Bowal Tankon and Bowal Touppé Mama

A(i)Site contains one or more globally threatened species, C(iii)Site contains nationally threatened or restricted habitat or vegetation types, AND/OR habitats that have severely declined in extent nationally

Bowal Tankon and Bowal Touppé Mama are home to the last known global populations of Vernonia djalonensis and Emilia djalonensis, endemic species to the Fouta Djallon area of the Guinea highlands. Other historic sites have been searched at Mali and between Timbo and Ditinn, but neither species has been rediscovered in these places. Bowal Tankon is under immediate threat from construction and urbanisation. Based on historical records, three other vulnerable (VU) species are also thought to be present: Kotschya lutea, Eriocaulon sessile, Indigofera megacephala.

Bowal Tankon is southern part of the Diaguissa plateau which runs north east – south west across National Route 5. The plateau is made up of a solid outcrop of iron rich laterite covered by thin soils with some gravel and deeper soils upslope. In the wet season, there is a marsh area on the upper part of the plateau area. Due to it being alongside the road, housing has already sprung up and a new estate area has been marked out and lots assigned. The North West side of the plateau, Bowal Touppé Mama, has a less intact outcrop and has areas which are more gravelly and with deeper soils compared to Bowal Tankon. Both areas have some human influence either from construction, pastoralism or agriculture. The vegetation is typical of the bowal of high altitude and shares affinities with the iron-rich bowal found in the mountains of Guinée Forestière. Areas further north in the Fouta Djallon towards Labé and Pita are not iron rich and therefore have a different composition.

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The Diaguissa plateau is the only known surviving site globally for Vernonia djalonensis CR and Emilia djalonensis CR(PE). There have been recent field campaigns to verify other populations known from old collections, and to search areas that resemble the Diaguissa plateau on satellite imagery. However, these searches have unfortunately not yielded any new or extant populations. The largest part of the population of Vernonia djalonensis is found on the lower slopes of Bowal Tankon with a sparser number found on Bowal Touppé Mama. Emilia djalonensis is known from one Chevalier collection on the Diaguissa plateau of which this is a part. There have been no recent collections of this species. The lower slope of Bowal Tankon is populated with other common bowal species; upslope where there is a temporary marsh in the wet season, there is a large population of Kotschya micrantha, one of only 5 sites known in the Fouta Djallon. On Bowal Touppé Mama, a small sparse population of Mesanthemum tuberosum (VU) has been recorded. Three other vulnerable species, Kotchya lutea, Eriocaulon sessile and Indigofera megacephala have also been recorded from this area. It is conceivable that they are still present, however it is unlikely that Kotschya lutea is still extant here as this species is very distinct and has not been found despite active searching during surveys. It could therefore be locally extinct.

Ferralitic hard pan (impervious). Bowal grassland on a continuous outcrop of concretised iron pan with very thin soils. Different to other bowé in the area as there is very little gravel present.

Major current threats are from 1) Housing (urbanisation): this area has already been marked out for building plots and most plots have been sold (Pers. Comm. Mayor of Dalaba, July 2017). 2) Chinese gravel crushing plant installed after Nov. 2016. Much of the upper slope of Bowal Tankon has been cleared for installation and there was evidence of rubbish burning outside the plant in July 2017 (Pers. Obs. C. Couch).

Martin Cheek, Royal Botanic Gardens Kew

Muhammad Yaya Diallo, Guinee Ecologie

Charlotte Couch, Royal Botanic Gardens Kew