Plant Species Composition and Conservation Values at Dilla University Botanical and Ecotourism Garden, Dilla, Ethiopia

Ethiopia has a diverse topography with higher plant species composition and estimated to the higher proportion of endemic plant species. Currently, several factors drive natural forest destruction in the country, extensive agricultural land expansion triggered by increasing human population is probably the dominant force. Te Dilla University Botanical and Ecotourism Garden was established targeting to rescue threatened fora from extinction, contribute towards conservation, and research on biodiversity and sustainable education as well as ecotourism development. Te study was aimed to generate basic scientifc information by identifying and documenting the formerly available plant species in to the garden and provide information for farther plant collection planning and research. Systematic sampling method was used to collect the vegetation data from 52 plots of 20m × 20m (400 m 2 ) quadrats. To collect data for herbaceous plants, fve 1m × 1m subplots were laid in each of the main plot, where four were at the corners and one at the centre. Vegetation classifcation was performed using R-programme version 3.6.1 software packages. Shannon–Wiener Diversity Index was used to calculate species diversity, richness, and evenness. A total of 408 plant species, including trees (30%), shrubs (25%), herb (30%), grass (6%), and 9% of other species, were collected. Te identifed species belong to 287 genera and 105 families. Out of this, 27 species of plants are endemic to Ethiopia and 72 plant species were screened as a medicinal plant used for the treatment of human diseases. Based on IUCN Red Data List, among the endemic plant species nineteen species were least concern; two were near threatened; two were endangered while four were vulnerable. Tree vegetation community types were identifed from the hierarchical clustering analysis. Te result designates that Dilla University Botanical and Ecotourism Garden has high plant species composition and diversity with a good distribution. Te higher composition of this ecologically, economically, and socially important plant species at its early stage makes the garden a unique garden in the country and realize to be a centre for research, education, and tourist destination.


Introduction
Ethiopia has a diverse topography with higher plant species composition, where 6,000-7,000 species of higher plants exist in the country of which about 780-840 (12-13%) plant species are estimated to be endemic [1,2].However, these biologically rich resources of Ethiopia are vanishing at an alarming rate due to monocropping and expansions of road construction through vegetation are becoming other causes of deforestation.Currently, increasing rate of drought, desertifcation, and shortage of food for both humans and animals are becoming serious problems that need attentions [3].Although several factors drive natural forest destruction in Ethiopia, extensive agricultural land expansion triggered by increasing human population is probably the dominant force [4,5].Te indigenous agroforestry systems in the southeastern Rift Valley escarpment of Ethiopia were shown to maintain a high proportion of native tree species (86%).Tis is considerably higher than reported for traditional treecrop and Enset-cofee agroforestry systems in the eastern and southern parts of Ethiopia [6][7][8].
Today the forest cover in Ethiopia is less than 3% compared with an average of 20% for sub-Saharan Africa [9].Te need for fuel wood, Forest conversion to farmland, seasonally set forest fres, and over grazing areas have been indicated as the main causes of forest degradation; frequently leading to loss of forest cover and biodiversity, erosion, desertifcation, and reduced water resources [10].
Te destruction of vegetation and environmental degradation has become issues of national and global concern in recent years.Tis is because of the fact that declining vegetation cover and depletion of natural resources are closely associated with drought and food shortages that have become major threat afecting the life of millions of people.Te depletion of the natural vegetation in many parts of the country has also led to the threat and decline in number and distribution of many plant species [11].
According to Kelbessa et al. [12], 120 threatened endemic plant species are known from Ethiopia.Tirty-fve of these species were from the Dry Afromontane forests of the country.Terefore, there is a need to conserve the natural vegetation.Tis could be achieved by appropriate management and use plans that include ecologically sound restoration or rehabilitation measures.Tere are diverse approaches and techniques to restore land and vegetation.Maintaining the Floristic composition, natural regeneration species, and conservation of the forest are among the approaches which closely linked with low cost in the form of in-situ conservation system.
Tus, establishing Botanic Gardens have signifcant role to save plant resources of special value from the looming destruction and eventual extinction.Botanic Gardens play major roles in strengthening conservation and care for plant species, particularly rare, economically important, and endangered species under threat by natural and manmade factors, including ex-situ conservation and appropriate scientifc protection and care.It is accepted worldwide that Botanic Gardens are institutions working on conservation, care and research, and education services.Moreover, it also provides ecotourism services of natural attractions and aesthetic value from fower, seedling shops, and restaurant services.
Botanic gardens are delineated as a living museum that holds individual specimens or collections of plants for scientifc, educative, conservation and aesthetic purposes.So that it defned, "Botanic gardens are institutions holding documented collections of living plants for the purposes of scientifc research, conservation, display, and education."[13].Te botanic gardens have worked to prioritise the plants facing threat, take conservation action both in situ and ex situ, tackle overexploitation of individual species, inform and educate visitors and the wider public, and champion plants.Te recently established Dilla University Botanical and Ecotourism Garden is located in southern part of Ethiopia, Gedeo zone, which is located on the escarpments of the south eastern Ethiopian highlands overlooking the Rift Valley.Te site has geographical, archaeological, biological, cultural, and political values.Geographically, the site has diferent types of rocks and very attractive landscape, archeologically it has diferent engravings and cave, and biologically it is rich both in plants and animals biodiversity.So, the signifcance of the garden for conservation of Ethiopian biodiversity especially for low land and mid land plant biodiversity is unquestionable.Te aim of this study was to generate basic scientifc information on plants by identifying and documenting the formerly available and introduced plant species and vegetation structures of the garden.It will be important for the future plant collection planning for conservation, research, and education activities.

Methods
2.1.Site Descriptions.Dilla University Botanical and Ecotourism Garden (DUBEG) is the conservation initiative established since 2017 G.C. on 130 hectares in Gedeo zone at the west corner of Dilla town, Sesa sub-City, Odaya Kebele between main and Odaya campus of Dilla University.Te vision of the garden is to achieve internationally renowned botanic garden, witnessing Ethiopia's foral richness and its centre of origin for many economic plants.Te mission of the garden is to rescue threatened fora from extinction, contribute towards conservation, and research on biodiversity and sustainable education as well as ecotourism development.Te geographical co-ordinates of the garden lies between latitude 6 °25′55.66″N and 6 °26′ 44.6″N and longitudes 38 °16′05.12″E and 38 °17′25.56″E (Figure 1).Te garden is located 1 km northeast of Dilla town and 1.5 km north to Dilla University main campus.Te site is bordering with Laga Dara River (Sidama zone) to North, Don Bosco pig production to South, Mejege River (Abaya woreda) to Weast and Saron log and Odaya campus of Dilla University to East.
Te site has geographical, archaeological, biological, cultural, and political values.Geographically, the site has diferent type of rocks and very attractive landscape, archeologically it has diferent engravings and cave, and biologically it is rich both in plants and animals biodiversity.Culturally, the local people were using the site for diferent ceremony like wedding and diferent concerts.Politically the site is also the borderline of three administrates zones (Gujje, Geodo, and Sidama).Terefore, the area gives great opportunity to strengthen the relationship between the three zones with Dilla University, the university with other stakeholders.
In addition, DUBEG is a potential area for education, conservation, research, and recreation.It also has an access for infrastructure, water (3 rivers), road, relatively fertile soil, geographically it is attractive (ranging from sheltered gullies and streams, rivers, valley, gorge, caves, escarpment, to steep hillsides, and exposed hilltops), and it is near to the Dilla university.Other than these the area has rich source of indigenous crops, wild animals, cultural heritages (engravings of wild animals expected to the age of antiquity), and cave.
Te garden activities have currently started on land about 20.7 hectares at the subsite locally called Waleme.Don Bosco Catholic Church protected this area for the last 30 years.At this site, the garden has two separate parts nursery site (2.6 hectares) and the main garden (18.1 hectare).Te internal parts of the main garden also have diferent components, which are uses for various 2 International Journal of Forestry Research activities of the garden.Each of the garden components has a particular function.It has seven main components, such as Child Garden, Scientifc Garden, Recreation site, Nursery site, Science Cafe, research and staf ofce, and Infrastructure which includes roads, irrigation system, store room, composite site, and compound (fence).Te nature of these diferent components determines the primary opportunities for teaching and visiting.) quadrats laid at every 50 meters along seven transect lines from south-north direction using compass.Te distance between each transect line was 70 m laid in a zigzag form of starting point of laying plot.To collect data for herbaceous plants, fve 1 m × 1 m subplots were laid in each of the main plot, where four were at the corners and one at the center.Plant species in each plot was counted and recorded at individual level; voucher specimens were collected, numbered, and pressed for further identifcation by using checklists and fora Ethiopia and Eretria [14].Additional plant species occurring outside the quadrats, but inside the forest within 10 m distance, were also recorded only as "present" for foristic composition, but they were not used in the subsequent vegetation data analysis [15,16].Te vernacular (local) names were used when available.Finally, socioeconomically important plant species and their status were screened based on the previous literatures.using the Shannon-Wiener index (H′) and Simpson's dominance index (1-D) [17].

Floristic Composition.
A total of 408 specimens of plants (herbs, shrubs, trees, shrubs/trees, climbers, and tree/ climbers) were identifed and documented from Dilla University Botanical and Ecotourism Garden.Oof them, 131 were introduced from a diferent area for the purposes of conservation and garden beautfcation.Tree species, Ziziphus spina-christi, Ilex mitis, Eucalyptus citriodora, and Opuntia fcus indica, and some annual plant species were collected outside the sampling plots for the purpose of documentation of available plant species.Tose plant species was not incorporated in statistical data analysis.Te collected species were composed of 32% trees, 32% herbs, 24% shrubs, 4% grass, 4% climbers, 1% liana, and 1% Fern and Epiphytes species (Figure 3).Te identifed species belong to 287 genera and 105 families.Te major families were Fabaceae represented by 44 species (10.81%),Poaceae and Euphorbiaceae each with 22 species (5.41% each), Asteraceae by 20 species (4.91%), and the remaining (48%) families were represented by one species (Table 1).

Plant Community Classifcation.
Te abundance data of a species were used for the analysis.R program Version 4.2.2 software (Vegan and labdsv package) was used to perform a hierarchical cluster dendrogram, which depicted the vegetation community of plant species.Tree communities (clusters) were identifed as a result of grouping of quadrates and designated as communities 1, 2, and 3 shown in the dendrogram (Figure 4).
Te results of Sorensen's Similarity Index indicate the vegetative community similarity in species composition is slightly varied among communities.Te highest similarity was observed between communities II and I (27.7%).Te least similarity was observed between community II and III (18.1%) and relatively shares less species within the community.Overall similarity coefcient ranges from 18 to 28% among all the communities.Tus, species composition dissimilarities account for 72% for the most similar communities and 82% for those that share least similarity (community II and III).
Generally, the clusters represent the actual DUBEG components, community number one represents the nursery site and the protected forests along the river, community number two represents scientifc garden and child garden sites, community number three represents recreation site and science cafe.

Species Diversity.
Te Shannon-wiener index (H) for the communities refect the deference in their species richness and evenness.Species diversity among the Community types is categorised from highest to lowest as Community-II > Community-I > Community-III and species evenness Community-II > Community-I > Community-III has the highest species richness and highest H'max.Community III has the least even distribution, the least diversity, the least species richness, and the least equitability.Generally, the three communities have almost the same species distribution (equitability or evenness) but comparatively community III has the least species evenness (Table 2).
Following a desk study to review the literature on ethnobotanical uses of plants, it was found that 72 plant species belonging to 38 families were screened as a medicinal plant used for the treatment of human diseases (Table 4).Accordingly, the life forms of medicinal plants reviewed belongs to 28 trees (38.89%), 17 shrubs (23.61),21 herbs (29.17%), two climbers (3.81%), two liana (2.78%), and one grass (1.39%).As the referenced authers indicated, the traditional healers have harvested these medicinal plant leaves, roots, barks, seeds, fruits, stems, fowers, barks, seeds, or latex for treatment of human diseases.
For the documentation purpose, 408 plant species are listed by their botanical name following the Flora of Ethiopia and Eritrea Volume 1-8 and Natural Database for Africa (NDA).On CD-ROM Version 2 (Table 5).Te higher plant species composition at its early stage rank Dilla University Botanical and Ecotourism Garden at the second level among the botanic garden (Gullale botanic garden) and other protected feld Gen banks and make it a unique garden to the country.4 International Journal of Forestry Research  [24] Red Data List, 19 species were least concern, two were near threatened, and two were endangered, while four were vulnerable.Overall diversity and evenness were 1.79 and 0.09, respectively.According to Kent M. et al. [25], the Shannon-Weiner diversity index normally varies between 1.5 and 3.5 and rarely exceeds 4.5.In our study area, however, there is high diversity and evenness showing more or less even representation of individuals of most plant species in the sampled quadrats.Vegetation classifcation is a powerful tool employed for several purposes, including efcient communication, data reduction, and synthesis, interpretation, and land management and planning.It also provides one way of summarizing our knowledge of vegetation patterns [26].Hence, three plant community types were identifed at the Dilla University Botanical and Ecotourism Garden.Tese three communities also represents the actual garden Community number three represents the scientifc garden and child garden areas of the garden.Tis area is where high plant collection and plantation have been engaged.Tat is why this community was represented only by two plots.Species richness (number of species) was determined by summing up the number of species identifed [27].Te diversity index [28] was computed for the three communities from the study garden.Te diferent values of H′ for the communities refect the diference in their species richness and evenness.Te minimum value of H′ is zero, which a value for a community with a single species and increases as species richness and evenness increases.Te variation in species richness and diversity may be attributed to varation in altitude, latitude, and soil gradient and disturbance factors [29].Te relatively higher similarities between community types IV and I is probably due to the similar environmental conditions and their similar altitudinal range.

International Journal of Forestry Research
As reported by Dereje D. et al. [30], in addition to altitudinal gradient, other environmental factors such as aspect, slope, and soil physical and chemical properties have sound efects on patterns of vegetation in communities.Te study conducted in a similar method at diferent areas of catchiment indicates 213 plant species were collected from Chilimo forest [31] and 80 woody species from Gamo Gofa Zone [32].Although, a total of 155 socioeconomical important plant species were collected from natural forest and 65 plant species from home garden at Gedeo Zone, Wonago Woreda [33].Comparatively, DUBEG is composed of higher ecologically and socioculturally important plant species.Te accessible plantation of collected plant species from various areas for the purpose of conservation, research, and education in DUBEG at the site of scientifc garden and child garden has a great role for the existed variation among the communities.Te existence of higher plant species on these selected areas is also very important to make plant conservation awareness, education, and demonstration for peoples visiting the site.It is also important to enhance and increase awareness of cultural diversity as part of the conservation mission [34].Allium sativum L.
Tree Haemorrhage [18] 10 International Journal of Forestry Research

Figure 3 :
Figure 3: Proportion of life form of plant species collected from DUBEG.
Te computer R-programme version 3.6.1 Vegan package was used to analyze the vegetation data through Agglomerative Hierarchical Classifcation technique.Te Euclidean distance and Ward's method were used for clustering the vegetation data.Its classifcation was made using cover abundance values as class labels.Te clusters were assigned in number to indicate the individual communities' number.

Table 1 :
Te number of families, genera, and species of plants in DUBEG (RF � relative frequency).
have a medicinal value that is used for the treatment of human diseases.According to IUCN

Table 2 :
Species richness, evenness, and Shannon-Wiener diversity index of the plant community types.
DissimilarityFigure 4: Dendrogram showing the plant community types of DUBEG.

Table 3 :
List of endemic species of DUBEG, their habit, and IUCN red list categories.

Table 4 :
Ethnobotanical uses of plants collected from DUBEG that used for the treatment of human diseases.

Table 5 :
List of plant species collected from Dilla University Botanical and Ecotourism Garden.