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ISLAND DIRECTORY

Islands of St Helena (United Kingdom)



St Helena     [917]
   Group:
   Country: United Kingdom - St Helena   Region: South Atlantic
Lat: 15.95º S   Long : 5.72º W
Area: 125.5 sq. km   Altitude: 819 m
Shoreline: 50.1 km (scale 1:1000000)   Coastal Index: 0.3992
Depth to nearest land: 4000 m
Nearest island: 1200 km   group: 1200 km
Nearest continent: Africa    Distance: 1920 km    Isolation Index: 113
ISLAND TYPE: volcanic      Natural Protection Indicator: 0
GEOLOGY/SOILS:
Mountainous volcanic island 14-7 million years old, with high coastal cliffs ca. 300 m, cut by a few steep-sided valleys; heavy acidic clay soils, mountain streams
CLIMATE: dry  subtropical  15-32øC, 152 mm, more in hills
CATASTROPHIC THREATS: drought (1984)
   Threat Indicator: 1
ECOSYSTEMS:           Number of Ecosystems - Terrestrial: 4    Marine: 1
Formerly scrubland and woodland, mostly destroyed by 1650 by heavy grazing; surviving Gumwood woodland at Peak Dale (2 ha), some semi-natural vegetation on central mountain ridge, pasture, abandoned flax plantations, replanted woodland, dry rocky lowland, mountain streams; coastal marine ecosystems
SPECIES NUMBERS: Total Endemic Threatened (EVRI)
Plants  60 50 47
Butterflies 0 0 0
Land snails 6 0 6
Rept/Amphib 0 0 0
Land birds 0 1 1
Mammals 0 0 0

SPECIES OF CONSERVATION INTEREST:
Plants: 60 native and 260 introduced species of flowering plants and ferns 50 endemic species: 7 extinct, 23 Endangered, 17 Rare Pelargonium cotyledonis (RDB) Trochetiopsis (Trochetia) erythroxylon (St Helena Redwood) endemic, less than 10, Endangered Trochetiopsis melanoxylon, endemic, 2 individuals discovered 1980, Endangered Wahlenbergia linifolia, endemic, 5 individuals, Endangered Nesiota elliptica, endemic, i individual, Endangered Psida rotundifolia, endemic, 1 individual, Endangered Commudeudron spurium, endemic, 3 individuals, Endangered Insects: 157 endemic beetles Aplothorax burchelli (Ground Beetle) endemic, Endangered Labidura herculeana (St Helena Earwig) endemic, rediscovered 1965-67, only dead remains found since, Endangered Other invertebrates: 6 molluscs Extinct Reptiles/Amphibians: no terrestrial species Birds: 7 extinct species Charadrius sanctae-helenae (St Helena Wirebird or Plover) endemic, upland habitats at medium elevations, population 200-300 (1986), Rare (RDB) Marine life: 81 shore fishes including 11 endemic
SPECIES RICHNESS:
  Species Richness Indicator - Terrestrial: 0  Marine: 1
poor
ENDEMISM: Terrestrial:   Terrestrial Endemism Indicator - Island: 3  Group: 4
    high
  Marine endemic species: 11   Marine Endemism Indicator - Island: 3  Group: 3
    good
SPECIAL FEATURES :   Special Features Indicator - Terrestrial: 1   Marine: 0
  seabird rookery
INVASIVE SPECIES:     Invasive Species Indicator: 4
  many introduced species

HUMAN OCCUPATION: Inhabited, discovered 1502
  Population: 5499 (1982)   Density: 43.8 persons/sq. km
  Growth Rate: 0.0%/yr   Stable
  Major Human Activities: government, agriculture, fishing
HUMAN IMPACTS:
Vegetation devastated by introduced animals and plants, starting with goats in 16th century; soil badly eroded over 2/3 of island; recent attempts to reintroduce endemic species; former flax and hemp production, now abandoned; livestock grazing
  Accessibility: port, airport
  Percent population in agr/mining/fishing: 20%   Human Threat Indicator: 1
Conservation support: government support, legislation
PROTECTED AREAS:    Protected Area Coverage Indicators - Terrestrial: 0  Marine: 0
  Number: 4   Area: Terrestrial: 0.0 sq. km    Marine: 0 sq. km
Diana's Peak conservation area (nominated for World Heritage) Old Joan Point conservation area High Peak conservation area (nominated for World Heritage) Casons and Hardings National Forest
DATA RELIABILITY:    Data Rel. Indicator: 2
HUMAN IMPACT INDEX     HI: 6
CONSERVATION IMPORTANCE INDEX   CI-Terrestrial: 28   Very high
CI-Marine: 22   High
REFERENCES:
Johnson, Timothy H. 1989. Unpublished ICBP profiles of Atlantic islands.
Last updated: 15/09/90

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Page last updated: 09/05/10