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Nesohedyotis arborea

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Taxonomy [top]

Kingdom Phylum Class Order Family
PLANTAE TRACHEOPHYTA MAGNOLIOPSIDA RUBIALES RUBIACEAE

Scientific Name: Nesohedyotis arborea
Species Authority: (Roxb.) Bremek.
Common Name(s):
English Dogwood
Taxonomic Notes: Endemic genus of the Hedyotideae, resembling East African genera Hedythyrsus and Pseudonesohedyotis (Tennant 1965), which are small shrubs and not small trees like Nesohedyotis.

Assessment Information [top]

Red List Category & Criteria: Endangered D ver 3.1
Year Published: 2003
Date Assessed: 2003-04-30
Annotations:
Needs updating
Assessor(s): Cairns-Wicks, R.
Reviewer(s): Cronk, Q. & Clubbe, C. (South Atlantic Island Plants Red List Authority)
Justification:
In 1997 the total population size was estimated as about 132. Since then consistent alien plant species control has been carried out as well as the restocking of the endemic trees including Dogwood, these actions are part of the management plan for Diana’s Peak National Park. Between 1996 and 2002 around 4,000 seedlings and cuttings were planted. Survival rates are not known but Dogwood does less well when planted in open ground (cleared of alien plants such as Phormium tenax) than He Cabbage and Whitewood. Until the planted individuals reach sexual maturity the number of mature Dogwoods remains low and fragmented. Few individuals are completely reproductively isolated, as pollen transfer has been shown to be effective up to distances of 50 m (Percy and Cronk 1997). The quality of the habitat at High Peak is deteriorating, potentially threatening the Dogwoods growing there.
History:
1998 Endangered (Oldfield et al. 1998)
1998 Endangered
1997 Endangered (Walter and Gillett 1998)

Geographic Range [top]

Range Description: Within Diana’s Peak National Park the main sites of occurrence are both sides of Diana’s Peak, Mt Actaeon, Cuckhold’s, Jockies and Taylors. It also occurs at High Peak and within a small isolated site on the Sandy Bay Ridge facing Rose Cottage. There was one tree at the Depot.
Countries:
Native:
Saint Helena, Ascension and Tristan da Cunha
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: In 1997 the total population size was estimated as about 132.
Population Trend: Increasing

Habitat and Ecology [top]

Habitat and Ecology: A tree, growing in damp tree-fern thickets on the central ridge 700 m. A good interceptor of mist, water is condensed on the leaves and drops to the ground beneath the tree via a drip-tip. Seedlings are sometimes to be found growing on the trunks of tree-ferns. Main flowering season February – May. The trees exhibit leaky dioecy: females are entirely male-sterile but males can set small amounts of seed. Sex ratio of adult trees 3:2 in favour of males due to greater allocation of resources into vegetative survival (Percy and Cronk 1997). Pollination is by small syrphid flies, including the endemic hoverfly, Loveridgeana beattiei, which is considered an important pollinator for all the cabbage trees on the Peaks. Flowering times are successive (Black Cabbage, Dogwood, Whitewood and Gumwood) possibly avoiding competition for pollinators.
Systems: Terrestrial

Threats [top]

Major Threat(s): Until the planted individuals reach sexual maturity the number of mature Dogwoods remains low and fragmented. The quality of the habitat at High Peak is deteriorating potentially threatening the Dogwoods growing there.

Conservation Actions [top]

Conservation Actions: Protected under the Endangered Endemic and Indigenous Species Protection Ordinance No 7 of 1996. Also protected within the Diana’s Peak National Park which is has been managed under a management plan since 1996 (Smith and Williams 1996). Although its still lacks specific legislation the 1998/1999 revision of the SLUP (1993) provides for the protection of the National Park.

Citation: Cairns-Wicks, R. 2003. Nesohedyotis arborea. The IUCN Red List of Threatened Species. Version 2014.2. <www.iucnredlist.org>. Downloaded on 20 October 2014.
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