Dacrydium nidulum (chawènum) description

Conservation Status

Dacrydium nidulum

de Laub. (1969)

Common names

New Guinea: chawènum, kasuari, kwennum [Arfak, Maibrat language], tjikwal [Hattam], jammari [Wandammen], samiampi [Japen, Roberbai dialect], kun [Eipomek valley, Irian language], ibaro [Upper Waria], binban [Oriomo], nidjon [Kebar valley], nipaj [Arfak, Karoon language], uier [west of Hollandia, Itik language] (de Laubenfels 1988), yaka.

Taxonomic notes

Type: Indonesia, Papua, Jazirah Doberai, Ayamaru Lakes, NW side of lake, 1962.03.10, W. Vink & M. Vink BW 15271 (holotype L0050815). Syn. Corneria nidula (de Laub.) A.V.Bobrov & Melikyan; Dacrydium nidulum var. vitiensis Silba. The phylogenetic position is uncertain; see Dacrydium for discussion. Although both D. nausoriense and D. nidulum are native to Fiji and seem to be fairly closely related, still there is no molecular evidence of hybridization or introgression between the two species (Keppel et al. 2011).

De Laubenfels (1969) described Dacrydium nidulum var. araucarioides but subsequently (de Laubenfels 1988) assigned the variety to a new species, D. cornwallianum.

Description

"Tree 10 to 30 m tall, 18-50 cm diam., with numerous branchlets forming a dense crown. Juvenile leaves up to 2 cm long, slightly curved forward, acute, triangular in cross section, 0.2 mm wide and less thick. Adult leaves not crowded (leaf tips distant from adjacent leaves), nearly straight to distinctly curved so that the apex is parallel with the shoot, abruptly acute to blunt, often apiculate, 1-5 mm long but mostly 2-3.5 mm, triangular in cross section, strongly keeled on the back, 0.3-0.7 mm wide and 0.2-0.3 mm thick. Fertile structures terminal but pollen cones may also be lateral. Pollen cones 8-18 mm long and 1-1.6 mm diam. Microsporophylls 0.8-1.2 mm long. Seed-bearing structure subtended by leaves distinctly shorter than normal foliage leaves, as short as 1.5 mm; cone bracts increasing towards the apex where one or two may be fertile, up to 4 mm long and completely surrounding the epimatium but surpassed by the apex of the mature seed which is 3.5-4 mm long and glossy brown" (de Laubenfels 1988).

"There is some variation between the different widely distributed populations. In the Cycloop Mts and in Fiji the leaves are not apiculate and, particularly in Fiji, the leaves arc nearly straight. Variations in length seem to be mainly a function of age or exposure, with younger and protected plants tending to have longer leaves" (de Laubenfels 1988).

Distribution and Ecology

Fiji, Indonesia (Sulawesi, North Maluku, New Guinea), Papua New Guinea (incl. Sudest Island), Solomon Islands. Occurs at elevations of 0-1200 m but mostly below 600 m (de Laubenfels 1988). Within its range, mean annual temperature is 21.1°C, with an average minimum in the coldest month of 16.1°C, and a mean annual precipitation of 2803 mm (Biffin et al. 2011). It is usually found as a canopy tree in lowland tropical rainforest, often associated with swampy areas, river banks and lake shores (Thomas 2013).

Distribution data for all species, from GBIF Occurrence Download https://doi.org/10.15468/dl.yvmru2 accessed 2025.12.08. D. nidulum color is orange. Click on any point for more info.

The ecology of D. nidulum in Fiji (NE of Vanua Levu) was studied by Keppel et al. (2006), who call the are "Fiji’s last major system of mesic forest." The area has an elevation of 0-100(-200) m and a very uniform average annual temperature of 26°C, with annual precipitation of 1750–2250 mm. The dominant vegetation is a "mesic forest" community that includes two distinct forest types where D. nidulum is a dominant species. In the mesic ridge forest, tree vegetation is dominated by D. nidulum, Gymnostoma vitiense, and Fagraea gracilepes, which occur in different proportions at different locations. There is also a significant component of Agathis macrophylla. They also describe a "stunted Dacrydium nidulum forest" which is a form of mesic forest in which D. nidulum forms low-growing, monodominant stands. In some places only a few sedges or no vegetation at all persist. Monodominant stands such as this are rare in the tropics and can be caused by nutrient-poor soils or compounds impairing plant growth (Richards 1996). The area also supports a relatively rare, previously undescribed freshwater and brackish wetlands covered by a stunted forest dominated by D. nidulum.

The site on Vanua Levu is unique. Palynological evidence indicates this forest type was probably widespread on Viti Levu and Vanua Levu prior to human settlement (Southern 1986) but has been reduced to small remnant pockets and may now be entirely gone from Viti Levu. The surviving forest in NE Vanua Levu is the last extensive stand of this vegetation type remaining in Fiji. Logging is the single largest threat to this forest system. Logging would damage the forest almost irreversibly, with recovery taking at least several centuries. Other threats are invasive plant species, with the raintrees Albizia lebbeck and Samanea saman and the African tulip tree Spathodea campanulata as the primary threats (Keppel et al. 2006). In spite of this, the most recent IUCN conservation assessment (2011) assessed Dacrydium nidulum as of "Least Concern" for conservation due to its wide distribution.

D. nidulum in New Guinea forms almost pure stands (>95% of all trees) on swampy land in the Western and Southern Highlands. These are low-productivity ecosystems due to flooding, drought stress and low nutrient availability (Enright and Jaffré 2011). Podocarp success on such wetland soils may be due to their arbuscular mycorrhizae, which better tolerate saturated soils with low oxygen content when compared to the ectomycorrhizae that predominate in drier forest ecosystems (Khan 2004).

In 2011 the IUCN assessed the conservation status of this species as "Least Concern" because it has a wide distribution; however it is likely undergoing a reduction in its area of occupancy due to general deforestation and habitat conversion.

Remarkable Specimens

Ethnobotany

D. nidulum is highly valued as a source of construction lumber in Fiji and some other areas (Thomas 2013).

Observations

No data as of 2026-07-31.

Remarks

The epithet is from the Latin nidus, "nest", referring to how the growing seed cone is "nested" within elongated leaf-like bracts.

Citations

Biffin, Ed, Timothy J. Brodribb, Robert S. Hill, Philip Thomas and Andrew J. Lowe. 2011. Leaf evolution in Southern Hemisphere conifers tracks the angiosperm ecological radiation. Proceedings of the Royal Society B, doi.org/10.1098/rspb.2011.0559. Data from Table S5.

de Laubenfels, D. J. 1969. A revision of the Malesian and Pacific rainforest conifers, I. Podocarpaceae, in part. Journal of the Arnold Arboretum 50:292-295. Available: Biodiversity Heritage Library, accessed 2025.12.14.

de Laubenfels, David J. 1988. Coniferales. P. 337-453 in Flora Malesiana, Series I, Vol. 10. Dordrecht: Kluwer Academic. Available: Biodiversity Heritage Library, accessed 2025.12.11.

Enright, N. J., and T. Jaffré. 2011. Ecology and distribution of the Malesian podocarps. Pp. 57-77 in B. L. Turner and L. A. Cernusak (eds.), Ecology of the Podocarpaceae in Tropical Forests. Smithsonian Contributions to Botany no. 95. Smithsonian Institution, Washington, DC.

Keppel, G., I. A. Rounds, and N. T. Thomas. 2006. The flora, vegetation, and conservation value of mesic forest at Dogotuki, Vanua Levu, Fiji Islands. New Zealand Journal of Botany 44:273–292.

Keppel, G., P. Prentis, E. Biffin, et al. 2011. Diversification history and hybridisation of Dacrydium (Podocarpaceae) in remote Oceania. Australian Journal of Botany 59:262-273. doi.org/10.1071/BT10181

Khan, A. G. 2004. Mycotrophy and its significance in wetland ecology and wetland management. Pp. 95-114 in Wetlands Ecosystems in Asia. Elsevier.

Richards, P. W. 1996. The tropical rain forest. Cambridge, UK: Cambridge University Press.

Southern, W. 1986. The Late Quaternary environmental history of Fiji. PhD thesis, Australian National University, Canberra.

Thomas, P. 2013. Dacrydium nidulum. The IUCN Red List of Threatened Species 2013: e.T42471A2981334. dx.doi.org/10.2305/IUCN.UK.2013-1.RLTS.T42471A2981334.en, accessed on 2025.12.20.