A natural hybrid with Dacrydium araucarioides has been described as Dacrydium x suprinii Nimsch. Less than 10 plants have been found.

The extremely small extent of occurrence (36 km²) and single location, coupled with a very small population size (less than 1,000 plants), lack of regeneration as well as recent and projected continuing decline, qualify this species for listing as Critically Endangered.

Confined to a small area around Rivière des Lacs, Lac en Huit, Lac Intermédaire and Grand Lacs in southern New Caledonia. Occurs at 150 to 275 m asl.  In the past it was probably more widespread but has declined due to fires, inundation from reservoirs and hybridisation with Dacrydium araucarioides.

A rare species with a total population of less than 1,000 trees.

A rheophyte growing along the edges of streams in association with Retrophyllum minus, Neocallitropsis pancheri and a range of other flowering plants. It possesses an unusual root anatomy that allows it to withstand high levels of inundation (Carlquist and Nazaire 2016)

The main ongoing threat is fire. In the recent past several subpopulations were lost due to the construction of a dam. At the Chute de 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 10 km upstream may lead to pollution and water stress because of the extraction of minerals. Hybrids with Dacrydium araucarioides have been reported and described (Knopf et al. 2007). This species has become more common in the areas where D. guillaminii occurs.

No uses have been recorded for this species.

This species is legally protected by province Sud and province Nord. One of the largest subpopulation occurs in a protected area (réserve of Chutes de la Madeleine) which is vulnerable to fires. This species is recorded from two ex situ collections (BGCI 2024).

Protecting the wetlands of plaine des Lacs recently recognised by RAMSAR through a management plan would be beneficial to this species.

Monitoring is needed for existing populations and regeneration. It is also necessary to undertake ex situ studies to know how to produce seeds and cultivate plants for future restoration work if it is required.