Diospyros (Diospyros impolita)
Diospyros impolita is classified as Vulnerable (VU) on the IUCN Red List (1).
Diospyros impolita is a rather poorly known tree species found only on the island of New Caledonia, in the southwest Pacific (1). It belongs to the Ebenaceae family, a group of small trees and shrubs which includes the ebonies and persimmons. Little information is available on Diospyros impolita, but like other members of this group it is likely to be characterised by having black bark, roots and heartwood (2) (3). Most Diospyros species grow as small- to medium-sized trees of the forest understory (3).
The leaves of Diospyros species are alternate and have smooth margins. The male flowers usually grow in small clusters, known as inflorescences, which arise from the leaf axils (the points where the leaves meet the stem of the plant). The female flowers are generally larger and slightly different in shape to the male flowers, and usually grow alone (2) (3).
In most Diospyros species, the flowers are articulated at the base and are regular in shape. The petals are commonly fused into a tube, usually with three to eight contorted lobes at the tip (2) (3). Like other members of the Ebenaceae family, Diospyros impolita probably has white, cream or pinkish flowers (2).
Diospyros impolita is endemic to New Caledonia, where it is known only from dry forests between Bourail and Poya, on the west coast of the island. The total area occupied by this species is estimated at just 52 square kilometres (1).
Found mostly on calcareous and other sedimentary soils (4) (5), Diospyros impolita occurs in dry forests below elevations of about 300 metres (1) (4). Also known as ‘sclerophyll forests’, the dry forests of New Caledonia usually consist of relatively dense trees of about 9 to 12 metres in height, and have a thick understory of shrubs and grasses (6).
Little information is available on the specific biology of Diospyros impolita. However, like other Diospyros species it is likely to have separate male and female flowers, which are usually borne on separate plants (2) (3). The flowers are probably pollinated by insects (3).
The fruit of Diospyros species is a berry, which may contain between 1 and 16 seeds. The fruits and seeds of these species are typically dispersed by birds or mammals, but the fruits have a very astringent taste until they are ripe (2) (3).
Diospyros impolitais known from just eight locations within its restricted range (1). The dry forests in which this species occurs are one of the most threatened tropical dry forest habitats in the world (1) (6) (7), having been reduced to just one or two percent of their original extent (1) (8). The forest that does remain is highly fragmented, and often degraded (1) (7) (9).
One of the main threats to New Caledonia’s dry forests is clearance for agriculture and cattle grazing. Grazing and trampling by cattle and other introduced species, such as pigs and the Javan rusa (Rusa timorensis), has also degraded the forest and prevented it from regenerating (1) (6) (8) (9). The Javan rusa, or rusa deer, also damages trees by rubbing its antlers against them (1).
A further threat to New Caledonia’s dry forests, and to populations of Diospyros impolita, comes from uncontrolled fires which sweep across the lowlands each year during the dry season (1) (6) (7) (8). These fires are likely to become more frequent and severe due to climate change, which may also cause repeated periods of drought (8). Nickel mining has also caused widespread deforestation and erosion on New Caledonia (7) (8).
New Caledonia is recognised as a global ‘hotspot’ of biodiversity (7). Around 75 percent of the island’s plants are found nowhere else (4) (7) (8) (9), and the dry forests alone contain 59 endemic plant species, including Diospyros impolita (9). Although this unique habitat remains largely unprotected (4) (7) (9), Diospyros impolita is reported to occur in two protected areas (1).
General conservation measures recommended for New Caledonia include expanding and improving the protected area network, controlling introduced species, undertaking habitat restoration, controlling and limiting forest fires, and introducing strict mining regulations (4) (6) (7) (9). Organisations such as Conservation International and WWF are working to address some of these issues, as well as to raise public awareness of the unique dry forest habitat (6) (10).
Find out more about conservation on New Caledonia:
Conservation International: Biodiversity Hotspots - New Caledonia:
WWF - New Caledonia Dry Forests:
Secretariat of the Pacific Regional Environment Programme - New Caledonia:
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- Alternate leaves: leaves that are located at alternating points along a stem, rather than in opposite pairs.
- Calcareous: containing calcium carbonate, chalky.
- Endemic: a species or taxonomic group that is only found in one particular country or geographic area.
- Heartwood: the inner layers of wood in a tree that no longer contain living cells or produce sap. Heartwood tends to be darker in colour than the outer ‘sapwood’.
- Inflorescence: the reproductive shoot of a plant, which bears a group or cluster of flowers.
- Pollination: the transfer of pollen grains from the stamen (male part of a flower) to the stigma (female part of a flower) of a flowering plant. This usually leads to fertilisation, the development of seeds and, eventually, a new plant.
- Sclerophyll: a type of vegetation with hard, thick-skinned leaves; for example, eucalypts and acacias.
IUCN Red List (May, 2011)
- Heywood, V.H. (1978) Flowering Plants of the World. Oxford University Press, Oxford.
- Kubitzki, K. (Ed.) (2004) The Families and Genera of Vascular Plants. Volume VI: Flowering Plants. Dicotyledons: Celastrales, Oxalidales, Rosales, Cornales, Ericales. Springer-Verlag, Berlin and Heidelberg.
- Jaffré, T., Bouchet, P. and Veillon, J.M. (1998) Threatened plants of New Caledonia: is the system of protected areas adequate? Biodiversity and Conservation, 7: 109-135.
- Morat, P., Jaffré, T. and Veillon, J.M. (2001) The flora of New Caledonia’s calcareous substrates. Adansonia, 23(1): 109-127.
WWF - New Caledonia Dry Forests (May, 2011)
Conservation International: Biodiversity Hotspots - New Caledonia (May, 2011)
Secretariat of the Pacific Regional Environment Programme - New Caledonia (May, 2011)
- Bouchet, P., Jaffré, T. and Veillon, J.M. (1995) Plant extinction in New Caledonia: protection of sclerophyll forests urgently needed. Biodiversity and Conservation, 4: 415-428.
Conservation International - New Caledonia (May, 2011)