Geographic Location and Description of the Study Area
The study was conducted in Tiyo District of East Arsi Administrative Zone, Oromia National Regional State of Ethiopia (Fig. 1).
The area is located at about 175 Km southeast of Addis Ababa. The Addis Ababa-Asela all-weather road provides the primary access to the District. Geographically, Tiyo District is found approximately between 70 45' 55'' and 80 02' 02'' N latitude and 38o 56' 42'' to 39o 18' 31'' E longitude. It is located just on the top of the eastern edge of the Ethiopian Rift Valley. Topography of the District is a part of the Arsi-Bale Mountains chain in general and Chilalo-Galama Mountains in particular. The District is characterized by flat (00) to very steeply topographic features (58.60). Its altitude ranges from 1850 to 4050 m.a.s.l. The District is characterized by three agroecological zones: Dega (highland) is about 52%; Woyenadega (middle land) about 37% and Kola (lowland) is 11%.
Climate
According to the records of the National Meteorological Agency (NAMA) of Ethiopia, the mean annual rainfall of the District is 1100 mm. Distribution of the rainfall is bimodal, which occurs in the major rainy season (Kiremt) and the short rainy season is (belg). The major rainy season occurs from June to October and the short rainy season occurs in March, April and May. The dry season extends from November to February. The mean annual maximum temperature was 23.1oC and the mean monthly maximum values ranged from 21.1 to 25oc.
The mean annual minimum temperature is 9.1oc and the mean monthly minimum values ranges from 7.1 to 11oc. The coldest months were October, November and December whereas March, April and May were the hottest months of the years NMA, 2004–2013 (Fig. 2).
Sampling Study Sites And Informants
Study sites were selected purposively through feasibility study based on the agro-ecological zones of the district (lowland, middle and highland) because such stratification can represent the whole district. This helps for the effective evaluation of the distribution of medicinal plants and the variability of traditional knowledge in different agro-climatic zone. The Kebeles selected are shown in Fig. 1.
Representative informants were selected through systematic random sampling by flipping a coin for household and/or for individuals to be selected based on the age, sex and educational background. When the coin comes up a head, the informant was selected, if tail comes up the informant was not selected following the method recommended by Martin [1]. This helps to provide equal statistical chance to all members of population with the age ranges between 18 and 75, different sex and level of educational back ground, etc. Knowledgeable informants were selected by using purposive sampling methods based on recommendation obtained from elders and local authorities (Development Agents and kebele administration leaders). The total sample size was decided by using the following simplified formula following Yamane Taro [18]:
Table 1 summarizes number of households and sample size in each Kebele.
Table 1
Number of Households and sample sizes in each Kebele (Lowest administrative units) in Tiyo District, Arsi Zone, Ethiopia.
Name of the kebele
|
No of Household
|
Sample size
|
Oda Deweta
|
1094×153
|
19
|
|
8643
|
|
Gora Silingo
|
1260
|
22
|
Burka Chilalo
|
889
|
16
|
Dosha
|
789
|
14
|
Dugdea Ukulu
|
|
714
|
13
|
|
|
Murkicha Kobo
|
658
|
12
|
Abosera Alko
|
972
|
17
|
Haro Bilalo
|
985
|
17
|
Bore Chilalo
|
1280
|
23
|
Total
|
8641
|
153
|
General Features Of The Respondents
A total of 153 respondents (84 males and 69 females) grouped into four age classes, 18–30, 31–45, 46–60 and 61–75 (Table 2) were involved in this study with age ranges from 18–75 and an average age of 45 years. From the total respondents fifty knowledgeable informants were selected based on recommendation of elders and local authorities. From fifty knowledgeable informants 26 key informants were selected and involved in different exercises.
Table 2
Age, educational status and occupation of the respondents in three agro-ecological zones of Tiyo District, Arsi Zone, Oromia, Ethiopia.
Variables
|
Low
land
|
|
Middle
|
|
High
land
|
|
|
|
N=(46)
|
%
|
N=(56)
|
%
|
N=(51)
|
%
|
Total
|
%
|
Informants category
|
Key informants
|
14
|
30.43
|
20
|
35.71
|
16
|
31.37
|
50
|
32.68
|
General informants
|
32
|
69.57
|
36
|
64.29
|
35
|
68.62
|
103
|
67.32
|
Age
|
18–30
|
10
|
21.74
|
13
|
23.21
|
12
|
23.53
|
35
|
22.88
|
31–45
|
11
|
23.91
|
14
|
25.00
|
12
|
23.53
|
37
|
24.18
|
46–60
|
13
|
28.26
|
14
|
25.00
|
13
|
25.49
|
40
|
26.14
|
61–75
|
12
|
26.09
|
15
|
26.79
|
14
|
27.45
|
41
|
26.80
|
Education
|
Illiterate
|
17
|
36.96
|
14
|
25.00
|
16
|
31.37
|
47
|
30.72
|
Read and Write
|
12
|
26.09
|
15
|
26.79
|
14
|
27.45
|
41
|
26.80
|
Primary
|
7
|
15.23
|
18
|
32.14
|
8
|
15.68
|
33
|
21.57
|
Secondary
|
5
|
10.87
|
10
|
17.86
|
5
|
9.80
|
20
|
13.07
|
Diploma
|
3
|
6.52
|
2
|
3.57
|
1
|
1.96
|
6
|
3.92
|
Religious studies
|
2
|
4.35
|
2
|
3.57
|
2
|
3.92
|
6
|
3.92
|
Occupation
|
Farmers
|
41
|
89.13
|
52
|
92.86
|
46
|
90.20
|
139
|
90.85
|
Merchants
|
1
|
2.17
|
2
|
3.57
|
2
|
3.92
|
5
|
3.27
|
Herbalist
|
4
|
8.70
|
2
|
3.57
|
3
|
5.88
|
9
|
5.88
|
The informants in this study were comprised of four different age category and this helped to evaluate their views on traditional medication system, indigenous knowledge maintained, traditional conservation methods and management system practiced by society of different age groups. A larger of the informants (31.65%) were illiterate. The major occupation of the informants is agriculture and have long year of experiences in using vegetation of their surroundings for their daily life and this helped to get informants with deep knowledge on traditional medicine.
Data Collection Methods
Ethnobotanical data were collected from October 1/2013 to January 30/2014 in several field trips, closely working with and clearly mentioning the aim of the study to informants to obtain clear and objective responses through different ethnobotanical methods. Semi-structured interview, focus group discussion, guided field walk, free listing, informants’ consensus, preference ranking, direct matrix ranking, paired comparison and fidelity level index were used for collecting data as described below.
Semi-structured Interview
Semi-structured interview was conducted using prepared questions in Afaan Oromo, which is the local language of the informants following the accepted practice [1, 12]. During interview, issues regarding name, age, sex, level of education, occupation, religion and ethnicity of the informants were included. Moreover, informants were asked about the local name of the medicinal plants used, human and livestock ailments treated, plant parts used, condition of plant parts used (fresh or dried), other ingredients or additives if any, methods of remedy preparation, source of knowledge, methods of traditional knowledge transfer and number of years of services as traditional healers were focused in detail.
Focus Group Discussion
Discussion with knowledgeable informants over all kebeles were also designed and performed so as to gather further information on medicinal plants and in general to prove reliability of information gathered during semi-structured interview.
Guided Field Walk
Two to three field walks were made as necessary with knowledgeable informants and this provided an opportunity for more discussion with the herbalists’ and the practical identification of traditionally used medicinal plants in their natural environment. It also helps to obtain firsthand impression on the abundance, habit and habitat characteristics of the plant species mentioned during interviews. During this observation medicinal plant species were identified, specimens collected and photographs were taken.
Free Listing
In this exercise the informants were asked to list all medicinal plants which are used for a particular purpose. The medicinal plants which are more significant were more likely to be mentioned by several informants.
Informant Consensus
In order to evaluate the reliability of information recorded during the interview, informants were visited more than one times for the same ideas and the validity of the information was proved and recorded. Consequently, if the idea of an informant deviates from the original information, it was rejected since it was considered irrelevant information. Only the relevant ones were taken into account and statistically analysed by the methods adopted from Alexiades [19]. Informant Consensus Factor (ICF) was calculated for each category to identify the agreements of the informants on the reported cures for the group of ailments as: number of use citations in each category (Nur) minus the number of species used (Nt), divided by the numbers of use citations in each category minus one [20].
Where ICF = Informants Consensus Factor
Nur = Number of use citation in each category
Nt = Number of species used
Preference Ranking
Nine key informants took part in preference ranking exercise in the manner recommended by Martin [1] to identify the most preferred plants among 12 medicinal plant species used for treating the most common ailments in the study area and to prioritize the most threatening factors on vegetation of the study area in general and medicinal plants in particular. Medicinal plants were arranged based on the personal preference on their efficacy. In this exercise, the set of medicinal plants namely: Solanum campylacanthum, Helichrysum elephantinum, Kalanchoe petitiana, Calpurnia aurea, Podocarpus falcatus, Solanum somalense, Asparagus africanus, Coccinia abyssinica, Stephania abyssinica, Datura stramonium, Clematis simensis and Phytolacca dodecandra were selected from the list of medicinal plants that were reported by most informants in treating rabies in the study area. They were provided to those randomly selected key informants to rank them based on the efficacy of their medicine. Each informant gave a numerical score of 1, 2, 3, 4 to 5 with the most effective receiving the highest number (5). The medicinal plant supposedly most effective were given the highest value and the least effective one was given the lowest value. Finally, total values were calculated and an overall ranking was determined.
Direct Matrix Ranking
Data on the multipurpose use of medicinal plants were evaluated and compared through direct matrix ranking exercise as described in Martin [1], by involving key informants who have long years of experiences as traditional herbal medicine practitioners in the study area. The multipurpose plant species commonly reported by informants were selected out of the total collected medicinal plants and use diversity of these plants were listed by key informants who ordered them by considering several attributes at a time. For instance (5 = most valuable, 4 = very good, 3 = good, 2 = less used, 1 = least valuable, and 0 = not used). Accordingly, the use values given for each multipurpose medicinal plant by each key informant were averaged and the values of each species summed up and ranked.
Paired Comparison
A paired comparison was conducted for five medicinal plants that were used for treating wart. Nine key informants participated in the paired comparison. Accordingly, Euphorbia dumalis was first followed by Lepidium sativum as shown in Table 12. This result indicated that Euphorbia dumalis was much favored over other plant species cited for treating wart in the area. Moreover, the result could be a testimony for the efficacy of these two plant species to treat wart at least in the study area.
Table 12
Paired comparison of medicinal plants used to treat Wart in Tiyo District, Arsi Zone, Oromia, Ethiopia.
Plant species
|
Respondents
|
Total
|
Rank
|
I1
|
I2
|
I3
|
I4
|
I5
|
I6
|
I7
|
I8
|
I9
|
Euphorbia chumalis
|
5
|
5
|
4
|
4
|
5
|
4
|
4
|
5
|
5
|
41
|
1st
|
Lepidium sativum
|
5
|
4
|
4
|
5
|
4
|
5
|
5
|
4
|
3
|
39
|
2nd
|
Dodonaea angustifolia
|
4
|
5
|
2
|
5
|
5
|
5
|
4
|
4
|
4
|
38
|
3rd
|
Verbascum sinaiticum
|
4
|
3
|
5
|
3
|
4
|
4
|
5
|
5
|
4
|
37
|
4th
|
Euphorbia
|
4
|
3
|
3
|
4
|
4
|
5
|
5
|
4
|
4
|
36
|
5th
|
candelabrum
|
Fidelity Level Index
Many plant species were used in the same use category that necessitated to determine the most preferred species used in treatment of a particular ailment, which can be done with the fidelity level [22]. The fidelity level (FL), is the percentage of informants claiming the use of a certain plant species for the same major purpose. It was calculated for the most frequently reported diseases as:
Where Np is the number of informants that claim the use of a plant species to treat a particular disease, and N is the number of informants that use the plant species as a medicine to treat any given disease [19].
Review Of Secondary Sources
Data of secondary sources were reviewed from public and livestock health centers to evaluate their view of traditional medication system, to obtain the list of the most frequent health problems in the District, Agricultural and Rural Development office of the district to gather information about the socio-economic, demographic, location, climatic (ten years climatic data), edaphic and vegetation characteristics of the study area. In addition, information on the working cooperation between modern health practitioners and traditional herbalists were gathered.
Voucher Specimen Collection And Identification
All interviews, discussions as well as field surveys were accompanied with voucher specimen collection that was carried out with the help of traditional healers and local field assistants. The specimens were air-dried, numbered, labelled, pressed, heater-dried, deep-frozen, identified and deposited at the National Herbarium (ETH) in Addis Ababa University. Identification of specimens were performed both in the field and later at ETH using taxonomic keys and the relevant volumes of the Flora of Ethiopia and Eritrea [23–29].
Ethical Consideration
All participants in this ethnobotanical survey were informed about the detailed objectives of the research before starting any data collection and information sharing. Informants were clearly informed that the results will be used for academic purposes only not for commercial purpose. The procedure involved asking permission of the local administration and each informant.
Data analysis
Ethnobotanical data analysis
Descriptive statistical methods (both qualitative and quantitative analytical tools) were used for data analysis following Martin [1] and Cotton [12]. Data on informants’ background, medicinal plants used and associated traditional knowledge were entered in Excel spread sheet software and organized for statistical data analysis. Traditional knowledge dynamics on use of medicinal plants by men and women, young to middle aged and elder; literate (completed at least primary education) and illiterate, knowledgeable (key) and local (encountered randomly) informants were compared by using SPSS and Excel software.
Descriptive statistical methods were also applied to analyze medicinal value, methods of preparation, application techniques, route of administration, disease treated, plant parts used and habit of medicinal plants. In addition, six categories of plant use-reports, frequency and relative frequency of tree species were employed to analyze data statistically.