Dioscorea deltoidea

The main threat experienced by this species has been overharvesting from the wild for its rhizomes and leaves, which are used medicinally. There are estimated declines of up to 80% in India and population declines have also been reported for Nepal and Pakistan. Current data suggests that the rate of wild harvesting of this species has been declining, though the cause of this is unclear and may be multifaceted. The cultivation of alternative sources of the medicinal compound found in this species, a general reduction in demand or the increased scarcity of the species in the wild are all possible causes of the decline in wild harvesting. Current evidence suggests that undocumented trade between Nepal and India, which once exceeded several hundred tons per year is now less than ten tons per year. This trade is suspected to still be ongoing, though is possibly decreasing in scale (Mulliken and Crofton 2008). This suggests that harvesting for international and national trade in this species is still an ongoing threat to this species, but whether it is still occurring on a scale large enough to have a significant impact on populations is unclear, and it is probably still harvested on a small scale for local use in some areas. However, more research on this is very much needed due to a high level of uncertainty on both the scale of harvesting and the impact it is having on populations.

The main current threat to this species is therefore likely to be the continued loss and degradation of its natural habitat. In the Himalayas biodiversity hotspot where this species is primarily found, there is a growing human population which has resulted in extensive forest clearing for agriculture, logging, fuelwood harvesting and livestock grazing. Large areas of habitat within the hotspot have been highly degraded. Only around 25% of the original vegetation in the hotspot still remains today (Arisdason and Mao 2021) and it is likely that this will have impacted this species in different parts of its range.

This species has been recorded from several protected areas (UNEP-WCMC and IUCN 2023). It is also listed as threatened on several national Red Lists (Semwal et al. 2021). This species is listed in CITES Appendix II, but three range countries (Afghanistan, Lao PDR and India) have imposed stricter domestic measures prohibiting exports.