Medicinal Plant Composition, Distribution, Usage and Conservation Status in Nole Kaba District, West Wollega, West Ethiopia

Background Methods Data were gathered through semi-structured interviews, group discussions, and eld observations. The analysis employed descriptive statistics and quantitative indices including Factor of Informant Consensus (Fic), Fidelity Level (FL), and Sorenson’s Similarity.


Background
Ancient medical manuscripts written by Ethiopian churchmen and Muslim scholars revealed that medicinal plants have long been playing an important role in human healthcare in Ethiopia [1]. The knowledge and skills associated with the use of medicinal plants have been passed on orally to their family members by healers, knowledgeable elders, religious leaders, and other members of the clergy for most of the centuries [2]. In addition to renowned traditional healers, many Ethiopians have practiced and still practice home-based medications using various herbs such as ginger, garlic, and eucalyptus leaves to treat health problems such as colds, fevers, and headaches. Although current estimates are lacking, previous estimates indicate that the use of plant-based traditional medicine meets up to 70% of human health needs in Ethiopia and understandably the proportion that goes to traditional herbal medicine use is a little less than this gure. Regarding medicinal plant richness, the ora of Ethiopia comprises over 1500 medicinal plants (Ongoing review) which are used by ethnic communities in different parts of the country. Most of these medicinal plants are harvested from the wild, while few are cultivated/or grown as crops in homegardens and farmlands.
Despite the richness, the natural vegetation and associated medicinal plants are declining in area coverage and species abundance in many parts of the country, including the present study area. Remnant tree/shrub stands in farmland and many parts of the study area are a testimony to vegetation shrinkage or deterioration.
Assessments of threatened plant species by [3] found an increasing number of threatened plants over the years. Among these, Echinops ellenbeckii and Taverneia abyssinica are endangered and critically endangered, respectively. Equally, species such as Echinops kebericho and Securidaca longepedunculata are highly declined and endangered in the wild due to overexploitation and habitat destruction. The latter two species did not appear on the IUCN RED List of threatened species yet. However, eld observations clearly show that these species are becoming rare in most parts of Ethiopia due to unsustainable use and other pressures. The decline of such medicinal plants is inevitably leads to the erosion and/ or loss of ethnomedicinal knowledge and this consequently is an important public health concern. Given growing pressures on medicinal plant diversity and associated knowledge, ethnobotanical documentation and identi cation of potentially useful and threatened species are essential for development and conservation planning. This study was, therefore, aimed to identify medicinal plants and their distribution; assess the health problems, analyze medicinal plants usage consensus, and identify threats to medicinal plants. The ndings of this study are believed to contribute to the conservation and sustainable use of medicinal plants; and enrichment of the Flora database of the National Herbarium.

Materials And Methods
The study area, Nole Kaba District is geographically located in west Ethiopia between 8 0 39′45′′N and 8 0 58′10′′N latitude and 35 0 34′41′′ E and 35 0 58′49′′ E longitude in west Wollega, Oromia Region, at about 491 km west of Addis Ababa (Figure1). According to the 2007 national census report, the total human population of Nole Kaba District is 60,793, consisting of 29,667 men and 31,126 women, largely (97%) belonging to the Oromo ethnic group. The people have settled in different agroecological settings namely, highland (above 2100 m asl.), midland (1900-2100 m asl.), and lowland (1500 -1900 m asl.) which show variations in temperature. According to the rainfall and temperature data collected by the National Meteorological Service Agency for the years between , the mean monthly temperature is 21.4ºC with mean minimum and maximum monthly temperatures of 14.3ºC and 30.5ºC, respectively. The mean annual rainfall is 1610 mm with a unimodal distribution. The soils are well drained, strong to moderately acidic, deep, and reddish-brown in color. The natural vegetation towards the higher altitudes (>1900 m asl.) belongs to moist Afromontane forests while those towards the lower (<1500 m asl.) altitudes belong to Combretum-Terminalia woodlands.

Selection of study sites and informants
The study areas were strati ed into three agroecological settings namely, highland, midland, and lowland. These agroecological settings have somehow varied in temperatures, altitudes, and vegetation assemblages. Within each agroecological setting, representative study sites were identi ed proportionally based on area coverage/proportion of the agroecological zones in the study district. Accordingly, six from midland, four from highland, and two from lowland agroecological zones were selected. Informants were sampled randomly at each village following [4]. However, traditional healers were sampled purposively. The sample size was determined following [5] from 11,386 households. Overall, 371 informants (197 men and 174 women) aged between 13-90 years were involved in the interviews. In the course of interviews, 12 more knowledgeable informants (8 men and 4 women) were considered as key informants for group discussions. The research obtained formal research permit from Addis Ababa University, Ethiopian Biodiversity Institute and the local administration of the study area. Each informant gave oral informed consent prior to data collection.

Data collection and analysis
Data was gathered using semi-structured interviews, group discussions, and eld observations. Herbarium specimens of all recorded medicinal plants were collected, pressed, dried, and identi ed by using Ethiopian Flora Books and by cross-checking with authenticated herbarium specimens at National Herbarium, Addis Ababa University.
The data were analyzed using both descriptive and inferential statistics. Furthermore, the following indices were employed to analyze the quantitative data. Factor of Informant Consensus (Fic) adopted by [6] was employed to see the degree of agree ment among informants interviewed concerning the use of plant species within a given ailment category.
Where, n ur is the number of use reports for a particular disease category and n t is the number of different plants (taxa) that are reported to treat this disease category.
Fidelity Level (FL) was computed following [7] to estimate the relative importance of medicinal plants reported for treating particular disease categories.
Where Ip = number of informants that use a species for principal disease; Iu = total number of informants that cited the species to treat any other disease. Sorensen's (Ss) similarity index was computed using R software version 3.41 [8] to determine medicinal plants similarity between different study sites. Furthermore, pairwise comparison was conducted to prioritize factors threatening medicinal plants [4]. The number of pairs for pairwise comparison was determined using N (N-1)/2 relationships, where N is the number of threat factors.

Medicinal plants composition and distribution
The study found a total of 162 medicinal plant species belonging to 65 families and 135 genera. Of the total, 43.8% were reported only for human health problems, 35. The medicinal plants were distributed across seven habitat types which were classi ed based on land use (farmland/border, homegardens, pasture lands, roadsides) and physiognomy of the vegetation (forest, woodland, riverine vegetation). The habitats harboring high proportion of medicinal plants were forests (34%), followed by farmlands/borders (33%), roadsides (10%) and homegardens (9%) (Figure 3). Some medicinal plants were distributed across more than one habitat some others were restricted to a particular habitat type. Species such as Ageratum conyzoides, Bersama abyssinica, Croton macrostachyus, Justicia schimperiana and Salvia nilotica were distributed across multiple habitat types while others con ned to habitat characterized by Comberetum-Terminalia woodland (e.g Capparis tomentosa, Combretum molle, Echinops amplexicaulis, Hymenodictyon oribundum, Securidaca longepedunculata, Stereospermum kunthianum, Warburgia ugandensis, and Ximenia americana) and moist Afromontane vegetation (e.g Adiantum poiretii, Chionanthus mildbraedii, Cyperus scherianus, Galiniera saxifraga, Pavetta oliveriana, and Vepris dainellii). In terms of altitudinal distributions, the occurrence of many medicinal plants was between 2000-2200 m asl. This altitudinal range is characterized by a moist and warm climate, which also includes Jorgo Wato Forest (JWF).

Medicinal plants similarity
The number of medicinal plants reported in the sampled study sites varied between 46 and 75 species. Many of the medicinal plants were shared and used commonly in these sites. The highest similarity (Ss = 0.70) was observed between Siba Silase and Hrbu Abagada, while the least (Ss = 0.31) was observed between Shimala Illu and Aydobi (Table 1). The highest medicinal plant similarity value suggests more number of shared medicinal plants and associated knowledge. The sites that shared a greater number of medicinal plants are geographically located closer to each other and found within the same agroecological settings. These sites are bordered by JWF, which was the source of many medicinal plants reported in this study. This nding suggested that there is an intra-cultural exchange of medicinal plant knowledge between these sites. On the other hand, the low medicinal plants use similarity between some sites may be due to variation in environmental settings (relief, climate, and altitude), which may in uence the availability and utility of medicinal plants. It may also be due to less opportunity for exchange of ethmomedicinal knowledge which in turn due to greater distance between the sites. Medicinal plants shared commonly across most study sites were Brucea antidysentrica, Capparis tomentosa, Croton macrostachyus, Datura stramonium, Dracaena steudneri, Drymaria cordata, Justicia schimperiana, Ocimum lamiifolium, and O. urticifolium. The use of these species over wider localities may be due to their adaptability to and availability in broader altitudinal and habitat ranges.  The study documented with a total of 45 human and 31 animal health problems. In both human and animal cases, the health problems are grouped into eleven major categories based on affected organs or features of the health problems. The human health problem categories are general malaise, dermatological, auricular, dental, neck and optical, antidote, liver and kidney, reproductive, respiratory, burning in the chest, and thoracic problems.
Most of these categories are also considered in grouping animal health problems. Of the animal health problems, 18 (58 %) were affecting cattle, while the remaining 13 (42%) were affecting sheep, equines, and dogs.
In the case of humans, the factor of informant consensus analysis revealed the highest values for treatment of bone fracture (Fic = 1.00) and stomachache (Fic = 0.94) ( Table 2). The study found that multiple plants were reported for the treatment of a single health problem. The health problems treated with the highest number of medicinal plants were toothache (20 species), followed by rabies (18 species), migraine (16 species), and febrile (15 species). The study also found multiple therapeutic uses of a single medicinal plant. Among these, Echinops longisetus was reported to have eight different therapeutic uses, while Croton macrostachyus and Capparis tomentosa reported having seven therapeutic uses each (Table 2).  (Table 3).  Fidelity level analysis of ethnoveterinary plants revealed the highest delity value of Buddleja polystachya (FL = 100%) for a treatment eye problem and Pentas schimperiana (FL = 100%) for bone fracture (Table 5). Dosage forms and application of remedies Herbal remedies were prepared from fresh (64%), fresh or dried (34%), and dried (2%) plant materials for humans. For animals, 62% of the remedies were prepared from fresh, while 38% were from either fresh or dried materials.
Informants thought that fresh plant materials were more effective in healing than dried materials. In many cases, dried remedies are applied as smoke and or fumigant. Scarce medicinal plants that may not be locally available are often dried and preserved for future use. The majority (87%) of human remedies were prepared from single species or plant parts. In several instances, more than one plant part of the same species was used in the preparation of various remedies. Drinking (44%) was the most common method of applying the treatments, followed by crushing/smashing and inhaling or adding drops (14%). Smoke inhalation and steam bath were the least reported applications (Figure 4).
The main ingredient used along with or added to remedies was salt, followed by butter, coffee, milk, honey, garlic, and ginger. Other ingredients like barley soup/gruel, sugar, pancake, lemon, yogurt, hot pepper, vaseline, sugar cane, and ash were used rarely for the preparation of remedies.

Factors affecting the availability of medicinal plants and management status
Analysis of threat factors identi ed ve principal factors responsible for the declining availability or scarcity of medicinal plants, namely agricultural expansion, deforestation, overharvesting, overgrazing, and drought/climate change. Pairwise comparison prioritized the rst two factors as top factors that have contributed to the declining availability and loss of medicinal plants (Table 6). These factors have together altered the habitats of many wild plants, including that of medicinal species.

Composition and distribution of medicinal plants
The ora of the study area is rich in medicinal plants that are used for the treatment of a wide range of human and animal health problems. The families shown to be richest in medicinal plant species are Asteraceae, Fabaceae, Solanacceae, and Lamiaceae, which are also among the dominant owering plant families in Ethiopia [9] and in the world [10]. Furthermore, these families are known to constitute secondary metabolites like essential oils, antibacterial, and antifungal products [11]. This result suggests that families represented by the highest number of medicinal plants can be considered as a target group in the search of/bioprospecting of drug compounds. The composition of medicinal plants includes endemic species among which, Echinops longisetus, Lippia adoensis, and Solanecio gigas are reported on IUCN Red List as threatened species [3]. In terms of habitat distribution, a large proportion of medicinal plants were distributed in the forest, followed by farmland/borders and roadsides. The high species diversity in forests is possibly due to structural complexity, heterogeneous niche, micro-habitats created by trees, bushes, and variable topographic locations where forests occur, and often forests get some level of protection from anthropogenic factors. This is in agreement with previous studies [12] who reported that tropical forests are home to a large number of medicinal plants, most of which remain undiscovered. Similarly, the high medicinal plant diversity in farmland/borders may be attributed to human activities, which could favor the dispersal of propagule, especially of weedy and herbaceous medicinal plants. This observation agrees with [13], who found many medicinal plants in farmlands. Thus, the ndings suggest that habitats such as forest/forest margins and farmlands/farm borders could be target areas during the collection of medicinal plants germ-plasms for ex-situ conservation. Regarding species distribution, the results showed that many medicinal plants distributed in more than one habitat type. Wider habitat distribution of species could increase the availability and accessibility of the species for public use. From a conservation point of view, however, species found in different habitats are under less harvesting pressure compared to those that are locally restricted.

Medicinal plants growth forms and parts
The results showed that the growth forms of the documented medicinal plants were predominantly composed of herbs and shrubs. These could possibly be due to the fact that herbaceous plants are available in many habitats, including agricultural elds. It is expected that the more accessible a plant taxon is in an area, the more the likelihood of being used by or interacting with local people [14]. In addition, ease of harvest may also contribute to the preference and predominant use of herbs in traditional medicine.
Regarding medicinal plant parts, leaves and roots were the most commonly used for the preparation of the remedies. Several medicinal plants or parts are sometimes used for the same medicinal purposes. In such a case, users may choose the most readily available, easily harvestable, and applicable parts. These may contribute to the increased use of a particular part. For example, the most frequent use of parts such as leaves may be related to ease of harvesting, preparation, and application as well as their e cacy because, particularly actively growing young leaves are accumulation centers of secondary metabolites known to contain higher amounts of healing compounds. [15] argued that the most frequent use of a plant or a plant part might rather suggest that this plant or plant part is not toxic to human health.
In view of conservation, the most frequent use of roots is a concern because it is considered to be destructive; it could threaten and endangered species' survival. Species such as Echinops longisetus, Securidaca longepedunculata, and Warburgia ugandensis were harvested for their roots in the present study area and have become vulnerable to extinction locally. Echinops longisetus is already reported in IUCN Red List of threatened species under Least Concerned (LC) threat category [3] but locally threatened as seen in the present study area. Although further assessment and evaluations are required, Securidaca longepedunculata and Warburgia ugandensis are under threat and need conservation attention.

Informant consensus and applications of medicinal plant remedies
The results revealed that medicinal plants are used by the majority of the rural people even today. The medicinal plants documented in this study were reported to treat a wide range of health problems. Among the human health problems, bone fracture, wound, rabies, febrile, migraine, stomachache, and toothache showed high informant consensus values. Bone fracture, eye problem, rabies, and babesiosis were among animal health problems that showed a high factor of informant consensus. High informant consensus values may indicate a more prevalence of these health problems in the area. A high informant consensus value may also indicate more agreement among informants on the medicinal plants reported for treatments of health problems. Some of the health problems are treated by different medicinal plants. The use of different plants for the same application might increase treatment options and contributes to healthcare security. For example, when a particular plant is not available due to various reasons such as seasonality or inaccessibility, alternative species could be used as a remedy. The presence of alternative remedies might also reduce harvesting pressure, particularly on rare medicinal plants.
High informant consensus may also imply more shared knowledge on the reported medicinal plants. Most of the medicinal plants that showed high informant consensus have been used as remedies in other parts of Ethiopia. For example, Phytolacca dodecandra has long been used in Ethiopia for numerous ailments; anti helminths, eczema, gonorrhea, abortion, malaria, rabies, skin disease, gonorrhea, and liver disease [1,16]. Brucea antidysenterica was reported for the treatment of cancer, diarrhea, evil eye, leishmaniasis, rabies, wound, skin disease, dysentery, hemorrhoids, weight loss, fever, and diarrhea [1,17]. Another most frequently used species was Embelia schimperi, which was reported for the treatment of tapeworms and roundworms for gastrointestinal complaints [13]. In line with this, [6] suggested that medicinal plants with high informant consensus values can be considered as culturally signi cant species.
Furthermore, many of the medicinal plants documented in this study, including those that showed high informant consensus values, were found to possess phytochemical and pharmacological properties. For example, phytochemical screening of plant parts of Stereospermum kunthianum con rmed the presence of avonoids, tannins, saponins, terpenoids, glycosides, sterols, coumarins, quinones, and higher fatty acids [18]. These phytochemical compounds provide various therapeutic properties [15]. Phytochemical screening of leaf extracts of Ocimum lamiifolium con rmed the presence of tannins, sterols, avonoids, saponins, terpenoids, and alkaloids [19]. Aqueous extracts of leaves, fruits, and stems of Phytolacca dodecandra are known to contain alkaloids, steroids, phenols, triterpenoids in its leaves [19]. The berries of P. dodecandra are known to contain saponins, a compound showing molluscicidal properties [1]. A crude leaf extract of Brucea antidysenterica and Croton macrostachyus showed the presence of avonoids, saponins [17] alkaloids, phenols, triterpenoids, and steroids [20]. The phytochemicals present in these plants are known to exhibit biological activities [1,17] such as effects on the central nervous system, anti-microbial, stimulants, pain killer, anti-tumor, fungicidal, anti-helmintic activity, antioxidant, anti-viral, hepato-protective, anti-in ammatory, cardiovascular, and anti-hypertensive therapeutic effects [21].
More importantly, pharmacological evidence showed that the medicinal plants with high informant consensus in this study were reported to demonstrate pharmacological effects against harmful microbes. For example, crude extract of Buddleja polystachya leaf has shown anti-in ammatory [22], cytotoxic potentials, and anti-microbial effects [23]. Leaf extracts of Croton macrostachyus showed antibacterial activities against Staphylococcus aureus and Shigella sonnei [24]. Extracts of Ocimum lamiifolium leaves demonstrated anti-plasmodial and antibacterial effects [25]. The crude extract of Phytolacca dodecandra had shown inhibition against bacterial growth [26]; seed extracts of Brucea antidysenterica showed a signi cant effect against plasmodium parasite [25]; leaf and seed extracts of Datura stromonium revealed anti-microbial activities [27]; crude extracts of Dracaena steudneri and Capparis erythrocarpos [28] portrayed the most signi cant anti-fungal activity; extracts from Echinops longisetus leaf and stem showed strong inhibitory activity against Staphylococcus aureus; root and ower extracts showed lethal activity against earthworms and molluscicidal activity [29]. Embelia schimperi, Ocimum lamiifolium and Vernonia amygdalina were reported to possess antimicrobial effects against different microbial strains [30]. Embelin compounds found in the berries had shown lethal activity against hookworm larvae and anti-microbial effect against Staphylococcus aureus strains [31]. The crude extract of Millettia ferruginea seed and Warburgia ugandensis leaves demonstrate the stronger larvicidal effect [32]. The antibacterial, anti-plasmodial, analgesic, anti-in ammatory, anti-diarrhoeal and anti-oxidant effects of Stereospermum kunthianum extract have been experimentally demonstrated [18]. The leaf extract of Pentas schimperiana was found to exhibit anti-microbial, anti-fungal, and diabetic activities [33].

Forms of plant materials and preparation of remedies
The plant remedies were prepared mainly from fresh plant parts, while the use of dried plant parts was less common. Informants thought that medicinal plants might lose or reduce medicinal values upon drying. Indeed, such information needs further investigation to see the effect of drying on the bioactive contents of the plants.
Other studies in Ethiopia [13,34] found the use of fresh materials for most of the herbal preparations. Several factors including plants' growth stage and storage period are believed to in uence the phytochemical constituents of plants. Many unstable secondary metabolites are copiously available in fresh materials. A study by [35] revealed a higher quantity of phytochemical compounds in young plant parts than in mature parts. The same source further reported that prolonged storage of plant parts reduces their phytochemical contents and supports the use of fresh material in most traditional medicine. Thus, although further investigations on different parts of the species are needed, the use of fresh materials in the traditional herbal preparations has possible scienti c evidence. The results further showed that various ingredients, mainly salt, butter, coffee, and milk, were used together with herbal remedies. The use of these additive substances in herbal remedies could improve the healing potential, the taste, and/or avor and reduce the possible side effects of the remedies.

Factors affecting availability of medicinal plants and management efforts
In many places, the natural vegetation cover of the study area is deteriorating. Factors reported in this study are generally considered to be the principal factors for the loss of wild plant resources including those found in forests, woodlands, and pasture lands in Ethiopia [3]. Furthermore, multiple uses, over-exploitation, and destructive harvesting contributed to the decline or local loss of certain medicinal plants. For instance, Echinops longisetus and Securidaca longepedunculata are declined/or lost from the wild due to over-harvesting of roots for sale. Echinops longisetus is already reported in the IUCN Red List of threatened species [3]. These species are restricted in habitat distribution and were not available where they were previously growing, they also have a low number of individuals in their natural habitats. In many cases, slow-growing, slow-reproducing, and rare species with speci c habitat requirements are the most vulnerable group [36,37].To this end, the protection of natural vegetation favors the coexistence of different biodiversity components, maintains evolutionary processes of the species, and protects rare and threatened species [37].

Conclusions
The study found rich medicinal plant resources in the Nole Kaba District. The majority of rural people depend on these resources for the management of health problems. The medicinal species are composed largely of herbs and shrubs. Most of the plant remedies are prepared from fresh leaves and roots, which are processed in the form of infusions. Of the documented medicinal plants, Croton macrostachyus, Datura stramonium, Dracaena steudneri, Echinops longisetus, Justicia schimperiana Loxogramme abyssinica, Ocimum urticifolium, Pentas schimperiana, Phytolacca dodecandra, and Securidaca longepedunculata showed a high informant consensus and could, therefore, be considered for further evaluation of e cacy, safety, and other quality requirements of medicinal plant products. Declining or rare medicinal plants such as Echinops longisetus, Ocimum urticifolium, Pentas schimperiana, Securidaca longepedunculata, and Warburgia ugandensis should get conservation priority in protected areas (in situ), eld gene bank, and other appropriate means that are suitable to the particular species. In addition, sensitization about the need for sustainable use of medicinal plants is required to stakeholders at different administrative levels to contribute to the long-term availability of this resource.

Declarations
Ethics approval and consent to participate "Not applicable"

Availability of Data and Materials
The data supporting their ndings can be found in additional le I and 2 Competing interests 'The authors declare that they have no competing interests"

Consent for publication
Verbal consent obtained from local governments and informants

Authors' contributions
The rst authors had signi cant intellectual contribution towards the design of the study, data collection and analysis and write-up of the manuscript. The co-authors made substantial contributions to the revision and nalization of the manuscript. The authors read and approved the nal manuscript.

Funding
There is no funding/grant award