadrats were sampled. Vegetation classification was performed using PC ORD for windows version 5.0. Five communities were recognized. Results showed that a total of 157 plant species representing 69 families and 135 genera were recorded. These were composed of 31.2% Herbs, 28.7% Trees, 26.1% Shrubs, 5.7% Climbers, 5.1% Liana, 1.9% Epiphytic herbs, and 1.3% herbaceous Ferns. The major families were Fabaceae and Asteraceae each represented by 10 species (6.4%), followed by Lamiaceae 9 (5.7%) and Rubiaceae 6 (3.8%). Other thirty three families consisting 19.8% were represented by one species only. Regeneration status of the forest was analyzed by comparing saplings and seedlings with the matured trees. Results revealed that Belete moist evergreen montane forest is at good regeneration status. Planning and management of the forest should be assisted by research findings, such as detailed ecological studies in relation to various environmental factors.


INTRODUCTION
Ethiopia has the fifth largest floral diversity in tropical Africa (Motuma Didita et al., 2010).Due to its diverse topography that has given rise to the development of wide diversities of flora and fauna rich with endemic elements.Between; 6,000-7,000 species of higher plants are estimated to exist in the country of which about 780-840 (12-13%) plant species are estimated to be endemic (Demel Teketay, 2001;Girma Balcha et al., 2004;Nune et al., 2007).
They are under severe land-use pressure, because the same environmental conditions that foster high species diversity also render tropical montane forest areas suitable for agricultural uses (Schmitt et al., 2010).Deforestation in Afromontane areas has been generally associated with increased run-off and soil erosion leading to a decline in soil fertility.The Afromontane areas of eastern Africa, including the Ethiopian highlands, constitute vivid examples of tropical forest ecosystems that have exceptional species richness, high concentrations of endemic species, and which are under great human land-use pressure.These are, therefore, internationally recognized as the Eastern montane Biodiversity Hotspot (Schmitt et al., 2010).Much of the Ethiopian highlands would bear montane forests if untouched; hence remnants of these forests still occur in the central part of the country (Tamrat Bekele, 1993).
Therefore, the objective of this paper is to present the results of the study of the vegetation structure, composition and natural regeneration status of Belete moist evergreen montane forest and provide reliable information for the development of appropriate management plan.

Study area description
Belete forest is situated in Shabe-Sombo District, Jimma zone, Oromia National Regional State, 375 km Southwest of Addis Ababa (Fig 1) and is part of the Belete Gera National forest priority area.The forest is located at longitudes between 36 0 15' E and 36 0 45' E and latitude 7 0 30 ' N and 7 0 45'N (Kitessa Hundera and Tsegaye Gadissa, 2008) and Altitude between 1,300 and 3,000 masl (Cheng et al., 1998).In Belete Forest, soils are generally fine-textured.Nitisols and Cambisols, often more than 100cm deep, occur in areas with gentle slopes and forest cover.
Leptosols are found on mountain peaks, steep slopes and stream banks where soil is shallow (less than 30cm deep).Luvisols dominate in depressions such as marshes and lowlands along rivers (Cheng et al., 1998).The mean annual rainfall of the area is between 1800 and 2300 mm with maximum rainfall between the months of June and September.The mean annual temperature of the area is between 15 0 C and 22 0 C (Kitessa Hundera and Tsegaye Gadissa, 2008).

Sampling design
To investigate the plant community structure, species composition, and regeneration status of Belete moist evergreen montane forest (BMEMF), seven line transects were laid down starting Kflay, G and Kitessa, H (MEJS) Volume 6( 1 Figure 1.Map of the study area.

2.3.Vegetation data collection
All trees, shrubs and herbs including vascular epiphytes were recorded from the systematically established quadrats along each transect.Species which were readily identifiable were recorded in the field.For species which were difficult to identify in the field, their local name were recorded, herbarium specimens were collected, pressed and dried properly using plant presses and were taken to the Jimma University Herbarium and National Herbarium of Addis Ababa University (ETH) for identification.Voucher specimens were deposited in the Herbarium of Kflay, G and Kitessa, H (MEJS) Volume 6( 1 In each quadrat identity, number, and diameter at breast height (DBH) and diameter at stump height (DSH) were measured for trees and shrubs respectively.Diameter at Breast Height was measured at 1.3 m above the ground while Diameter at Stump height was measured at 0.5 m above the ground.DBH and DSH were measured using Diameter tape.Saplings and seedlings were also identified, numbered, and measured for their DBH (For the Sapling).

Data analysis
A hierarchical cluster analysis was performed using PC-ORD for windows version 5.0 to classify the vegetation into plant community types based on abundance data of the species in each quadrat.The data matrix contained 69 quadrats and 149 species.Even though 157 specimens were collected, eight species were collected outside the quadrats for floristic composition only and are not included in structural analysis.
The indicator species in each community type were determined using Indicator Species Analysis (ISA) (Dufre´ne and Legendre, 1997).A species is considered as an indicator of a group when its indicator value is significantly higher at P < 0.05 (Tadesse Woldemariam, 2003).The clusters were designated as plant community types and given names after two or three dominant or characteristic species.

Regeneration status of the forest
Regeneration status of the forest was analyzed by comparing saplings and seedlings with the matured trees according to Dhaulkhandi et al. (2008);and Tiwari et al. (2010) Belete moist evergreen montane forest consists of 17 (10.82%)endemic species to Ethiopia some of which are included in the IUCN Red Data List (Table 1).

Vegetation classification
A total of five clusters were clearly recognized from the cluster analysis.Each plant community type is listed and described below.

Teclea noblis -Vernonia auriculifolia Community
The community had two indicator species ( Herbs such as Guizotia scarba, Rumex nepalensis and Bidens biternata are also common in this community.Peperomia tetraphylla was the epiphytic herb found in this community.

Shrub and tree density
Tree and shrub density, expressed as the number of individuals with DBH greater than 3.5 cm was 760.95/ha and those individuals with DBH between 10 and 20 cm and with DBH greater than 20 cm were 305.07ha -1 and 149ha -1 , respectively.In this case individuals less than 3.5cm were considered as seedlings.The ratio described as a/b, is taken as the measure of size class distribution (Grubb et al., 1963).Accordingly, the ratio of individuals with DBH between 10 & 20 cm (a) to DBH > 20 cm (b) was 2.04 for BMEMF.

Basal area (BA)
Total basal area for Belete moist evergreen montane forest was found to be 103.5 m 2 /ha.

Tree species population structure
The evaluation of selected tree species reveals six main patterns of population structure.These include: 1) Inverted J-shape; which shows a pattern where species frequency distribution has the highest frequency in the lower diameter classes and a gradual decrease towards the higher classes (Pouteria adolfi-friederici) which shows good reproduction and recruitment.According to Feyera Senbeta et al. (2007) Bell shape pattern indicates a poor reproduction and recruitment of species which may be associated with intense competition from the surrounding trees.

Natural regeneration of Tree species in Belete moist evergreen montane forest
The present study showed that regeneration status of BMEMF is at good regeneration status (Fig
Figure 5. Regeneration status of Belete Moist Evergreen Montane Forest.

Phyto-geographical comparisons with other moist evergreen montane forests of Ethiopia
Belete Moist Evergreen Montane Forest was compared with other montane forests in Ethiopia (Table 2).

DISCUSSION
The proportion of endemic plant species in montane forests of Ethiopia is high, Ranging between 11-15% of the total number of species (Friis and Sebsebe Demissew, 2001).This showed that BMEMF comprises high endemicity (10.82%).
It is observed in the Teclea nobilis -Vernonia auriculifolia community, most of the associated woody species occupy a shrub layer (e.g.Teclea nobilis, Coffea arabica, Galineria saxifraga) which have been found as characteristic shade tree of semi-forest coffee systems and plantations (Schmitt, 2006).Belete forest in Jimma zone was cleared to establish coffee plantations during the past decades (Cheng et al., 1998).On the other hand, communities like Apodytes dimidiata -Clausema anisata, where Apodytes dimidiata has been reported to occur in forest clearings/edges and described by other authors as having characteristics typical of early successional species (Schmitt, 2006) this may be because of the highway road to Bonga which divided the forest in to two and clearing of the forest for the electric power extension.While Pouteria adolf-friedicii is an emergent climax tree species within the Pouteria adolf-friedicii -Dracaena afromontana community, which is characteristic tree of moist evergreen montane forest.
The proportion of medium-sized individuals is larger than the large sized individuals (DBH > 20 cm) but the ratio is relatively lower than the results obtained for other forests Menagesha Suba and Chilimo forests (Tamrat Bekele, 1993), Masha Anderacha forest (Kumlachew Yeshitela and Tamrat Bekele, 2003) and Menna angetu forest (Ermias Lulekal et al., 2008).The proportion of small-sized individual was much larger (40.33%) although the above ratio is lower, indicating that BMEMF is at good regeneration.
The general trend of population structure showed an inverted J-shape for DBH classes.The majority of the species had a large number in smaller-diameter size classes with decreasing frequency as the size class increased.If a particular tree species displays such a size distribution, then continuous recruitment can generally be inferred, suggesting that the population is viable as sufficient regeneration it taking place for the population to be maintained (Newton, 2007).Even though the overall DBH distribution revealed inverse-J shape, different population dynamics for different species were revealed.According to Midgleya and Niklas (2004) the mean total basal area of tropical forests is 35m 2 ha -1 .Therefore, the total basal area of BMEMF when compared to tropical forest was found to be very high.Even though about 44.85% of all the individuals had DBH less than 9.5 cm (DBH class 1), the percentage contribution of these classes to the total Kflay, G and Kitessa, H (MEJS) Volume 6( 1 Forest regeneration requires the establishment of seedlings and saplings within the same (similar) environment where the parent trees grow.However, in rain forests, environmental conditions determining performance of adult trees contrast with those under which their seeds germinate and develop.Adult trees occupy a volume of the forest canopy, with levels of light availability at least one order of magnitude higher than those prevalent in the forest understory (Pugnaire and Valladares, 2007).Regeneration status of the forest was analyzed by comparing saplings and seedlings with the matured trees according to Dhaulkhandi et al. (2008) andTiwari et al. (2010).
The present study showed that regeneration of BMEMF is at good status (Fig 5).
Even though the regeneration status of the forest is good, it has been observed that there were few tree species which are either regenerating poorly (example; Hagenia abyssinica and Fagaropsis angolensis) or not regenerating at all (example; Spathoda campanulata).Moreover, regeneration status of Podocarpus falcatus is restricted only to two quadrats only which were nearest to the mature Podocarpus falcatus trees.This may be due to habitat restricted preferences and seed predators (Mwavu and Witkowski, 2009).Belete Moist Evergreen Montane Forest shared significant number of species with Yayu, Gura ferda, Mana angetu, and Sheko forests in decreasing order.The high similarity observed among these forests could be due to similar climatic conditions.

CONCLUSION AND RECOMMENDATION
Belete moist evergreen montane forest is one of the National Forest Priority Areas (NFPAs) Ethiopia which comprises economically and ecologically important plants.The edge of the forest, which is easily accessible by the people of the community, is planted by coffee.This is disturbing and reducing the size of the forest.The major threats observed in Belete forest were encroachment, coffee production and agricultural expansion.Thus proper management and monitoring practices is required.Hence the following recommendations are forwarded.
-Species with low Important Value Index should be given appropriate attention and should be conserved in-situ through the collaboration of local communities and the District Agriculture and Rural Development Office, NGOs and other stakeholders.
-Continuous forest inventory should be conducted.
-Planning and management of the forest should be assisted by research findings, such as detailed ecological studies in relation to various environmental factors such as soil type and properties to promote the sustainable use of the forest and its products -Comprehensive studies should be initiated to document the plant resource utilization pattern.

ACKNOWLEDGMENTS
We are grateful to the Jimma University for provision of financial support to conduct this research.The staff members of the National Herbarium, Ethiopia are also greatly acknowledged.

Cheng
valley to the top of the ridge.Sample quadrats 20m x 20 m (Trees), 5m x 5m (Seedlings, Saplings and Shrubs; and Lianas), and 1m x 1m (Herbaceous layer) were laid down (smaller quadrats within the larger quadrats).The sample quadrats were laid down along transects at a distance of 50m from each other using measuring tape meter.A total of 69 quadrats (2.76 hectare) were sampled.Individuals were classified in a series of girth classes at specific intervals (≥10 cm Diameter at Breast Height (DBH) (considered as trees) 3.5 to 10 cm DBH) (saplings) and DBH less than 3.5 cm (seedlings) according to Dhaulkhandi et al. (2008); and Tiwari et al. (2010).
The nomenclature of the Species followed the published volumes of the Flora of Ethiopia and Eritrea (FEE).
inverted J-shape (Olea capensis); the density of individuals in the lower DBH class (especially 1 and 2) is very high but becoming lower in the highest DBH classes even nothing in some DBH classes like (6,7 and 8).This showed that there is selective cutting of the species for different purposes like for construction and fuel wood.
only 6.2%.Conversely, individuals in the DBH classes greater than 40 cm had a density of about 19.56% of the total, but they contributed to about 71% of the total basal area computed for the Forest.The high IVI value of the species is mainly due to their high dominance and density which may be due to their low demand by the local people for timber (Example Syzygium guineense, Ficus sycomorus and Schefflera abyssinica) and other construction material; and their high value for honey production (Schefflera abyssinica, Pouteria adolfi-friederici and Croton macrostachyus).Distribution of species among different IVI classes indicated that most of the species were in the lower IVI classes.The most important ten species contributed about 67.29 % of the total importance values.

Table 2 .
Phyto-geographical Comparison of BMEMF with other forests in Ethiopia; N= Number of species included in comparison, a= common to both forests, b= found only in BMEMF, c= found only in the forest in comparison with BMEMF, and S = Sorensen`s similarity coefficient.