Dioscorea strydomiana | SANBI Sensitive Species

Assessor: Sarah Schumann

Sensitive in 2010

Family

Dioscoreacea

Reason for the sensitivity status

This species is threatened by the harvesting of its tubers for medicinal purposes as well as being potentially threatened by collection of wild individuals for horticultural trade This genus is in demand and of popular interest in international horticultural trade. A small population size with existing threat causing population decline makes this species highly vulnerable to further population loss. Recruitment and recovery from harvesting may be poor. Releasing data on this species could exacerbate threat and vulnerability.

This species is extremely rare in the wild and is known to be exploited, utilised or traded. The localities of remaining populations need to be protected to avoid any further exploitation, which is likely to drive it to extinction.

Exploitation extent

Significant - wild individuals of the species are known to be exploited, collected, traded or utilized in a targeted manner, and utilisation is widespread, affects the majority of wild populations and/or is causing rapid decline of the wild population.

Justification and references

According to the SANBI Red List Assessment, this species is Critically Endangered as it is known from one location and is experiencing ongoing population decline due to the harvesting of its tubers for medicinal purposes as well as being potentially threatened by collection of wild individuals for horticultural trade (von Staden et al. 2011). This genus is currently in demand and of popular interest in international horticultural trade, as indicated by several online marketplace, e-commerce and auction sites.

von Staden, L., Victor, J.E., Raimondo, D. & Hurter, P.J.H. 2011. Dioscorea strydomiana Wilkin. National Assessment: Red List of South African Plants version 2020.1.

Population vulnerability

Population is vulnerable: size is <= 2500 mature individuals OR the number of known subpopulations is <= 5 OR range is <= 100km² OR species at risk of localised extinctions

Justification and references

This taxon is known from one location, has an estimated population size of 250 plants and has declined by 25% in the past 150 years (von Staden et al. 2011).

von Staden, L., Victor, J.E., Raimondo, D. & Hurter, P.J.H. 2011. Dioscorea strydomiana Wilkin. National Assessment: Red List of South African Plants version 2020.1.

Targeted demographics

Mature (breeding) individuals are killed, significantly weakened or are permanently removed from the wild, OR immature individuals are targeted and this significantly impacts mature (breeding) individuals.

Justification and references

Tubers are harvested causing the death of individuals (von Staden et al. 2011).

von Staden, L., Victor, J.E., Raimondo, D. & Hurter, P.J.H. 2011. Dioscorea strydomiana Wilkin. National Assessment: Red List of South African Plants version 2020.1.

Regeneration potential

This species has a slow population growth rate, or the growth rate varies depending on habitat, and there is a poor chance the wild populations will recover from exploitation OR a collector might feasibly harvest the entire extant population removing the chance of subsequent recruitment.

Justification and references

This species is very slow-growing (von Staden et al. 2011). A small population size with existing threat causing population decline makes this species highly vulnerable to further population loss. Recruitment and recovery from harvesting may be poor.

von Staden, L., Victor, J.E., Raimondo, D. & Hurter, P.J.H. 2011. Dioscorea strydomiana Wilkin. National Assessment: Red List of South African Plants version 2020.1.

Reference file

dioscorea _ eBay.pdf1.04 MB

Dioscorea Aucfan.pdf963.94 KB

Dioscorea Rakuten.pdf507.95 KB

Dioscorea strydomiana Threatened Species Programme _ SANBI Red List of South African Plants.pdf774.14 KB