Dioscorea sylvatica | SANBI Sensitive Species

Assessor: Sarah Schumann

Sensitive in 2010

Family

Dioscoreacea

Reason for the sensitivity status

This species was known to be heavily exploited in the past for commercial medicinal production and currently continues to be utilized in local medicinal plant 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 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 Vulnerable as it was heavily exploited in the past for commercial medicinal production and currently continues to be utilized in local medicinal plant trade (Williams et al. 2008; Dold & Cocks, 2002; Williams et al. 2007). 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.

Dold, A.P. and Cocks, M.L. 2002. The trade in medicinal plants in the Eastern Cape Province, South Africa. South African Journal of Science 98:589-597.

Williams, V.L., Witkowski, T.F. and Balkwill, K. 2007. Volume and financial value of species traded in the medicinal plant markets of Gauteng, South Africa. International Journal of Sustainable Development & World Ecology 14(6):584-603

Williams, V.L., Raimondo, D., Crouch, N.R., Cunningham, A.B., Scott-Shaw, C.R., Lötter, M. & Ngwenya, A.M. 2008. Dioscorea sylvatica Eckl. 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 species has declined by more than 30% in three generations (90 years), it is rare in the wild, subpopulations tend to be smaller than in the past and ongoing harvesting is suppressing the population (Williams et al. 2008).

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

Whole tubers are harvested (Williams et al. 2008).

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 slow growing and ongoing pressure from trade is limiting the recovery of this species (Williams et al. 2008).

Reference file

Dioscorea sylvatica Threatened Species Programme _ SANBI Red List of South African Plants.pdf584.4 KB

dioscorea _ eBay.pdf1.04 MB

Dioscorea Aucfan.pdf963.94 KB

Dioscorea Rakuten.pdf507.95 KB