Tulista marginata

Assessor: Sarah Schumann

Sensitive in 2010
Reason for the sensitivity status
This species and others of the genus are highly targeted and removed from the wild for horticultural and traditional medicine purposes, causing population decline. Subpopulations are morphologically distinct with specific and differentiated ecological preferences making the species more vulnerable to population loss. Regeneration potential is low as subpopulations will not replenish once removed. Releasing data on this species can 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 Endangered as it is known from a small remaining population that is experiencing ongoing population decline due to collecting of wild individuals for the specialist succulent horticultural trade, habitat loss and degradation (Vlok & Raimondo, 2012). This taxon is highly desirable and sought after and has become rare due to over-collecting and other threats (Vlok & Raimondo, 2012). This species and several others of this genus were among those targeted and confiscated from illegal plant collecting (Confiscation Lists (2016-2021) provided by Karoo Desert Botanic Garden, Kirstenbosch Botanical Garden and Cape Nature). This species is thought to be most at risk to over-harvesting as it is highly sought after for horticultural purposes and is highly threatened (Molteno. S, personal communication 2022, 15 June). This suggests that this genus and species is being targeted and that this species is at risk of over-exploitation.

Vlok, J.H. & Raimondo, D. 2012. Tulista marginata (Lam.) G.D.Rowley. 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  3160 km² and is known from 15 subpopulations with an estimated remaining population size of 2500 individuals (Vlok & Raimondo, 2012). There has been a 40% reduction in population in the past two generations with a further 20% expected by 2040 (Vlok & Raimondo, 2012). Subpopulations are disjunct and separated with each subpopulation being morphologically distinct and having specific ecological preferences (Molteno. S, personal communication 2022, 15 June).

Vlok, J.H. & Raimondo, D. 2012. Tulista marginata (Lam.) G.D.Rowley. 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 from the wild causing population decline.

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

A small remaining population, ongoing threats including exploitation causing decline (Vlok & Raimondo, 2012), places the persistence of this species at risk whereby recruitment and recovery may be poor. 

Vlok, J.H. & Raimondo, D. 2012. Tulista marginata (Lam.) G.D.Rowley. National Assessment: Red List of South African Plants version 2020.1.

Low regeneration potential. The plants are slow-growing and long-lived, while the germination rate in habitat is low on average and seedlings have a high mortality rate. Moreover, this species does not form seed banks; the seeds being viable for a year or two at most. 
The seeds are wind-dispersed, but to a very moderate degree, as the seeds generally do not travel more than a few meters from the parent plant. Individual T. marginata subpopulations are all geographically separated to some degree, and all are therefore vulnerable; Should a subpopulation die out or be removed, its chance of being re-established, without human intervention, is effectively zero. An additional issue is that each subpopulation is morphologically distinct, and should be treated as unique.

 (Molteno. S, personal communication 2022, 15 June).