Calanthe caulescens

The drivers of forest change in Papua New Guinea's forests were identified as subsistence agriculture, logging, forest fires, clearance for plantations and mine-related forest clearance (Shearman et al. 2008) and similar threats occur in Indonesian Papua. This orchid has been recorded from within a logging concession area (Sherman et al. 2009) and the process of logging, particularly clear felling, removes the shade that Calanthe species require and they are known to rapidly desiccate and die (Clayton and Cribb 2013). It has been recorded in areas where there is agricultural encroachment into forest, such as in Enga Province, Papua New Guinea, and from areas with mining activity, such as the Grasberg mine, Mt Jaya, Papua, Indonesia. Some areas are subject to threats from fire, for example, in the Mount Giluwe area, where it has been recorded, a massive fire destroyed forest along the Mount Giluwe Range in 1997 (Dudley et al. 1997). The likelihood of fire increases particularly in dry years and droughts associated with El Niño events. Impacts are becoming more frequent and severe and the area of Papua New Guinea's montane forests has been significantly reduced through burning (Shearman et al. 2008). There is a low frequency and diversity of epiphytic plants in many forests known to have been burned (Johns 1989) and the impact of drought itself may also cause decline in orchid populations (E. De Vogel pers. comm. 2017). However, this orchid has a wide geographical extent and nearly 2,000 m elevational range, it is found in several ecoregions and a variety of habitats, including higher montane forests where anthropogenic threats are generally less intense or even absent and much undisturbed montane forest and shrubland remains within its range. In view of this it is suspected that in many areas these threats will not be operational and overall declines small.

This orchid has been recorded within the Lorentz National Park area, a 2.35 million ha protected area, which is the largest in South-East Asia and incorporates a continuous ecological transect from mountain peaks to the coast (UNESCO 2017). It has also been found also close to the c. 8,000 km² Jayawijaya Wildlife Reserve and it may occur within it. The designation of additional protected areas, particularly in Papua New Guinea would be beneficial. It is not known to be conserved ex situ (BGCI 2017). Further studies are needed to give a better understanding of its life history and ecology, and population size and any specific threats. Additional surveys are needed to improve our knowledge of its current distribution.