Aloidendron ramosissimum

The majority of the Richtersveld subpopulations are considered to be in ill-health with between 70% and 100% mortality on foot slopes of mountains due to the extreme nature of the drought that started in 2016 and is still ongoing at the time of assessment. There has been little to no recruitment occurring, even after some areas received relief in the form of over 200 mm of rain (P. van Wyk pers. comm. 2022). Subpopulations that have been observed to have declined severely include the stands on the lower slopes of Hellskloof (69%), Halfmense Pass (97% decline) and Remhoogte (100% decline). Evidence of these declines have been documented on the iNaturalist platform see for example https://www.inaturalist.org/observations/91941966.

Reports from the Spitskop farm locality, northwest of the Richtersveld suggest that there the impacts of the recent drought are not as severe with the adult life stage displaying healthy signs (e.g. flowering and lower desiccation levels) (P. Jacobs pers. comm. 2020). Furthermore, on the upper slopes of the Vandersterrberg mountains in the Southern Richtersveld the subpopulation is still stable.

Based on these observations the overall population is inferred to have declined by between 30 and 40% since 2016. Decline is expected to continue with climate models for the likely emission scenarios where emissions stay at present day levels (RCP 2.6) (Hausfather and Peters 2020) and worst-case scenarios where emissions continue to increase during the 21st century (RCP8.5) indicate that there will be a loss of suitable bioclimatic envelope of between 21% and 99% by the time period 2060 to 2080. Climate models also include new suitable habitat becoming available, an expansion of 50% of suitable habitat under RCP2.6 emission scenario but no new areas are projected under the RCP8.5 scenario. Given the low levels of recruitment from field observations and the fact that heavy browsing pressure from livestock and wildlife is causing significant habitat degradation we suspect that a maximum of 5% of future suitable habitat will be colonized. Future reduction is calculated as =([Negative change cells] - d*[Positive change cells]) / [Present cells], where d* is 5%. Based on this we calculate that under likely emission scenario RCP2.6 the population will decline by a further 19% by 2080.