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Ixora margaretae 

Scope: Global
Language: English
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Taxonomy [top]

Kingdom Phylum Class Order Family
Plantae Tracheophyta Magnoliopsida Rubiales Rubiaceae

Scientific Name: Ixora margaretae (N. Hallé) Mouly & B. Bremer
Synonym(s):
Captaincookia margaretae N. Hallé
Taxonomic Notes: This species is valid, however a revision of the genus is under discussion.

Assessment Information [top]

Red List Category & Criteria: Vulnerable A2ce; B1ab(iii)+2ab(iii) ver 3.1
Year Published: 2010
Date Assessed: 2007-05-15
Assessor(s): Hequet, V.
Reviewer(s): Pollock, C.M. & Hilton-Taylor, C.
Justification:
Ixora margaretae has an extent of occurrence (EOO) of 2,869 km2 and an area of occupancy (AOO) of 40 km2. The species is endemic to New Caledonia, where it is known from six locations. It is mostly found in dry forests, a habitat that is among the most threatened in New Caledonia. Dry forests have been reduced dramatically, both in size and quality. They have been severely cleared for agricultural purposes over the last century and what remains today are highly fragmented patches that suffer intense predation by introduced Rusa Deer (Rusa timorensis). The reduction of dry forest has been estimated at 95% over the last 150 years (Bouchet 1995) and this degradation continues today. From this it is suspected that a population reduction of at least 30% has occurred over this time period; the actual generation length for this species is not known, but with evidence of dramatic declines in dry forest habitat it is likely that there has been a population reduction of at least 30% over the last three generations.
Previously published Red List assessments:

Geographic Range [top]

Range Description:This species is endemic to New Caledonia. It occurs in scattered subpopulations from Poya to Kone with a large subpopulation within the fenced reserve of Nekoro. Distances between occupied sites are (respectively and from south to north) 16, 25 and 17 km. Its total extent of occurrence is 2,869 km2 and its estimated area of occupancy within this range is 40 km2.
Countries occurrence:
Native:
New Caledonia
Additional data:
Estimated area of occupancy (AOO) - km2:40
Number of Locations:6
Upper elevation limit (metres):300
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:Population size is unknown. Where present, this species usually occurs as small groups of 5–10 clones. The Nekoro site holds a large subpopulation of more than a hundred individuals; the species is more discreet on the other sites. A recent genetic study suggests that Nekoro holds two distinct subpopulations, one being close to the Pindai subpopulation, and the other close to the Tiéa subpopulation. This study also shows that the genetic diversity is good and that the size of the population should be sufficient to maintain diversity if all the subpopulations are maintained.
Current Population Trend:Unknown
Additional data:
Population severely fragmented:No

Habitat and Ecology [top]

Habitat and Ecology:This species is actually being taxonomically revised. It has mostly been found in dry forests but some specimens have been recently collected in mesic forests. Studies will show whether all specimens belong to the same species. Tropical dry forests are probably among the world’s most endangered of all lowland tropical forests. Because of their propensity to become pastures and their susceptibility to fire, dry forests have reduced dramatically, in size as well as in quality. In New Caledonia, they’ve been intensively cut for agricultural purposes for a century; what remains today are highly fragmented patches that have been estimated at 2% of the original area.
Systems:Terrestrial
Continuing decline in area, extent and/or quality of habitat:Yes

Threats [top]

Major Threat(s): The major threat is lowland clearing for cattle grazing and agriculture, which began in the 1850s and is ongoing. Another threat comes from the Rusa Deer (Rusa timorensis), which was introduced in the 1880s and adapted extremely well to the Caledonian habitats. Its population may have reached 105,000–110,000 individuals in the wild. This deer consumes a wide variety of plant species and also causes severe damage to trees by rubbing antlers against tree stems. The third major threat is uncontrolled fires that sweep across lowlands of New Caledonia each year during the dry season and have slowly transformed remnant patches of dry forest into shrubland dominated by Acacia spirorbis and Leucaena leucocephala, or Niaouli (Melaleuca quinquenervia) savannas. In one of the subpopulations (Tiéa), it has been shown that Ixora margaretae fruit production was suffering from rat predation (Rattus rattus and Rattus esculans).

Conservation Actions [top]

Conservation Actions: This species is present in three protected areas. It has been grown from seeds and 28 plants have been used in a restoration program in the Parc Zoologique Forestier (Nouméa).

Citation: Hequet, V. 2010. Ixora margaretae. The IUCN Red List of Threatened Species 2010: e.T31141A9608910. . Downloaded on 21 November 2017.
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