Thymus species in Ethiopia : Distribution , medicinal value , economic benefit , current status and threatening factors

The genus Thymus is one of the genera in the family Lamiaceae. In Ethiopia, it is represented by two endemic species namely Thymus serrulatus and Thymus schimperi. The aims of this study were to identify the types of species from six geographically distant localities in Ethiopia, assess the ethnobotanical and socioeconomic information of these species in these localities and gather information about the current status and threatening factors of these species in the six localities. The plant specimens from these localities were authenticated by experts in the National Herbarium of Addis Ababa University as Thymus serrulatus and Thymus schimperi. The plants were rated by local informants as treatments for ailments like blood pressure (30.7%), general pain syndrome (10%), influenza (10%), abdominal pain (10%), ascariasis (2.9%), and intestinal parasites (2.9%). The informants rated the economic value of these plants as animal forage (71.5%), bee forage (71.5%), condiments (68%), and washing and fumigation (46%). According to the informants, the status of Thymus species is declining from time to time due to overgrazing (80.7%), agricultural expansion (64.2%), overharvesting (48.57%), uprooting during harvesting (14.2%), and lack of recognition (13.6%)

In the different parts of the world, Thymus extracts are traditionally used orally to treat dyspepsia and other gastrointestinal disturbances, bronchitis, pertussis, laryngitis and tonsillitis, and coughs due to colds (Belaqziz et al., 2010;Özgen et al., 2011).Topical applications of thyme extracts have been used in the treatment of minor wounds, the common cold, and disorders of the oral cavity, and as an antibacterial agent in oral hygiene (Özgen et al., 2011).
Traditionally, Thymus species in Ethiopia are used in a variety of forms (Malcolm and Zelalem Tefera, 2007).The fresh or dried leaves of these species are used locally as condiments and tea (Sebsebe Demissew and Nigist Asfaw, 1994); in the preparation of berbere and "shirro" (pepper and bean/pea powder) (Amare Getahun, 1976); for the preparation of Metata ayb (a traditional Ethiopian fermented cottage cheese) (Eyassu Seifu, 2013).
The major constituents of T. schimperi and T. serrulatus in Ethiopia are thymol and carvacrol (Nigist Asfaw et al., 2000).All the pharmacological actions of thyme thus may be due mainly to the phenolic component thymol, which is a major component in their essential oils (Sebsebe Demissew and Nigist Asfaw, 1994).In addition to their medicinal values, Thymus species in Ethiopia have economic uses like animal feed and bee forage (Likawent Yeheyis et al., 2008).
The present study thus was designed (1) to identify the types of Thymus species from six distant localities in Ethiopia (2) to collect information about their medicinal values, their economic benefits, their current status and pressures or threatening factors on these species.

Study area
Samples of Thymus species, ethnobotanical information, socioeconomic data, and threatening factors were collected from six localities of Ethiopia (Figure 1).1).
Ofla woreda has an altitudinal range of 1800-2440 m.Its mean annual rainfall is between 700-800 mm with mean daily temperatures ranging from 10-22 ºC.Rainfall is bimodal; a short rainy season "belg" between February and May, and a long rainy season "meher" between June and September.Mixed crop-livestock production is the major activity of the farming system.Wheat, maize, barley, faba bean and sorghum are the major crops grown.The major livestock types reared in the district are cattle, sheep and chicken.Donkeys, goats and honeybees are also reared having lower shares (Girmay Tesfay et al., 2014).
Favorable climatic condition and fertile soil makes the woreda suitable for crop production and livestock husbandry.In the woreda, the rural people depend on crop production and livestock husbandry for their Livelihood.Cropping is predominantly rain fed.As part of mixed farming, the woreda possesses cattle, sheep, goats, equine poultry and bee hives.This woreda is one of the major maize producers followed by Teff, Barley and Wheat (Solomon Abie, 2011).
Tarmaber is located 190 km away from Addis and covers about 54,000 ha of lands.Agro climatologically 17% of the land is lowland, 28 % semi-arid (Woinadega) and 54.7 % is highland (Dega).Its altitude is ranging from 1500 to 3100 meter above sea level.The average annual temperature and the mean monthly rain fall are about 15.5 °C and 1200 mm respectively.The topography is dominated by chain of hills and rouged mountains; thereby 15.28 % of the woreda is mountainous, 32.78 % is plain lands, 6.29 % valleys and 45.65 % are rugged types (http://edaethiopia.org/index.php/wherewe-work/amhara/tarma-ber).
Meskana Mareko is a district located in the Gurage zone, Southern Nations, Nationalities, and People's  er et al., 2008).The trend of the rainfall distribution is bimodal namely "belg" (small rains occurring from February to May) and "kiremt" (big rains occurring from August to October) (Luizza et al., 2013).Dinsho's loamy, fairly fertile, and low-density Mollic Andosol soils are results of extended weathering of lava outflows stemming from the Oligocene Epoch (33.9 -23 million years B.P.) (Luizza et al., 2013).It has a typical vegetation type of undifferentiated Afromontane forests.The predominant inhabitants are the Oromo people who use economic activities primarily based upon mixed farming that involves pastoralism and cultivation of crops such as wheat and barley (Haile Yineger et al., 2008).

Data collection
This information about T. serrulatus and T. schimperi species were collected from informants using semi-structured questionnaires.The development agents (DAs) in each study site were involved in the informant selection and data collection processes.
The informants in each study site were farmers who had meetings with the DAs.A total of 140 male informants were randomly selected and asked about the medicinal value, economic advantage, current status, and threatening factors of Thymus species in their localities.Data collection took place from 28 th July through 28 th September 2013.

Plant material identification
Samples of the aerial parts of Thymus species were collected from 28 th July through 28 th September 2013 from the above mentioned districts and regions.The

Identified Thymes species collected from six localities in Ethiopia
Out of the Thymus species collected from six localities, three of them (Ofl-2013, Ala-2013, and Yil-2013) were identified as T. serrulatus and the rest three (Tar-2013, But-2013, and Bal-2013) as T. schimperi (Table 1).

Medicinal value of T. schimperi and T. serrulatus from Ethiopia
The majority of the respondents 43 (30.7%) have at least heard about the use of Thymus species as a treatment for blood pressure although a lot of them 33 (23.5%) have no information about the health significances of these species.On the other hand, 52 (30%) of the respondents have mentioned that these plants have applications to treat general pain syndrome, influenza and abdominal pain (Table 2).Some respondents from Tgray Region mentioned the ascaricidal 4 (2.9%) and intestinal paraciticidal 4 (2.9%) effects of T. serrulatus grown in Tigray.In almost all the localities, the respondents mentioned that it is the aerial parts of T. schimperi and T. serrulatus which are dried, crushed, made into tea and taken orally to treat the ailments mentioned.

benefits of T. schimperi and T. serrulatus from Ethiopia
The respondents mentioned the economic uses of Thymus species in Ethiopia as honey bee forage, animal forage, food additives (condiments), and washing and fumigating household utensils such as buckets for milking and dough preparation (Table 3).The respondents further mentioned that such fumigation of milking jars and buckets for putting milk and dough of injera is important to maintain milk and injera with best flavors and without rancidity.According to the respondents, the honey from Thymus species has medicinal value and with special taste.Milk, yogurt, butter, and meat from animals fed with Thymus species have special taste and flavor.In addition, application of Thymus species as food additives increases the flavor and shelf-life of foods and sauces such as shiro, berbere, butter, Besso etc. Furthermore, the respondents have mentioned that Thymus as an animal forage is useful for fattening.Furthermore fumigating the honey beehives attracts honey bees and eliminates honey bee diseases as was raised by the respondents from Southern Tigray.During interview with the respondents, it was clear that more people from other areas of the country use Thymus species as food additives than people in Southern Tigray.The people in Tigray know that it can be used as tea but most of them do not use it.*Amh-Amharic; Gur-Guragigna, Tig-Tigrigna, Oro-Oromipha l Ofl-T.serrulatusfrom Ofla, Ala-T.serrulatus from Alamata, Yil-T.serrulatus from Yilmana Densa, Tar-T.schimperi from Tarmaber, But-T.schimperi from Butajira, Bal-T.schimperi from Bale.

Current status and threatening factors of Thymus species from Ethiopia
According to the respondents' responses, Thymus species endemic to Ethiopia (T.schimperi and T. serrulatus) exist as wild species and their current status is decreasing from year to year (Table 4).The major threatening factors for these species were identified to be overgrazing followed by agricultural expansion, overharvesting, harvesting the whole plant including the roots, and lack of recognition.
This reduction in Thymus species is high in North Shewa and Gurage zone due to the mentioned threatening factors.However, the situation is better in Tigray (Alamata and Ofla), Yilmana Densa (West Gojjam) and Dinsho (Bale) since the collection sites are closed from human and animal encroachment.
Harvesting the whole plant including the roots is the biggest problem in North Shewa due that the plant is served as an income source for inhabitants there.It is usual to see the youth and women selling the dried plant parts to travelers on the highway from Addis Ababa to North Ethiopia (Wello and Tigray).*Amh-Amharic; Gur-Guragigna, Tig-Tigrigna, Oro-Oromipha

DISCUSSION
While Thymus specimens collected from the Northern parts of Ethiopia (Tigray and Gojjam) were found to be T. serrulatus, those collected from central (Shewa) and Southern (Bale and Butajira) were T. schimperi.
The medicinal value of Thymus serrulatus and Thymus schimperi were identified by the respondents as; to treat blood pressure, to treat general pain syndrome, influenza, abdominal pain, and to treat intestinal parasites like ascaris.Literature supports these bioactivities of Thymus species.For example the work by Miloradovic et al. (2010) showed that thyme extract (TE-T.serpyllum L.) resulted in a significantly reduced level of Systolic Atrial Pressure (SAP) and Diastolic Atrial Pressure (DAP) in hypertensive rats.
In addition, T. vulgaris was found to reduce pain in mice while applying to plate, tail flick and formalin tests (Taherian et al., 2009).So it is not surprising if T. serrulatus and T. schimperi act as treatments for general pain syndrome.Essential oils of thyme are also known for their antivirus, antibacterial, antifungal and antiworm activities owing to their active component thymol (Lezak, 2000).This may be the reason why T. serrulatus and T. schimperi are used for treating intestinal parasites and abdominal pain.Furthermore, thymol is the major component of Thymus species from Ethiopia.For example the works of Ermias Dagne et al. (1998) and Nigist Asfaw et al. (2000) revealed that the components of T. schimperi were by large thymol 50% and more than 30%, respectively.
In addition, the abdominal pain reliving capacity of these plants may be due to their abilities to kill Helicobacter pylori (Esmaeili et al., 2012) and their anti-acidic nature.et al. (2009) showed that thyme honey reduces the viability of prostate cancer cell line (MCF-7).Thus, the information from the informants is valuable.
According to the informants, the status of T. serrulatus and T. schimperi is declining mainly due to over- problem is commercialization of these wild species without conserving them (Zuzarte et al., 2011).This may be due to the reason that wild species are communal and no one cares about them as private (cultivated) species.Their multiple use as condiments, forage, medicinal value, and tea increased the harvesting pressure on these plants and they are continuously declining.In the same way all these pressures may be indirectly caused by human population expansion and increased level of unemployment rate (Wangchuk et al., 2008).In addition, there is continuous and bulk requirement of these herbs.To supply such large quantity of the herbs, large scale cultivation would be required, which in turn will generate good business opportunities and human resource development (Tripathi et al., 2009).

CONCLUSIONS
The specimens of Thymus collected from Southern Tigray (Alamata and Ofla) as well as from West Gojjam (Yilmana Densa) were found to be T. serrulatus while those collected from Tarma Ber, Buta Jira, and Bale were T. schimperi.Many of the informants agreed about the importance of these species to treat blood pressure followed by general pain syndrome, 7 o c (Dawit Gebregziabher, 2010).Alamata has bimodal rainfall patterns; the belg (short rains) (from January to February) and the Meher (long rains) (from July to August).The mean annual rainfall of the area is around 963.5 mm.Teff and sorghum are the dominant crops covering 75% of the woreda caltivated area.Currently field pea, faba bean, lentils (in high land) teff and pepper (in low land) are the most important marketable commodities in the woreda.Livestock production in the woreda involves cattle, sheep, goats, camel, poultry and bee production (IPMS, 2005; Dawit Gebregziabher, 2010).

Figure 1 :
Figure 1: Data/Sample Collection Sites of Thymus species for the present study (constructed from GPS data) Regional state (SNNPR) 135 km south of Addis Ababa.The dominant ethnic group is Gurage of meskan dialects.Farming is the main economic activity and the main cash crops are pepper, coffee and khat.The woreda lies at an average altitude of 1900 m above sea level, ranging from 1750 m a.s.l in the lowlands to 3400 m a.s.l in the mountains.Annual rainfall in Meskana Mareko area ranges between 700-1870 mm.Although the main rainy season is from June to September, light rains are common around March and April.The warmest months are between January and June with a maximum temperature of 30.4 °C in March during the last ten years.During the last decade the annual mean maximum temperature was 26.3 °C and minimum mean temperature was 11.1 °C (Solomon Tesfaye et al.,2012).Dinsho Woreda is one of the districts in Oromia Region.Dinsho is located at the northern edge of the Bale Mountains National Park (BMNP) 370 Kms South East from Addis Ababa.It has altitudinal ranges from 2441-3600 m a.s.l.(Haile Yineger et al., 2008).Its mean annual temperature and rainfall are 10.26 o C and 1218.64 mm respectively (Haile Yineg- collected specimens were pressed and taken to National Herbarium of Addis Ababa University for authentication.They were identified by Mr. Melaku Wondafrash in the National Herbarium of Addis Ababa University.After identification, voucher specimens were deposited in the Natural Herbarium of Addis Ababa University with voucher numbers Ala-2013 (Thymus from Alamata district), But-2013 (Thymus from Butajira, Meskana Mareko woreda), Bal-2013 (Thymus from Dinsho, Bale Mountains National Park), Ofl-2013 (Thymus from Ofla district), Tar-2013 (Thymus from Tarma Ber, Mojana district) and Yil-2013 (Thymus from Yilmana Densa district).
grazing followed by agricultural expansion, overharvesting, harvesting the whole plant including the roots, and lack of recognition.The threatening factors for these plants are similar to those identified byKalayu Mesfin et al. (2013).Harvesting the whole plant including the root continuously is a dangerous practice which interferes with the life cycle of the species and results in eradication of the whole plant(Wangchuk et al., 2008).These plants are restricted to limited geographical regions (Alpine and Afroalpine) so that degradation of these areas may result in degradation of the whole species.Overgrazing of T. serrulatus and T. schimperi is a big challenge owing to their suitability as forages for cattle, sheep and goats as well as the beliefs of inhabitants that animals which fed these plants give tasty meat, mutton, and milk.The other influenza, abdominal pain, and intestinal parasites like Ascaris in descending order.However great majority of them especially those from Tigray do not know about the medicinal uses of these plants.Economically, these plants are important sources of animal and honey bee forage, serve as condiments, tea, and fumigants.Despite their medicinal and economic uses, these plants are highly diminishing due to overharvesting, overgrazing, agricultural expansion, whole plant harvesting including the roots, and lack of recognition.
These localities were Ofla and Alamata woredas

Table 2 .
Human ailments reported to be treated by T. schimperi and T. serrulatus