Back to search results

Tanquana hilmarii

Assessor: Sarah Schumann

Sensitive in 2010
No
Family
Aizoaceae
Reason for the sensitivity status
This species is experiencing ongoing population decline due to harvesting of wild individuals for the specialist succulent horticultural trade. Few known subpopulations 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 Critically Endangered as it is range restricted, known from three fragmented subpopulations and is experiencing ongoing population decline due to harvesting of wild individuals for the specialist succulent horticultural trade (Raimondo 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. This species is sought after by succulent collectors whereby one of its locations has lost uo to 95% f its mature wild individuals to removal and the loss is ongoing  (Raimondo et al. 2007).

Raimondo, D., Schutte-Vlok, A.L. & Vlok, J.H. 2007. Tanquana hilmarii (L.Bolus) H.E.K.Hartmann & Liede. 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 has an extent of occurrence of less than 100 km², is known from three highly fragmented subpopulations whereby one subpopulation has lost up to 95% of its individuals (Raimondo et al. 2007).

Raimondo, D., Schutte-Vlok, A.L. & Vlok, J.H. 2007. Tanquana hilmarii (L.Bolus) H.E.K.Hartmann & Liede. 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

Whole individuals are removed causing population decline and fragmentation (Raimondo et al. 2007).

Raimondo, D., Schutte-Vlok, A.L. & Vlok, J.H. 2007. Tanquana hilmarii (L.Bolus) H.E.K.Hartmann & Liede. 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

Few known subpopulations with existing threat causing population decline makes this species vulnerable to further population loss. Recruitment and recovery from harvesting may be poor. 

Reference file
Tanquana hilmarii Threatened Species Programme _ SANBI Red List of South African Plants.pdf755.32 KB