Maiden's Quiver Tree

Taxonomy
Scientific Name
Aloidendron ramosissimum (Pillans) Klopper & Gideon.F.Sm.
Higher Classification
Monocotyledons
Family
ASPHODELACEAE
Synonyms
Aloe dichotoma Masson var. ramosissima (Pillans) Glen & D.S.Hardy, Aloe ramosissima Pillans
Common Names
Maiden's Quiver Tree (e), Nooiens-kokerboom (a)
National Status
Status and Criteria
Endangered A4ace
Assessment Date
2022/04/13
Assessor(s)
D. Raimondo, P.C.V. Van Wyk, W. Foden, S. Loots, M.T. Hoffman, E. Swart, C.J. Geldenhuys, D. Guo & P. Jacobs
Justification
This species has a restricted distribution to the Gariep Centre of Endemism in northern South Africa and southern Namibia. It has an extent of occurrence (EOO) of 1627 km² and an area of occupancy (AOO) of 136 km². The population has declined by 30-40% over the past 20 years as a result one of the worst recorded droughts in history for the region, much of the mortality observed has been direct drought related, but overgrazing and foraging by wildlife has also caused extensive decline. Climate change models predict that the population will decline by a minimum of a further 19% by the year 2080. This species has a long generation length of 100-150 years. It therefore qualifies for listing as Endangered under criterion A4.
Distribution
Endemism
Not endemic to South Africa
Provincial distribution
Northern Cape
Range
It is restricted to desert mountainsides and arid ravines in South Africa (Richtersveld of the Northern Cape) and southern Namibia. Its distribution is concentrated within the Ai-Ais Richtersveld Transfrontier Park.
Habitat and Ecology
Major system
Terrestrial
Major habitats
Central Richtersveld Mountain Shrubland, Western Gariep Hills Desert, Noms Mountain Desert
Description
It is restricted to karooid and desert mountainsides and ravines where winter precipitation occurs consistently (Loots & Mannheimer 2003). This is a bushy aloe which is doubtfully distinct from Aloidendron dichotomum, except that the main stem rarely exceeds 60 cm. Heat tolerance is remarkable in all tree aloe species including Aloidendron ramosissimum, A. dichotomum, A. pillansii and Aloe pearsonii, which all inhabit the climatically severe Richtersveld in South Africa and Namibia, where summer temperatures can exceed 50°C (Cousins and Witkowski 2011). Tree growing forms in this family, including Aloidendron ramosissimum, usually present poor fire tolerance due to lack of insulating skirts of dead leaves (Bond 1983). Moreover, species such as A. dichotomum, A. pillansii, A. ramosissimum and Kumara plicatilis, generally do not resprout after mechanical damage (E. Van Jaarsveld pers. comm. in Cousins and Wirkowski 2012). The generation length of this species is conservatively estimated to be between 100 and 150 years, this was inferred from the limited growth or change in individual plants within permanent plots observed over a 40 year period from 1980 to 2020 by the BIOTA Biodiversity Observatories in Africa project (Jürgens et al. 2012). There has been limited recruitment observed in the past 20 years and seed set is generally low with fruits typically parasitized by insect larvae.
Threats
Due to the species' slow growth and poor ability to respond to disturbances such as overgrazing or mechanical damage, any disturbance is likely to have a long term effect on the population (Hoffman et al. 2010). Since 2004 there has been ongoing habitat degradation as a result of trampling and overgrazing by livestock in the Richtersveld. The entire range of this species has been negatively impacted by one of the worst recorded droughts in history for the region. This has reduced the availability of winter precipitation events which the species relies on for recruitment. Furthermore, grazing and browsing availability in the region has been significantly reduced (Michler et al. 2019). This has increased foraging pressure by domestic and indigenous fauna likely leading to the increased mortality of the juvenile age class. Other species of Aloidendron near Rosh Pinah, southern Namibia (Loots and Mannheimer 2003) are negatively impacted by mining and considering the spatial overlap of A. ramosissimum in these areas, this threat is likely impacting this species too. However, the extent and rate to which this is a threat has not been explicitly measured or observed. Climate models also indicate that there will be ongoing loss of suitable bioclimatic habitat for this species. Due to the unique growth form of the Aloidendron genus, theft of individuals by horticultural collectors has been recorded, however this species is not as popular in trade as Aloidendron dichotomum and Aloidendron pilansii.
Population

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 (van Wyk, P. pers. comms. 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, north-west 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) (Jacobs, P. pers. comms. 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 (RCP 8.5) 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 RCP 2.6 emission scenario but no new areas are projected under the RCP 8.5 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 RCP 2.6 the population will decline by a further 19% by 2080.


Population trend
Decreasing
Conservation
The species is listed in CITES Appendix II. Much of its range occurs in the Ais/Richtersveld Transfrontier National Park.
Notes
Sporadic illegal collection events have taken place in the past, but this species is not very popular in trade and collection levels are low.
Assessment History
Taxon assessed
Status and Criteria
Citation/Red List version
Aloidendron ramosissimum (Pillans) Klopper & Gideon.F.Sm.VU B1ab(iii,v)2015.1
Aloidendron ramosissimum (Pillans) Klopper & Gideon.F.Sm.EN B1ab(iii,v)2014.1
Aloe ramosissima PillansEN B1ab(iii,v)Raimondo et al. (2009)
Aloe ramosissima PillansVU A1ceVictor (2002)
Aloe ramosissima PillansVulnerable Hilton-Taylor (1996)
Bibliography

Bond, W. 1983. Dead leaves and fire survival in southern African tree aloes. Oecologia 58:110-114.


Foden, W. 2002. A demographic study of Aloe dichotoma in the succulent Karoo: are the effects of climate change already apparent? , University of Cape Town.


Foden, W., Midgley, G.F., Hughes, G., Bond, W.J., Thuiller, W., Hoffman, M.T., Kaleme, P., Underhill, L.G., Rebelo, A.G. and Hannah, L. 2007. A changing climate is eroding the geographical range of the Namib Desert tree Aloe through population declines and dispersal lags. Diversity and Distributions 13:645-653.


Grace, O.M., Klopper, R.R., Figueiredo, E. and Smith, G.F. 2011. The Aloe names book. Strelitzia 28. South African National Biodiversity Institute, Pretoria.


Grace, O.M., Klopper, R.R., Smith, G.F., Crouch, N.R., Figueiredo, E., Rønsted, N. and Van Wyk, A.E. 2013. A revised generic classification for Aloe (Xanthorrhoeaceae subfam. Asphodeloideae). Phytotaxa 76(1):7-14.


Hilton-Taylor, C. 1996. Red Data List of southern African plants. 1. Corrections and additions. Bothalia 26(2):177-182.


Hilton-Taylor, C. 1996. Red data list of southern African plants. Strelitzia 4. South African National Botanical Institute, Pretoria.


Hilton-Taylor, C. 1998. Assessment of Southern African Trees for WCMC.


Hoffman, M.T., Rohde, R.F., Duncan, J. and Kaleme, P. 2020. Repeat photography, climate change, and the long?term population dynamics of tree aloes in southern Africa. Repeat photography: methods and applications in the natural sciences. Island Press, Washington DC.


Jordaan, M. and Van Wyk, A.E. 2015. Gymnosporia swazica (Celastraceae), a new species from southern Africa. Phytotaxa 192(4):296-300.


Jürgens, N., Schmiedel, U., Haarmeyer, D.H., Dengler, J., Finckh, M., Goetze, D., Gröngröft, A., Hahn, K., Koulibaly, A., Luther-Mosebach, J. and Muche, G. 2012. The BIOTA Biodiversity Observatories in Africa—a standardized framework for large-scale environmental monitoring. Environmental monitoring and assessment 184(2):655-678.


Klopper, R.R. and Smith, G.F. 2007. The genus Aloe (Asphodelaceae: Alooideae) in Namaqualand, South Africa. Haseltonia 13:38-51.


Loots, S. and Mannheimer, C. 2003. The status of Aloe pillansii L.Guthrie (Aloaceae) in Namibia. Bradleya 21:57-62.


Michler, L.M., Treydte, A.C., Hayat, H. and Lemke, S. 2019. Marginalised herders: Social dynamics and natural resource use in the fragile environment of the Richtersveld National Park, South Africa. Environmental Development 29:29-43.


Raimondo, D., von Staden, L., Foden, W., Victor, J.E., Helme, N.A., Turner, R.C., Kamundi, D.A. and Manyama, P.A. 2009. Red List of South African Plants. Strelitzia 25. South African National Biodiversity Institute, Pretoria.


Setshogo, M.P. 2005. Preliminary Checklist of the Plants of Botswana 37. Southern African Botanical Diversity Network Report, SABONET, Pretoria and Gaborone.


Van Wilgen, N.J., Goodall, V., Holness, S., Chown, S.L. and M.A., M. 2016. Rising temperatures and changing rainfall patterns in South Africa's national parks. International Journal of Climatology 36(2):706-721.


Van Wyk, B.-E. and Smith, G. 2003. Guide to aloes of South Africa. (2nd ed.). Briza Publications, Pretoria.


Victor, J.E. 2002. South Africa. In: J.S. Golding (ed), Southern African plant Red Data Lists. Southern African Botanical Diversity Network Report 14 (pp. 93-120), SABONET, Pretoria.


Walker, C.C. and Vanden Bon, A. 2018. Aloe pearsonii - a unique species in habitat and in cultivation. CactusWorld 36(1):33-40.


Williamson, G. 1998. The ecological status of Aloe pillansii (Aloaceae) in the Richtersveld with particular reference to Cornellskop. Bradleya 16:1-8.


Citation
Raimondo, D., Van Wyk, P.C.V., Foden, W., Loots, S., Hoffman, M.T., Swart, E., Geldenhuys, C.J., Guo, D. & Jacobs, P. 2022. Aloidendron ramosissimum (Pillans) Klopper & Gideon.F.Sm. National Assessment: Red List of South African Plants version . Accessed on 2024/11/09

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Distribution map

© C. Paterson-Jones

© C. Paterson-Jones

© L. von Staden

© L. von Staden

© E.J. van Jaarsveld


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