Tropicos | Name - Erica thomensis (Henriq.) Dorr & E.G.H. Oliv.

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Erica thomensis (Henriq.) Dorr & E.G.H. Oliv.

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Project Name Data (Last Modified On 12/8/2019)

Acceptance : Accepted

Taxon Profile (Last Modified On 10/27/2021)

Description: Shrub reaching 3 to 4 m in high

Habitus: Shrub up to 7 m

Phenology: Flowers have been observed in october and november.

Habitat: Gregarious and dominant in the low Erica vegetation belt, which covers only very small areas at the tops of Pico Pequeno and Pico de Sâo Tomé, between 1,900 and 2,020 m in elevation.

Distribution: São Tomé (endemic)

Distribution Note: The species is endemic to São Tomé island and is known from 17 collections made between 1885 (Moller #610, #724) and 2019 (Ikabanga #923, Lachenaud #2868) in São Tomé, near the summit of the Pico de São Tomé and Pico Pequeno.

Case Study: São Tomé

Conservation assessment (Last Modified On 10/27/2021)

Red List Category: Critically Endangered

Status of Conservation Assessment: Submitted to Red List

Date of assessment: 06 May 2021

Assessment rationale: Erica thomensis is a shrub reaching 3 to 4 m in high. It is known from the Erica vegetation belt; between 1,900 and 2,020 m in elevation. The species is known from 17 collections made between 1885 (Moller #610, #724) and 2019 (Ikabanga #923, Lachenaud 2868) in São Tomé, on the Pico de São Tomé and Pico Pequeno. Two collections (Emilio s.n., Henriques #5) have no precise locality and were not considered for this evaluation. These 15 remaining collections represent four occurrences, all of which are situated within the Obô National Park and form one subpopulation. Based on field observation where the species has been collected, we consider none of the occurrences as extirpated. One occurrence is located at the top of Pico Pequeno. The three other occurrences are located around the top of Pico de São Tomé. Based on a 2 x 2 km cell size, the area of occupancy (AOO) of this species is estimated as 8 km², below the upper threshold for “Critically Endangered” status under subcriterion B2. The extent of occurrence (EOO) is calculated as 0.183 km², below the AOO, so we consider the EOO as 8 km², below the upper threshold for “Critically Endangered” status under subcriterion B1. All four occurrences are threatened by an invasive tree species (Cinchona) which has been cultivated in the past and is now regenerating abundantly at the expense of the natural vegetation. The species is dependent on open areas in the forest, which Cinchona is invading. We also consider ecotourism as a future threat that will induce a decline of the extent and the quality of its habitat at Pico de São Tomé. Therefore, these four occurrences represent one location (sensu IUCN, 2019) with regard to the most serious plausible threat (invasive species). Based on the impact caused by the invasive species, we infer a past, present and future continuing decline in its EOO, AOO, the extent and the quality of its habitat number of locations, and the number of mature individuals. E. thomensis is thus assessed as Critically Endangered (CR) B1ab(i,ii,iii,iv,v)+2ab(i,ii,iii,iv,v).

Disclaimer: This assessment was prepared on 6 May 2021. The map proposed below is only based on the specimens available on Tropicos, therefore, may not correspond to the information provided in the assessment rationale.

Conservation measures: The species occurs within Obô National Park. In addition to its characteristic ecology (growing at 1,900-2,020 m in elevation), it is difficult to provide information about conservation actions of E. thomensis. Indeed, monitoring and control of invasive species like Cinchona must be applied. The species should be sought in both Pico de São Tomé and Pico Pequeno where other individuals could occur. This species should be regarded as an HCV1 (High Conservation Value), and as a consequence, it should be included in the management plan within the Obô National Park in which it occurs. It should be included in São Tomé and Príncipe’s list of protected species, and the destruction of its habitat and possible harvesting must, therefore, be limited. Ex situ conservation should be tested, both within São Tomé and internationally. Finally, a public awareness campaign must be conducted involving tourists and other private actors, NGOs, scientific institutions, and the São Tomé and Príncipe government, to ensure that the species is taken into consideration when decisions are made that could impact its conservation.