Dacrydium guillauminii J.Buchholz

Podocarpaceae

One of four species of Dacrydium endemic to New Caledonia where it has an extremely restricted distribution and is Critically Endangered due to fire, tourism and flooding.

Description

Habit

Shrub to 2.m tall; stem thickened at base, branches wide-spreading and ascending. Bark with horizontal stripes and large lenticles, scaly plates appearing when mature, deep brown; inner bark fibrous, red brown.

Foliage

Leaves of juvenile state only, densely covering branches, narrow and long-pointed, curved forward, triangular in cross-section,13–15 x 1mm, stomata borne in intermittent lines on all sides.

Cones

Male pollen-cones terminal, 8-15 x 4mm, with lateral cones at base. Female seed-cones terminal, 8–10mm long, hidden by leaves. Seeds 1–5 per cone, partially covered by epimatium and subtended by leaf-like bracts and much exceeding the seed; seeds ovoid-oblong, 4–5 x 2.5mm, brown.

Note

A natural hybrid with Dacrydium araucarioides has been described as Dacrydium x suprinii Nimsch (Knopf et al, 2007). Less than 10 plants of this hybrid have been found.

Distribution

Endemic to New Caledonia where it occurs in the southern most part of Province Sud on Grande Terre. Here it is restricted to a small area around Rivière des Lacs, Lac en Huit, Lac Intermédaire and Grand Lacs. The total population is less than 100 mature individuals. In the past it was probably more widespread but has declined due to fires and inundation from reservoirs.

Habitat and Ecology

Occurs alongside streams and lakes in association with the conifers Retrophyllum minus and Neocallitropsis pancheri. Shrubby associated species include Melaleuca brongnartii , Xanthostemon aurantiacum, Homalium kanaliense, Pancheria communis, Cloezia aquarum and herbaecous species include Costularia xyridioides, Schoenus brevifolius, Chorizandra cymbaria, Tricostularia guillauminii, Xyris pancheri and Xyris neocaledonica (Jaffré, 1988). It has an altitudinal range of between 150 to 275m.

Conservation Status

Global assessment

Critically Endangered B1ab(iii,v);C2a(i)

Global rationale

The extremely small extent of occurrence and area of occupancy (12km²) and single location, alongwith a very small population size (less than 100 mature individuals), the lack of regeneration and recent and projected continuing decline, qualify this species for listing as Critically Endangered.

Global threats

The main ongoing threat is fire. In the recent past several subpopulations were lost due to the construction of a dam. At the Chûtes de la Madeleine Reserve, some degradation of its main habitat occurred due to increasing numbers of visitors. A new management plan has reduced their impact. The construction of a new hydro-metallurgical facility 10km upstream may lead to pollution. Hybrids with Dacrydium araucarioides have recently been reported and described (Knopf et al., 2007). This species has become more common in the areas where D. guillaminii occurs.

Conservation Actions

The largest subpopulation occurs at Chûtes de la Madeleine Reserve however this protected area is still vulnerable to fires.