Scientific Name: Dryopteris ascensionis
Species Authority: (Hook.) Kuntze
Taxonomic Notes: Very close to Dryopteris cognata, which is considered to be endemic to St. Helena. Further examination of material is necessary to establish the true relationship between these species.
Assessment Information [top]
Red List Category & Criteria: Extinct ver 3.1
Year Published: 2012
Assessor/s: Lambdon, P.W., Stroud, S., Gray, A., Nissalo, M. & Renshaw, O.
Reviewer/s: Hilton-Taylor, C. & Scott, J.A.
Justification:
This species was listed as Extinct in 2003. Despite regular searches of all suitable areas since then, no further plants have been located.
History:
2003 – Extinct
1997 – Extinct/Endangered (Walter and Gillett 1998)
Geographic Range [top]
Range Description: This species was probably once a component of the “carpet of ferns” which Joseph Hooker described as covering the summit of Green Mountain on Ascension Island, following his visit in 1843. It has not been observed since 1889, although a potential sighting was reported in 1976 near Garden Cottage. When the location was revisited a year later, no trace could be found, and the area is now heavily overgrown with smothering vegetation (Cronk 1980).
Range Map: Click here to open the map viewer and explore range.
Population [top]
Population: This species is extinct.
Habitat and Ecology [top]
Habitat and Ecology: From collected specimens, it appears that the species was a fairly small Dryopteris, and was probably adapted to grow in low fern swards in exposed places, probably above 700 m. Due to the density of tall, vigorous invasive species now present on Green Mountain, it seems unlikely that any suitable habitat now remains. The only remaining chances of persistence are on inaccessible rocky outcrops. However, the chances of rediscovery seem remote.
Systems: Terrestrial
Threats [top]
Major Threat(s): From the 1860s onward, a large-scale vegetation programme was commenced on Green Mountain, initiated by Joseph Hooker, with the aim of improving soil structure, water retention and mist interception, and thus enhancing the productivity of the island for the recently established British naval colony. As part of this programme, large areas of fern sward near the summit were destroyed, and over 200 species of non-native trees, shrubs and herbs planted over the slopes. Many of these species were subsequently naturalized. The extensive habitat modifications have almost certainly been the major cause of decline of rare montane endemics such as D. ascensionis. The numerous invasive species have continued to spread, and now occupy almost all the vegetated habitat on the mountain.
Conservation Actions [top]
Conservation Actions: Green Mountain was declared a National Park in 1996. Due to the low population density on Ascension, there is little human interference in the area and further legislation is not a priority.
The Island’s Conservation Department conduct an annual survey of endemic plant numbers in which suitable areas of Green Mountain are searched. In addition, many remote areas may be visited as part of routine maintenance activities. These efforts have failed to locate any populations thus far.
www.iucnredlist.org/apps/redlist/details/43920/0
