Tonkoyah Inselberg Complex

GUITIPA021
Tonkoyah Inselberg Complex

Country: Guinea

Administrative region: Forecariah (Prefecture)

Central co-ordinates: 9.41833 N, 13.23778 W

Area: 6.12km²

Qualifying IPA Criteria

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

IPA assessment rationale

This inselberg complex is the one of the best examples of coastal inselbergs in Guinea and West Africa in general. The inselbergs have significant populations of at four endangered species, including the largest known population of Raphionacme caerulea (EN). They are under threat from quarrying, nomadic cattle grazing and invasive species.

Site description

The Tonkoyah inselberg complex is located in the coastal zone of Forécariah. It is a series of low lying granite shield inselbergs varying in size from c. 1km to 100m. Many of the inselbergs are bordered by mangrove and some have small patches of forest associated with them. In the dry season, the only vegetation is the dehydrated plants of Afrotrilepis pilosa, often forming candelabra structures, and most of the inselbergs are covered with an algal crust. In the wet season these inselbergs are covered with a variety of species and habitats which can be classified into microhabitats (Porembski, 1999) such as temporary pools and wet depressions, the latter dominated by the grass Dilophotiche occidentalis. Some of the inselbergs in this complex also have endangered species present such as Raphionacme caerulea (EN) and Plectranthus linearifolius (EN). In the forest patches associated with some of these inselbergs Stylochaeton pilosus (EN) can be found. Inselbergs in this area are under threat from quarrying for building material. One quarry was started in the area in 2013.

Botanical significance

The microhabitats found on these inselbergs have several threatened species present. The largest inselberg has one of the most significant populations of Raphionacme caerulea and Plectranthus linearifolius; the forest adjacent also has a small population of Stylochaeton pilosus. Other inselbergs in the complex have small populations of Raphionacme and the forest patches adjoining them have populations of Stylochaeton pilosus. One also has a small population of Marsdenia exellii, a rare Apocynaceae liana associated with the vegetation at the interface of inselbergs and forest.

Habitat and geology

Granite shield inselbergs with several different microhabitats present. Areas of seepage and depressions with thin soils, Afrotrilepis pilosus forming clumps, temporary ponds, cracks and crevices, and associated forest patches.

Conservation issues

The main threat to inselbergs in Guinea is from quarrying. There has already been one quarry opened up in the area, this may increase the likelihood of more. The invasive species Breynia disticha was also recorded here in 2012, in small numbers. We have been working with the villagers at Tonkoyah for a number of years and they are aware of the importance of the rare species of plants. They also have issues with nomadic herders coming through and burning the inselberg vegetation and nearby areas for new pasture. This can influence the amount of seed produced and distributed by Raphionacme as the fires are often set in January when the fruits are ripening.

Site assessor(s)

Charlotte Couch, Royal Botanic Gardens Kew

Denise Molmou, Herbier National de Guinee/ Simfer

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
Raphionacme caerulea E.A.Bruce A(i) True True True False False Common
Plectranthus linearifolius (J.K.Morton) B.J.Pollard & A.J.Paton A(i) True True True False False Frequent
Marsdenia exellii C.E.Norman A(i) True True True False False Scarce
Stylochaeton pilosus Bogner A(i) True True True False False Frequent

Raphionacme caerulea E.A.Bruce

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:
Common

Plectranthus linearifolius (J.K.Morton) B.J.Pollard & A.J.Paton

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:
Frequent

Marsdenia exellii C.E.Norman

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:
Scarce

Stylochaeton pilosus Bogner

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:
Frequent

IPA criterion C qualifying habitats

Habitat Qualifying sub-criterion ≥ 5% of national resource ≥ 10% of national resource 1 of 5 best sites nationally Areal coverage at site
Granite Inselbergs C(iii) False True True 6

Granite Inselbergs

Qualifying sub-criterion:
C(iii)
≥ 5% of national resource:
False
≥ 10% of national resource:
True
Areal coverage at site:
6

General site habitats

General site habitat Percent coverage Importance
Rocky Areas - Rocky Areas [e.g. inland cliffs, mountain peaks] No value Minor

Rocky Areas - Rocky Areas [e.g. inland cliffs, mountain peaks]

Percent coverage:
No value
Importance:
Minor

Land use types

Land use type Percent coverage Importance
No use No value

No use

Percent coverage:
No value
Importance:

Threats

Threat Severity Timing
Transportation & service corridors - Roads & railroads Medium Ongoing - stable
Invasive & other problematic species, genes & diseases - Invasive non-native/alien species/diseases - Named species Low Ongoing - increasing
Agriculture & aquaculture - Livestock farming & ranching - Nomadic grazing High Ongoing - increasing
Energy production & mining - Mining & quarrying High Future - inferred threat

Transportation & service corridors - Roads & railroads

Severity:
Medium
Timing:
Ongoing - stable

Invasive & other problematic species, genes & diseases - Invasive non-native/alien species/diseases - Named species

Severity:
Low
Timing:
Ongoing - increasing

Agriculture & aquaculture - Livestock farming & ranching - Nomadic grazing

Severity:
High
Timing:
Ongoing - increasing

Energy production & mining - Mining & quarrying

Severity:
High
Timing:
Future - inferred threat

Management type

Management type Description Year started Year finished
No management plan in place No value No value

No management plan in place

Year started:
No value
Year finished:
No value

Bibliography

Lisowski, S., 2009

Flore (Angiospermes) de la République de Guinée.

Couch, C., Magassouba, S., Rokni, S. & Cheek, M., 2018

Threatened plants species of Guinea-Conakry: A preliminary checklist

Peerj Preprints

IUCN, 2019

IUCN Red List

Available online

Recommended citation

Charlotte Couch, Denise Molmou (2024) Tropical Important Plant Areas Explorer: Tonkoyah Inselberg Complex (Guinea). https://tipas.kew.org/site/tonkoyah-inselberg-complex/ (Accessed on 21/05/2024)