Bokh

ETHTIPA012
Map of tropical important plant area site of Bokh

Country: Ethiopia

Administrative region: Somali (Regional State)

Central co-ordinates: 7.18700 N, 46.71900 E

Area: 5061km²

Qualifying IPA Criteria

A(i)Site contains one or more globally threatened species

IPA assessment rationale

This site qualifies as an IPA under criterion A(i) due to the presence of two globally threatened species: the socio-economically important tree, Cordeauxia edulis (EN), for which this IPA is a key locality and one of the last remaining sites globally; and Merremia warderensis (CR), for which this site is the only known locality, based on one georeferenced herbarium voucher in the southwestern corner of the IPA, suggesting high site irreplaceability. While further botanical exploration in the region may reveal a more widespread distribution for Merremia warderensis, this site is of global importance for the species.

Site description

The Bokh IPA is situated in the Dollo Zone (previously known as the Warder Zone) of Somali Regional State, in the eastern Ethiopian lowlands. It extends across three woredas (districts), namely Bokh, Galadin and Galhamur, and lies approximately 450 km southeast of Jijiga, the capital city of Somali Regional State. Specifically, the IPA borders the towns of Geladin to the south, and Jiracle and Boh to the north, the latter being an important trading centre for local communities and the surrounding areas (Yusuf et al., 2013a).

There are a number of small villages within Bokh IPA, and the eastern part of the site runs parallel to the Ethiopia-Somalia border. Galkayo, Somalia's third-largest city, is located approximately 50 km southeast of the IPA. The Bokh area is one of only two regions thought to still contain the globally threatened tree species, Cordeauxia edulis (EN), which has drastically declined in recent decades and is threatened by livestock farming, resource overexploitation and climate change (Drechsel & Zech, 1988; Beech et al., 2018).

Botanical significance

Bokh IPA is situated in the Ogaden, a floristically underexplored territory in eastern Ethiopia, attributable to decades of security issues and socio-political tensions (Sebsebe & Dioli, 2000; Mabberley, 2009). Across the Ogaden, the abundance of endemic plant species is thought to be higher than in most other areas of Ethiopia, with great potential for the discovery of new species (Dioli, 2002; Thulin, 2011; cited in Thulin & Vollesen, 2015; Friis et al., 2016).

The IPA is a key locality for the socio-economically important tree, Cordeauxia edulis (EN), locally known as Yeheb (Drechsel & Zech, 1988; Mekonnen et al., 2010; Yusuf et al., 2013b; Seyoum & Mekbib, 2014; Beech et al., 2018). This species was once widespread throughout the Ogaden, extending into central Somalia, but by 1988 the species' distributional range had declined significantly, with only two known localities in Ethiopia - the Werder and Bokh regions (Drechsel & Zech, 1988). The current distribution of Cordeauxia edulis in Ethiopia may, in fact, now be restricted to the Bokh region (Mekonnen et al., 2010; Yusuf et al., 2013b; Sebsebe Demissew, pers. comm.). Fieldwork in June 2021 revealed the presence of Cordeauxia edulis at six sites within the IPA: near Mirafadle Kebele, Gambarey, Maned Kebele, Dabhabalan Kebele, Foya adde Kebele and Shilinbur (Abubaker et al., 2021).

The endemic geophyte, Merremia warderensis (CR), is also known to occur in the surrounding areas, supported by a herbarium voucher from the southwestern corner of the IPA (Sebsebe, 2001). Further fieldwork is required to determine the abundance and distribution of this species.

Habitat and geology

The topology of the IPA is characterised by desert to semi-desert lowlands. White (1983) and Friis et al. (2010) categorised the area as a mix of Acacia-Commiphora woodland and bushland, and desert and semi-desert scrubland. Land cover within the IPA consists of Haud-type mixed bushland (Acacia-Commiphora), open scrubland and grassland, rocky outcrops and urban areas. The Acacia-Commiphora bushland, also referred to as Haud-type mixed bushland by Drechsel & Zech (1988), varies from thickets to low open scrub, dominated by drought resistant and semi-succulent species. Open grassland is dominated by Aristida kelleri, Aristida paoliana and Stipagrostis uniplumis (Hemming, 1966; Drechsel & Zech, 1988). Other grasses include Cenchrus ciliaris, Cenchrus stramineus, Dactyloctenium scindicum, Digitaria rivae, Eragrostis papposa, Leptothrium senegalense, Tetrapogon cenchriformis and Tetrapogon roxburghiana (Hemming, 1966).

In addition to Cordeauxia edulis, scattered thickets across the Bokh region comprise Albizia anthelmintic (LC), Balanites rotundifolia var. scillin, Cordyla somalensis (NT), Delonix baccal, Euphorbia cuneata (LC), Fagonia lahovari, Gyrocarpus hababensis, Indigofera ruspoli, Senna italica, Sesamothamnus rivae, Terminalia orbicularis, Vachellia (Acacia) horrida, Vachellia (Acacia) tortilis (LC) and various species of Boswellia, Commiphora, Cordia and Grewia (Hemming, 1966; Drechsel & Zech, 1988; Yusuf et al., 2013b). Where Cordeauxia edulis is locally abundant, the density of other tree species appears to be relatively low, whereas in areas where Yeheb has been locally overexploited (for instance, the villages of Foye ade, Maned and Dab-habalan), other species begin to dominate (Abubaker et al., 2021). These include Acacia horrida, Acacia tortilis (LC), Boswellia microphylla, Boswellia neglecta, Cassia obovata, Cordia africana (LC), Euphorbia cuneata (LC), Indigofera ruspoli, Terminalia orbicularis and a number of Commiphora species (Abubaker et al., 2021).

Lithologically, the area is dominated by the Bokh formation, comprising shale interbedded with sandstone and siltstone (Worku & Astin, 1992; JICA, 2013; Oljira et al., 2020). Gypsum and limestone outcrops are also widely exposed in the Bokh and Galadi woredas (Hemming, 1966; Drechsel & Zech, 1988; JICA, 2013). According to Drechsel & Zech (1988), soil within the IPA is characteristic of the Haud, consisting of red sandy soil, with a high rainwater filtration rate, derived from the Jesomma formation. The red soils of the Galadin woreda are often deeper, with traces of lime (Drechsel & Zech, 1988). Petric and haplic gypsosols also occur.

The climate of the Bokh area is arid, part of the Bereha climatic zone (Mege et al., 2015), with a mean annual temperature of 28 C (Yusuf et al., 2013b). Rainfall is bimodal with two rainy seasons (March-May and October-November), and two prolonged dry periods (Drechsel & Zech, 1988; Seyoum & Mekbib, 2014). Mean annual rainfall varies from 150-250 mm (Drechsel & Zech, 1988; Yusuf et al., 2013b).

Conservation issues

There is currently no site protection or biodiversity management plan within the IPA, nor does the IPA overlap with an Important Bird Area or Key Biodiversity Area. This is perhaps, in part, a result of the socio-political tensions and territorial disputes that have presided over the region for many years, hampering botanical exploration and conservation efforts (Hogg, 1991; Mabberley, 2009; Mohamed & Iman, 2010; Mohamed, 2013). The region is also prone to prolonged periods of drought, likely exacerbated by increasing weather unpredictability and climate change. Cordeauxia edulis is considered to be relatively drought resistant and desertification tolerant (Yusuf et al., 2013; Abubaker et al., 2021), but it remains unclear how future climatic changes will affect the species.

Overgrazing from livestock is the main threat to Bokh IPA and its floristic diversity. Over 85% of the human population across the Ogaden are pastoralists (Yusuf et al., 2013a), exerting significant pressures on the region's natural habitat. The globally threatened species, Cordeauxia edulis (EN), has declined by 50% over just three generations (less than 180 years) due to overexploitation by local communities, overgrazing and severe droughts (Thulin & Vollesen, 2015; Beech et al., 2018).

Ecosystem services

The ecosystem services provided by this site are poorly documented. Given that the majority of the local population are pastoralists, most of the land is utilised as pastureland (Yusuf et al., 2013a). Cordeauxia edulis is a socio-economically important tree, utilised as fodder for livestock and the seeds harvested for market trade at Bokh or Galkayo, just across the border in Somalia. This species, locally known as Yeheb, also has medicinal properties and is used in construction and as fuel, and as a food source in a variety of forms (Alemu et al., 2022).

At least two dry oil wells are known to exist in or around the IPA, one at Galadin (which initially produced oil before being abandoned in the 1950s), and one at Bokh (abandoned June 1965) (Purcell, 1979). Oljira et al. (2020) reported that while the area is now unlikely to contain significant reserves of crude oil, natural gas may be found. There is no known tourism and, due to issues of inaccessibility and security, this is unlikely to change in the near future.

Site assessor(s)

Joe Langley, Royal Botanic Gardens, Kew

Eden House, Royal Botanic Gardens, Kew

Iain Darbyshire, Royal Botanic Gardens, Kew

Sebsebe Demissew, Addis Ababa University

Sileshi Nemomissa, Addis Ababa University

Ermias Lulekal, Addis Ababa University

IPA criterion A species

Species Qualifying sub-criterion ≥ 1% of global population ≥ 5% of national population 1 of 5 best sites nationally Entire global population Socio-economically important Abundance at site
Cordeauxia edulis Hemsl. A(i) True True True False True Frequent
Merremia warderensis Sebsebe A(i) True True True False False Unknown

Cordeauxia edulis Hemsl.

Qualifying sub-criterion:
A(i)
≥ 1% of global population:
True
≥ 5% of national population:
True
1 of 5 best sites nationally:
True
Entire global population:
False
Socio-economically important:
True
Abundance at site:
Frequent

Merremia warderensis Sebsebe

Qualifying sub-criterion:
A(i)
≥ 1% of global population:
True
≥ 5% of national population:
True
1 of 5 best sites nationally:
True
Entire global population:
False
Socio-economically important:
False
Abundance at site:
Unknown

General site habitats

General site habitat Percent coverage Importance
Savanna - Dry Savanna No value Major
Shrubland - Subtropical/Tropical Dry Shrubland No value Major
Grassland - Subtropical/Tropical Dry Lowland Grassland No value Major
Desert - Hot Desert No value Major
Rocky Areas No value Minor
Artificial - Terrestrial - Pastureland No value Major
Artificial - Terrestrial - Urban Areas No value Minor

Savanna - Dry Savanna

Percent coverage:
No value
Importance:
Major

Shrubland - Subtropical/Tropical Dry Shrubland

Percent coverage:
No value
Importance:
Major

Grassland - Subtropical/Tropical Dry Lowland Grassland

Percent coverage:
No value
Importance:
Major

Desert - Hot Desert

Percent coverage:
No value
Importance:
Major

Rocky Areas

Percent coverage:
No value
Importance:
Minor

Artificial - Terrestrial - Pastureland

Percent coverage:
No value
Importance:
Major

Artificial - Terrestrial - Urban Areas

Percent coverage:
No value
Importance:
Minor

Land use types

Land use type Percent coverage Importance
Agriculture (pastoral) No value Major
Harvesting of wild resources No value Major
Residential / urban development No value Minor

Agriculture (pastoral)

Percent coverage:
No value
Importance:
Major

Harvesting of wild resources

Percent coverage:
No value
Importance:
Major

Residential / urban development

Percent coverage:
No value
Importance:
Minor

Threats

Threat Severity Timing
Human intrusions & disturbance - War, civil unrest & military exercises Unknown Past, not likely to return
Agriculture & aquaculture - Livestock farming & ranching - Nomadic grazing High Ongoing - trend unknown
Agriculture & aquaculture - Livestock farming & ranching - Small-holder grazing, ranching or farming High Ongoing - trend unknown
Biological resource use - Gathering terrestrial plants High Ongoing - trend unknown
Climate change & severe weather - Droughts High Ongoing - trend unknown

Human intrusions & disturbance - War, civil unrest & military exercises

Severity:
Unknown
Timing:
Past, not likely to return

Agriculture & aquaculture - Livestock farming & ranching - Nomadic grazing

Severity:
High
Timing:
Ongoing - trend unknown

Agriculture & aquaculture - Livestock farming & ranching - Small-holder grazing, ranching or farming

Severity:
High
Timing:
Ongoing - trend unknown

Biological resource use - Gathering terrestrial plants

Severity:
High
Timing:
Ongoing - trend unknown

Climate change & severe weather - Droughts

Severity:
High
Timing:
Ongoing - trend unknown

Bibliography

White, A.F., 1983

The vegetation of Africa. A descriptive memoir to accompany the UNESCO/AETFAT/UNSO vegetation map of Africa

Friis, I., Sebsebe Demissew, & van Breugel, P., 2010

Atlas of the Potential Vegetation of Ethiopia.

Dioli, M., 2002

Two new species of Pseudolithos P. R. O. Bally (Apocynaceae-Asclepiadoideae) from the Horn of Africa

Kew Bulletin, Vol 57, page(s) 985-988

Friis, I. Gilbert, M.G., Weber, O., & Sebsebe Demissew., 2016

Two distinctive new species of Commicrapus (Nyctaginaceae) from gypsum outcrops in eastern Ethiopia

Kew Bulletin, Vol 72, page(s) 34

Hogg, R., 1991

Famine in the Ogaden

Disasters, Vol 15(3), page(s) 271-273

JICA, 2013

The Study on Jarar Valley and Shebele Sub-basin Water Supply Development Plan, and Emergency Water Supply in the Federal Democratic Republic of Ethiopia. Final Report (2/7), Volume 1: Survey on the potential water resources (groundwater) utilization

Available online

Mabberley, D.J., 2009

Exploring Terra Incognita

Science, Vol 324, page(s) 472

Mohamed, A.E., 2013

Managing shared river basins in the Horn of Africa: Ethiopian planned water projects on the Juba and Shabelle rivers and effects on downstream uses in Somalia

WIT Transactions on Ecology and The Environment, Vol 172, page(s) 139-151

Mohamed, A.E. & Iman, H.M., 2010

‘Hydropolitics in the Horn of Africa: Conflicts and Cooperation in the Juba and Shabelle Rivers.’ in Calas, B. & Martinon, C.A.M. Shared Waters, Sharded Opportunities: Hydropolitics in East Africa

Thulin, M. & Vollesen, K., 2015

Blepharis gypsophila (Acanthaceae), a new species from Ethiopia

Kew Bulletin, Vol 70, page(s) 26

Yusuf, M., Teklehaimanot, Z., & Gurmu, D., 2013

The decline of the Vulnerable yeheb Cordeauxia edulis, an economically important dryland shrub of Ethiopia

Oryx, Vol 47(1), page(s) 54-58

Beech, E., Belay, B., Mekbib, E., Alemu, S., Tesfaye Awas, Bahdon, J., Sebsebe Demissew, Nemomissa, S., Atnafu, H. & Alemu, S., 2018

Cordeauxia edulis. The IUCN Red List of Threatened Species 2018: e.T30386A128447611

Available online

Mège, D., Purcell, P., Pochat, S., & Guidat, T., 2015

‘The Landscape and Landforms of the Ogaden, Southeast Ethiopia.’ In Billi, P. Landscapes and Landforms of Ethiopia

Seyoum, Y. & Mekbib, F., 2014

In vitro germination and direct shoot induction of Yeheb (Cordeauxia edulis Hemsl.)

Agriculture, Forestry and Fisheries, Vol 3(6), page(s) 452-458

Drechsel, P. & Zech, W., 1988

Site Conditions and Nutrient Status of Cordeauxia edulis (Caesalpiniaceae) in its Natural Habitat in Central Somalia

Economic Botany, Vol 42(2), page(s) 242-249

Hemming, C.F., 1966

The vegetation of the northern region of the Somali Republic

Proc. Linn. Soc. Lond., Vol 177(2), page(s) 173-250

Purcell, P.G., 1979

The geology and petroleum potential of the Ogaden basin, Ethiopia. Unpublished Report.

Sebsebe Demissew & Dioli, M., 2000

A new Aloe (Aloaceae) species from Ogaden (Southeastern Ethiopia)

Kew Bulletin, Vol 55, page(s) 679-682

Yusuf, M., Teklehaimanot, Z., & Rayment, M., 2013

Traditional knowledge and practices on utilisation and marketing of Yeheb (Cordeauxia edulis) in Ethiopia

Agroforest Syst, Vol 87, page(s) 599-609

Mekonnen, B., Yahya, A., & Alstrom, S., 2010

Micro-organisms associated with endangered Cordeauxia edulis affect its growth and inhibit pathogens

African Journal of Agricultural Research, Vol 5(24), page(s) 3360-3368

Oljira, T., Nton, M.E., & Sonibare, O.O., 2020

Organic Geochemical Evaluation of Shale Units of Bokh Formation, Ogaden Basin, Ethiopia

Open Journal of Geology, Vol 10, page(s) 565-578

Worku, T. & Astin, T.R., 1992

The Karoo sediments (Late Palaeozoic to Early Jurassic) of the Ogaden Basin, Ethiopia

Sedimentary Geology, Vol 76, page(s) 7-21

Alemu, B., Pu, Z., Debele, G., Goshu, A., Jida, M., Abdikadir, A., Ahmed, A., Dadi, H., Tesfaye, K., Tessema, A. & Chunhong, M., 2022

Proximate analysis of endangered evergreen leguminous shrub Yeheb-nut (Cordeauxia edulis Hemsl.) reveals high content of carbohydrate than protein

Measurement: Food, Vol 7, page(s) 100051

Abubaker, A. et al., 2021

Report to warder field trip in conducting Cordeauxia edulis (Yeheb Plant) Field Survey and Observations

[Unpublished Report]

Sebsebe Demissew, 2001

A Synopsis of the Genus Merremia (Convolvulaceae) in the Flora of Ethiopia and Eritrea

Kew Bulletin, Vol 56(4), page(s) 931-943

Recommended citation

Joe Langley, Eden House, Iain Darbyshire, Sebsebe Demissew, Sileshi Nemomissa, Ermias Lulekal (2024) Tropical Important Plant Areas Explorer: Bokh (Ethiopia). https://tipas.kew.org/site/bokh/ (Accessed on 21/05/2024)