Disa lugens var. nigrescens | SANBI Sensitive Species

Assessor: Juan Swanepoel

Sensitive in 2010

Yes

Family

Orchidaceae

Reason for the sensitivity status

This taxon is declining due to illegal harvesting. Few known locations of occurrence with existing threats causing population decline makes this species vulnerable to further population loss. Recruitment and recovery from harvesting may be poor. Releasing data on this taxon 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 declining due to illegal harvesting and alien plant invasion (von Staden and Liltved, 2012). Other species in this genus are known to be threatened by collection of wild individuals (von Staden et al. 2012).

von Staden, L., Oliver, E.G.H. & Raimondo, D. 2012. Disa longicornu L.f. National Assessment: Red List of South African Plants version 2020.1.

von Staden, L. and Liltved, W.R. 2012. Disa lugens Bolus var. nigrescens (H.P.Linder) H.P.Linder. National Assessment: Red List of South African Plants version 2020.1. Accessed on 2021/12/30

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

The population, known from one location (area of occurrence <5 km²) is declining due to illegal harvesting and alien plant invasion (von Staden and Liltved, 2012).

von Staden, L. and Liltved, W.R. 2012. Disa lugens Bolus var. nigrescens (H.P.Linder) H.P.Linder. National Assessment: Red List of South African Plants version 2020.1. Accessed on 2021/12/30

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.

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

Continued exploitation of mature individuals compounded with ongoing alien plant invasion which has been identified as a threat (von Staden and Liltved, 2012), render the chance of populations recovering to be poor.

von Staden, L. and Liltved, W.R. 2012. Disa lugens Bolus var. nigrescens (H.P.Linder) H.P.Linder. National Assessment: Red List of South African Plants version 2020.1. Accessed on 2021/12/30