Justification
This long-lived species with a generation length of between 30 and 50 years is endemic to Namibia and known from only the northern Tsau //Khaeb Sperrgebiet National Park where it is restricted to Bushman candle plain dwarf shrubland and Salsola dwarf shrubland vegetation zones. It has an extent of occurrence (EOO) of 571 km2 and area of occupancy (AOO) of 168 km2. The species is found in 2–5 locations while the population is currently stable it is predicted to decline by more than 50 % over the next 100 years. The entire range falls within the proposed development footprint for the green hydrogen projects for the Southern Corridor Development Initiative and while planning efforts are being made to avoid impact to this species, the necessary construction of an extensive road and powerline network required to reach wind turbines, solar plants and processing facilities means that there will be significant destabilization of highly sensitive ecosystems and this will lead to ongoing degradation and eventual habitat loss for this species. It is therefore listed as Endangered under criterion A3.
Geographic Range Information
The species is endemic to southwestern Namibia, restricted to the northwestern parts of the Tsau //Khaeb Sperrgebiet National Park (TKNP). It was originally found in two distinct localities (Van Wyk et al. 2010), one in the southeastern part of a large, shallow draining area of the ephemeral Kaukausib River and surrounding the Kaukausib fountain, the second occurs west on a gently undulating area of gneiss ridges. Field work carried out in September and October 2023 revealed further localities between the two original subpopulations and another one further northeast on the Rotkup to Grillenthal Road.
Population Information
The population consists of nine subpopulations each varying in size. A total of 10,158 mature plants were counted in an initial survey in September–November 2023. Some subpopulations are very densely populated and some very sparsely. Since the furthest lying areas could not be surveyed on foot, it is quite possible that additional stands of plants are present towards the centre of the distribution range. An upper estimate of the population size is projected to be 12,500 mature individuals. While the population is currently stable it is projected to experience a decline of 50% of the population within the next 100 years as a result of the construction of renewable energy infrastructure to support the green hydrogen projects for the Southern Corridor Development Initiative.
Habitat and Ecology Information
This long lived species occurs on foot-slopes and plains surrounding ridges. The vegetation is classified as Bushman candle plain dwarf shrubland and Caroxylon dwarf shrubland. Some associated species include Monsonia patersonii (Geraniaceae), Caroxylon species (Amaranthaceae) and Stipagrostis ciliata (Poaceae) (Van Wyk et al. 2009).The soils at both localities are poorly developed eutric regosols (Van Wyk et al. 2009). Plants are more abundant on south and southwest-facing slopes but are found on all slope aspects.
Threats Information
Currently, green hydrogen projects for the Southern Corridor Development Initiative pose the most serious threat to this species in the form of initial habitat destruction, specifically the construction of a wind farm consisting of approximately 600 wind turbines in the next 10 years. While efforts are being made to avoid the plants in the current planning phase and preliminary EIA work, it is likely that there will still be damage to the populations during the construction phase as a result of non compliance to the Environmental Management Plan. Furthermore once the turbines are operational, they have to be maintained, and experience shows that this will cause a further continuous decline in the quality of the habitat as a result of ongoing slow disturbance of habitat. The subpopulation on the Rotkuppe road has its highest density right next to one of the main routes that run through the park in a north-south direction. The plants are at risk of direct damage by off-road driving, road construction and maintenance. Traffic on this route is bound to increase significantly once the windfarm is constructed because it is already used for tourism as well as to access the NAMDEB diamond mines. The most significant damage is likely to come from destabilization of vegetation as a result of construction that leads to large scale movement of sand and burying of plants.
The effects of climate change may be a potential future additional threat as the Sperrgebiet region has already experienced a severe extended drought between 2015 and 2022, and future aridification and increases in temperature are predicted by climate models. While this species has not yet been impacted by the drought, and field observations made after a season of good rains in 2023 indicated that the plants were in good condition, other long-lived species in the region have recently showed rapid population declines in response to climate change and hence this remains a potential threat to this species also.
Use and Trade Information
Conservation Actions Information
The entire population of this species falls within a formally protected area. Public access to this park is more restricted than any other national park. However, a large scale Green Hydrogen and associated renewable energy developments is planned in this park in the area overlapping the species distribution. There is reported to be one ex situ collection (BGCI 2024).