Fiji is home to many species of endangered/endemic flora and fauna. This week we highlight the (Acmopyle sahniana) or Drautabua, as is it commonly known in Fiji. The Drautabua has been previously successfully artificially propagated at the Atlantic Botanic Gardens and was first successfully artificially propagated in Fiji by the Ministry of Forestry at its Colo-i-Suva nursery.
Natural History
Drautabua is one of the Earth’s most primitive plants. Fossil records show that it existed on the ancient Gondwanaland before it broke apart 100 million years ago into Antarctica, South America, and Australia. That was an extremely long time before humans entered the fossil record only 0.25 million years ago. There is nothing on Earth like Fiji’s Amcopyle. Its closest relative lives in New Caledonia (which is also a Gondwanaland relic), but even that one looks very different. Collected as early as 1877 and identified as early as 1920, the Drautabua was not formally described until 1947 (Buchholz and Gray 1947).
Description
The Drautabua has a straight tree trunk, up to 14cm in diameter, and can grow to 8-12m high in the untouched forest. However, in disturbed areas, they only grow up to 4m. Drautabua, the only name recorded for the tree originates from the shape of its leaflets which are like that of a tooth of a whale or tabua. Drautabua trees have few branches and most of them are on the top half of the tree. The leaves are dark green (features as the logo for NatureFiji-MareqetiViti) and have a waxy appearance on the upper surface, and a dry, whitish appearance on the bottom surface. The leaves form two rows on the stem, which rises from the tree trunk. The leaves only grow up to 2.4cm in length, unlike the longer needle-shaped leaves of pine trees. The young leaves are reddish purple in colour. The reproductive structure of the Acmopyle, like other members of its family, is a coneshaped pollen cone. The female cones are fleshy. The seeds have green coloured fleshy receptacles when mature.
Distribution
Today, the Drautabua is just managing to survive, it is known from six small populations on isolated mountain ranges of Viti Levu. The population on Koroyanitu is feared extinct as searches by experienced botanists in the 1990s failed to find it. It is feared that the cyclones of the 1970’s and 80’s which battered Koroyanitu mercilessly were too much for Drautabua there. Another population, perhaps the largest known, is right in the middle of the prospective Namosi opencast copper mine. The original population recorded from Vakarokosiu in Namosi in 1927 continues to survive today.
Habitat Ecology and Behaviour
The Drautabua has a very specific habitat and has only been found in the Upland Rainforest of Viti Levu, at high elevations, along the top of very steep, narrow ridges. Populations have been found at sites located just below the elevation required for Montane Cloud Forests in Fiji. These parts of the forest are usually enveloped by cloud and exposed to strong winds. The Drautabua can survive on soils of low fertility, even on just a small cliffside patch of soil, but are unable to do so at lower elevations.
The tree can mature at around 5-10 years, at a height of 1m. At this age and height, the plant may be able to reproduce if the conditions are favourable. The reproductive cycle of Drautabua is unknown. Studies on this species have revealed that it is a unique member of the Pine family in that it is monoecious, meaning that both male and female cones come from the same tree. In contrast, many members of the same family are dioecious, where male and female cones come from different trees.
However, it has been observed that the two sexes do not occur on the same plant at the same time. They alternate between reproductive seasons. Until the reproductive behaviour of this plant is more intensively studied, we can only assume that it reproduces like other members of the Pine family whereby the pollen is transferred from the male cones to females via the wind. This mechanism of wind pollination probably accounts for the preference of this species to grow on the breezy ridgetops of Viti Levu. While the pollination process has never been observed, the fact that the seeds have a fleshy green receptacle suggests that native frugivorous birds and bats feed on the fruit, thus aiding in the dispersal of this plant to other ridges and other parts of Viti Levu.
Threats
Drautabua may occur in other little researched montane forest areas in Fiji, but its current distribution of just three widely dispersed populations (in six localities) gives us little assurance of its future survival. It is not known if it previously had a wider population distribution on Viti Levu, but the apparent loss of the Mt. Koroyanitu population last recorded in 1947 is indicative of a long-term decline. If a long-term decline is involved, Acmopyle sahniana may be extremely vulnerable to climate change induced changes to the upland microhabitat to which it is currently confined.
Conservation Status
The Drautabua is critically endangered because of its small, declining population and has been
listed as such by the IUCN (2013). Preliminary efforts have been made to search for other populations and to conserve the known populations, as well as try to grow seedlings at lower elevations. No significant success was achieved.
In 2003, just when it seemed that the world’s only viable populations were in the Korobasabasaga range and threatened by the Namosi copper mine development, another three reproducing populations were discovered in the Wabu Forest Reserve during a biodiversity study of the area by the members of the South Pacific Regional Herbarium of the Institute of Applied Sciences of the University of the South Pacific and other environmental non-governmental organisations (NGOs). Since 2003, new populations have been discovered in the Nakorotubu Range forest (2009) and Emalu Forest (2012). The Wabu and Nakorotubu forest sites were within the destructive path of TC Winston in 2016.
These surveys initiated considerable conservation interest, and it is this interest amongst local biologists, NGOs, landowners and government agencies that may result in the eventual conservation action to protect this little-known species. From 2014 to 2016, NatureFijiMareqetiViti and the Ministry of Forests embarked on a campaign to raise the national profile of this species and produced the species recovery plan which recommends the urgent actions needed to save Fiji’s living fossil – the Drautabua.
In recognition of the need to promote its conservation, a Drautabua seedling was planted by the United Nations Secretary-General Antonio Guterres at the Boron House in Suva during his historic visit in 2019.
