Ethnomedicinal Plant Diversity Study Around Yotyet-yewezera and Amba Natural Forest, Ezha District, Gurage Zone, Central Ethiopia

MATERIALS AND METHODS

Description of the study area: The study area is located in Ezha district, Gedeb and Yesray kebele of the Gurage zone, Southern Nations Nationalities and Peoples Regional State (SNNPRS), Ethiopia (Fig. 1). It is located in the south-west part of the country 210 km away from Addis Ababa.

Selection of informants: A total of 40 informants were selected purposively based on their medicinal plant knowledge and residence of the forests located kebeles by the recommendations of knowledgeable elders, local administers of the Kebeles and development agents exist in the communities. The informants were local inhabitants aged between 30-82 years old. Ten key informants were selected based on the indigenous knowledge and service delivery that particular informants give during an interview. Local healers qualified as key informants being traditional experts who are custodians of indigenous knowledge on medicinal plants.

Ethnomedicinal data collection techniques: Before collecting the data, official permission was secured from Wolkite University research office to the office of the district and permission was obtained from the administrator of Gedeb and Yesray Kebele. Ethnomedicinal data was collected between March 15-August 15, 2017. Ethnomedicinal investigations were carried out to collect data on medicinal plants used to treat both human and livestock disease through semi-structured interviews, group discussion and guided field observation with key informants.

Semi-structure interview: Semi-structure interviews and discussions were undertaken based on checklist of questions prepared in English and translated to ‘Guragigna’ by local translator. The individual semi-structured interview was asked information on local names of medicinal plants, parts used, methods and conditions of gathering and preparation, disease treated, dosage used, route of application, adverse effect, use other than medicinal uses, their management by indigenous people and distribution in local vegetation was collected^10,11. Eventually, the semi-structured interviews were followed by independent walks in the natural forests and homegarden, which allowed for more discussion with individual informant and the practical identification and collection of medicinal plants that was found in and around the natural forest.

Field observation: Field observations were performed with the help of field assistances on the natural forests and homegarden for practical observation on morphological features, growth form and habitats of each medicinal plant species that was existed in and around the natural forests.

Group discussion: Five key informants for group discussions from Yotyet-yewezera and Amba Natural forests, respectively with a total of 10 key informants were selected randomly from the total informants selected for ethnomedicinal data collection to gain further informations on medicinal plants at the district level.

Fig. 1:	Location of Yotyet-yewezera and Amba Natural Forest, in Gedeb Kebele, Ezha district of Gurage zone (SNNPR)

The information collected by group discussion was important to triangulate the ethnomedicinal information collected through semi-structured interviews¹⁰.

Plant specimen collection and identification: The reported medicinal plants were collected from in and around natural forests during the field walks; habits, habitat of the plants, local name, date of collection, name of collector was recorded. Preliminary identification was done at the natural habitat and the collected plant specimens were taken to the National Herbarium of Ethiopia (ETH) and medicinal plant identification were performed.

Data analysis techniques: The collected ethnomedicinal data was analyzed and summarized by using Microsoft Excel spreadsheet software. The collected data were entered into excel spreadsheet and summarized using descriptive statistical methods such as frequency and percentages. Informant consensus, preference ranking and direct matrix ranking was carried out to analyze the data.

Descriptive statistics: Descriptive statistical methods such as percentages and frequency were carried out to analyze and summarize the data on medicinal plants, use and associated knowledge. The most useful information was gathered on medicinal plants are medicinal value, application, methods of preparation, routes of administration, disease treated, parts used, habit and habitat were analyzed through descriptive statistics.

Informant Consensus Factor (ICF): The Informant Consensus Factor (ICF) was calculated for each category to identify the agreements of the informants on reported cures for the group of ailments following¹². The ICF was calculated as follows:

ICF = Nur-Nt/(Nur-1)

where, ICF is informants consensus factor, Nur is the number of individual plant use reports for a particular illness category and Nt is the total number of species used by all informants for this illness category.

Preference ranking: Five key informants were selected to assess the degree of effectiveness of five medicinal plants that treat a particular human disease by following¹⁰. The medicinal plants believed to be most effective to treat the illness was given the highest value (5) and the least effective was gotten the lowest value (1). The value of each species was summed up and the rank for each species was determined based on the total score. This was helped to indicate the most effective medicinal plants used by the community to treat the diseases.

Direct matrix ranking: Direct matrix ranking was carried out in order to compare the multipurpose medicinal plant species based on information obtained from informants¹¹. The multipurpose species were selected out of the total medicinal plants and the uses of these plants were listed and 5 randomly selected key informants were asked to assign use values to each species. Each selected key informants were asked to assign use values (5: Excellent, 4: Very good, 3: Good, 2: Less used, 1: Least used). Based on data were obtained from informants, average value of each use values for a species was taken and finally the values of each species was summed up and ranked¹¹.

RESULTS AND DISCUSSION

Medicinal plant diversity and their distribution: A total of 70 medicinal plant species used to treat human and livestock ailments were recorded in the study areas which belonged to 64 genera and 40 families. The identified plant families included: Asteraceae (7 species), Euphorbiaceae (5 species), Rosaceae, Lamiaceae and Poaceae (4 species each), Myrsinaceae, Solanaceae, Polygonaceae and Fabaceae (3 species each), Acanthaceae, Rutaceae and Cucurbitaceae (2 species each) and the remaining 28 families were represented by only a single species (Table 1). The medicinal value of these families in the flora of Ethiopia is also reported by different ethnobotanists^8,13-15. From these 43 species of them were used to treat for human disease, 19 species of medicinal plants treat for livestock and the remaining 8 species for both human and livestock ailments.

The most frequently reported species were Ruta chalepensis (27 and 67.5%) followed by Hagenia abyssinica (25 and 62.5%) Ocimum lamiifolium (23, 57.5%) and Allium sativum (20 and 50%). Frequently reported of particular medicinal plant species could indicate potentially higher bioactive content to treat different aliments. Such evidence is pertinent for prioritizing future in vivo and in vitro pharmacological research investigation.

Habitat of medicinal plants: With regard to the collection or distribution of medicinal plants in the study area, the majority of medicinal plants were collected from forest or natural vegetation (26 species, 37.14%) followed by home garden (25 species, 35.71%) (Table 2).

Table 1:	Plant families, genera, number of medicinal plant species and proportions

Table 2:	Habitats of medicinal plants in the study area

Other studies also reported that most of plant species used for medicinal purpose in Ethiopia is collected from forest or natural vegetation^2,16,17.

Habit of medicinal plants used for the treat of human and livestock disease: The major habits of the medicinal plants were herbs (47.14%) followed by shrubs (27.14%), trees (18.57%) and climbers (7.14%) (Fig. 2).

Fig. 2:	Percentage distribution of habits of medicinal plants

Fig. 3:	Percentage distribution of plant parts used for remedy preparation

Similar result reported that ethnobotanical investigation conducted in different part of Ethiopia showed that herbs account for higher proportion of medicinal plants^13,15,17-22.

Parts and condition used for remedy preparation: The plant parts most commonly used to treat human and livestock ailments include leaves, root, fruits and others. The most commonly used plant parts for herbal preparations in the study area were leaves (48.57%) followed by seed (11.43%), fruits (8.57%), root (10%). In addition, latex, flower, corm, bulb, stem bark and flower were used for remedy preparation (Fig. 3). In some cases, different parts of the same plant are used for treatment of different ailments. Similarly, other ethnobotanical studies conducted in Ethiopia and elsewhere also showed that leaves as the most commonly used plant parts for remedy preparation^15,17,22-25. One of the reasons that wide utilization of leaves as remedy preparation is that leaf harvesting is relatively a sustainable conservation practice compared to utilization of other plant parts such as root and stem²⁶. The second reason for utilization of leaves for remedy preparation is important because of secondary metabolites or bioactive compounds such as inulins, tannins and other alkaloids which may be account for their medicinal properties are reside on leaves²⁷.

Methods of remedy preparation, dosage and route of administration: Medicinal plant remedies are prepared using grinding, crushing, squeezing, powdering and infusion etc. grinding (38.36%) and crushing (15.07%) were the two commonly used methods in herbal remedies preparation followed by powdering and sniffing (5.48% each) as showed in Table 3. Some of the remedy preparations were prepared from the plant parts either individually or in some cases by the combination of two or more parts of medicinal plants. For instance; leaves of Olea europea subsp. cuspidate for the treatment of Herpes; flower of Hagiena abyssinica with fruit of Embelia schimeri and leaves of Myrsine africana are homogenized together for the treatment of tapeworm; leaves of both Arudinaria alpine and Rumex nervosus with root of Stephania abysinica are homogenized for treatment sudden sickness; dry leaves of Kalanchoe petitiana with fresh leaves of Rumex nervosus for the treatment of homorrage and bulb of Allium sativum with fresh leaves of Foeniculum vulugare for treatment of urinary problem etc. In some medicinal plants have different way of remedy preparation and dosage for the treatment of different types of disease. Water is the major medium in which the decoctions are made. Sometimes, other additives like honey, milk, butter, salt, sugar, coffee or tea were mixed for plant remedies preparation. Some of the remedy preparations had side effects and resulted in vomiting and diarrhea. When such side effect happened, antidotes like milk, whey, cheese, cabbage, chicken soup and ale (local beer) were used to reverse the adverse effect of medicinal plants. Most of the remedy preparations given did not have standardized doses. Therefore; in most cases dosages were determined based on age of the patient, sex and health status of the patient. Pregnant women are also not given those medicines with observable adverse effects such as vomiting and diarrhoea. Some of the medicinal plant preparations were measured in a cup of tea, a glass, jug, nail or full of spoon.

The local healers of the study area employ several collections of plant conditions. About 58 species (82.86%) preparations are made from fresh form, followed by dry 11 species (15.71%) and both dry and fresh 15 (1.43%). The routes of administration of traditional remedies in the study area are various such as Oral, Dermal, Nasal, Ocular and Auditoria.

Table 3:	Percentage of remedy preparation methods

Most of the traditional remedies are taken orally (36 spp., 51.43%) followed by dermal (17 spp., 24.29%) and nasal (5 spp., 7.14) (Fig. 4). This is because of the fact that most of the medicinal plants recorded in the study area are used to treat internal health problem such as stomach ache, intestinal parasites, urinary problem and hepatitis etc., this results are in line with other ethnobotanical investigation conducted in Ethiopia and elsewhere also showed that traditional remedies are mostly administered orally^{14,17,18,28-31}.

Informant Consensus Factor (ICF): During the survey, the medicinal plants of the study area were used to treat a total of 38 ailments (29 in human, 5 in livestock and 4 in both human and livestock ailments). These health problems are generally categorized as infections, general complications, diet related, toxicity related, allergies, devil sickness, wounds and others.

The highest number of medicinal plant species were reported to be used for treatment of sudden sickness (10 species, 14.29%) followed by devil sickness (7 species, 10%); Stomach ache (7 species, 10 %); Wound (5, 7.14%); Common cold, Coughing, Dermal disease (4 species, 5.71% each); Epistaxis (Nose bleed), Headache, Black leg (Shimetere), Taenicides (3 species, 4.29%); Bone fracture, Eye infection, Febrile mill, Hemorrhage, Hepatitis (Koye), Tonsillitis, Tooth ache, Toxic plants (2 species, 2.86% each) as shown in Table 4.

Hence, In this study, the ICF values range from 0.0 for Tonsillitis, Tooth ache, Diabetes, Insect bite, Lash, Malaria etc., to 1.00 for Amoebiasis, Ascriasis, ear infection, gastritis, dysentery etc.

Fig. 4:	Percentage of route of administration of medicinal remedies in the study area

Table 4:	ICF values of ailments treated using the medicinal plants of the study area
ICF: Nur-Nt/(Nur-1), where, ICF is informants consensus factor, Nur is the number of individual plant use reports for a particular illness category and Nt is the total number of species used by all informants for this illness category

Table 5:	Preference ranking of five medicinal plants used for treating wound
K: Key informants. Use criteria (5: Excellent, 4: Very good, 3: Good, 2: Less, 1: Least, 0: No use)

Table 6:	Average score of direct matrix ranking of multipurpose uses of plants in the study area
Use criteria (5: Excellent, 4: Very good, 3: Good, 2: Less, 1: Least, 0: No use)

Thus, most Informant Consensus Factor (ICF) values were above 0.5, which indicated that ailments were widely distributed among the districts. Hence all of them could be considered for validation of isolation and characterization of the bioactive compound by future phytochemical screening.

Preference ranking of medicinal plants used for the treatment of wound: Preference ranking was conducted on the most important five medicinal plants used for the treatment of wound ailments by 10 selected key informants (Table 5). The key informants were selected to identify the best preferred medicinal plant species for treatment of wound and rank the medicinal plants based on their effectiveness against wound and give number 5 for most effective and number 1 for the least effective. The informant consensus revealed that Nuxia congesta occupies the first rank followed by Oncinotis tenuiloba, Salivia nilotica, Bersama abyssinica and Euphorbia ampliphylla. This study is contrary to the work done by Beche et al.³² that Acacia negrii most effective for treatment wound followed by Acacia senegal, Cadaba rotundifolia, Senna petersiana and Ziziphus spina-christi. This was due to the indigenous knowledge on medicinal plants by herbalists varies across culture and ethnic group.

Direct matrix ranking of multipurpose medicinal plants in the study area: Direct matrix ranking was conducted on six multipurpose medicinal plants by 10 selected key informants. The medicinal plants that were investigated other than medicinal value, includes Allium sativum, Cucumis ficifolius, Hagenia abyssinica, Embelia schimperi, Ocimum lamiifolium and Ruta chalepensis. The informant consensus indicated that Hagenia abyssinica, Allium sativum and Ruta chalepensis occupy the first to third rank, respectively followed by others. These medicinal plants have other values such as food/fodder, spice, firewood, construction, market use and others. Direct matrix ranking was done to compare these values of the selected multipurpose medicinal plants (Table 6). Similar result reported that ethnobotanical investigation conducted in different part of Ethiopia showed that direct matrix of a multipurpose use medicinal plants were reported by Bekele³, Bizuayehu and Assefa²² and Abebe and Ayehu³³.

Threats and conservation of medicinal plants in the study area: In this survey, both anthropogenic and natural factors were the major threats of medicinal plant diversity in the study area. Lack of rainfall (25%), deforestation for fire wood (12.5%), lack of awareness on traditional medicine (12.5%), modern public health facilities (10%), over exploitation of medicinal plant, overgrazing by both domestic and wild animals and manufacturing material culture as well as scarcity of land for domestication and/or cultivation of medicinal plant in their homegarden (5% each) and the remaining informants reported that have no threats on medicinal plants in the community. These results are in line with other ethnobotanical investigation conducted in Ethiopia showed that loss of medicinal plant diversity are mostly by agricultural expansion; Overgrazing, Fire wood, Urbanization, Construction and Drought but the threats are vary from one district to others^14,22,34. The most locally threatened medicinal plant in the study area is Hagenia abyssinica, Embelia schimperi, Ajuga integrifolia and Myrsine africana. Some of the herbalists are interesting to cultivate some of the medicinal plants in their homegarden.

CONCLUSION AND RECOMMENDATIONS

The study indicated that the Ezha district have rich in medicinal plants and associating traditional knowledge that are concerning the use of medicinal plants for the treatment of both human and livestock diseases. Traditional knowledge’s on medicinal plants are play important role to maintain their primary health care of the community.

Many herbalists reported that the poly-herbal medicine have high healing ability than the use single medicinal plant as a remedy. Most of the medicinal plants were collected from natural vegetation, which implies better achievement of in situ conservation in the communities and the communities also have the better habit of conserving plant genetic resources in their natural habitat. For the sustainable use of medicinal plants in the community, there is a need to develop a conservation strategy and promote medicinal plants growing in their homegardens and protect it’s in their natural habitat.

According to the result of the study, the following recommendations are forwarded:

ACKNOWLEDGMENTS

We would like to acknowledge Research and community service office of Wolkite University for guidance, constructive comments and financial support. We also acknowledged the biodiversity and environment protection office of Ezha district as well as traditional medicinal practitioners for their hospitality, respect and kind response to the inquiries on the information regarding their devoted experience to keep indigenous knowledge on traditional medicinal plants. We also like to thank our staff member Mr Belay Zerga (PhD candidate in Addis Ababa University) for explain the Yotyet-yewezera and Amba Natural forest during reconnaissance survey. Finally we appreciated two anonymous reviewers (Mr. Belachew Garedew and Mr. Zemedekun Siraj) for their valuable comments to improve the research manuscript quality.