Clanwilliam Cedar

Scientific Name
Widdringtonia cedarbergensis J.A.Marsh
Higher Classification
Widdringtonia juniperoides in sense of T.Durand & Schinz, not of Endl. (misapplied name)
Common Names
Clanwilliam Cedar (e), Clanwilliamseder (a), Clanwilliam-seder (a), Sederboom (a), Sederhoutboom (a)
National Status
Status and Criteria
Critically Endangered A2ab
Assessment Date
E.C. February, S. Higgins, S. Fox, D. Raimondo & J.E. Victor
EOO 660 km², AOO 39.6 km². A long-lived tree, endemic to the Cederberg, this species has been declining over the past century due to a deleterious fire regime. Monitoring of permanent plots set up 29 to 35 years ago distributed across this species range indicate a 94% decline of mature individuals has taken place in less than one generation (generation length is estimated to be between 66 and 200 years). Decline has not ceased.
South African endemic
Provincial distribution
Western Cape
Habitat and Ecology
Major system
Major habitats
Cederberg Sandstone Fynbos
Fynbos, rocky areas, predominantly on quartzitic sandstones, prefers areas with 80% rock cover, also occurs on some shales and mudstones. 800-1500 m.
The frequency and intensity of fire have been proposed as the main driver of decline to this species. Manders (1987) suggested that fire frequency was the principal driver, and Fox (2003) notes that there were six fires in 26 years at one site monitored (Grootland) which had caused a ten-fold decrease in the number of adult individuals. Privett (1994) suggested that fire intensity was the main driver of decline noting that mortality resulted from high intensity burns. Higgins et al. (2002) show that both these factors are important but that in addition the average size of fires is also a major cause of decline. February pers. comm. (2008) indicated that during the 1970s fires was excluded from much of the Cederberg this resulted in a large fuel load building up and has caused the average area burnt to become larger overtime. CapeNature fire records between 1958 and 2006 show this trend to be valid. In the past when European farmers arrived they too burnt the area and adopted a patch burn system to provide better grazing. Large numbers of Cedars were reported to have been cut down for telephone poles, for example, 7250 trees cut in 1883 (Andrag 1977). Rodents, hyraxes and baboons are also a potential problem as they are predators of seeds and seedlings, impacting subpopulations ability to recover post fire.

Historical anecdotal reports indicate that the species was formerly abundant within the Cederberg Mountains, and that the first and most severe population decline occurred after European colonizers settled in the area in the late 18th century. The vegetation of the Cederberg is very poor in tree species, and the Clanwilliam Cedar was heavily exploited for timber. In 1879 alone more than 7 000 trees were cut down for use as telephone poles (Andrag 1977). This overexploitation caused a significant population reduction, which is corroborated by the pollen record (Meadows and Sugden 1991). By 1883 no accessible trees of commercial value remained (Mustart 2008). Although it is not possible to quantify exactly the population reduction as a result of timber harvesting, it is suspected that harvesting caused an 80-90% reduction in the population. Although timber harvesting has ceased, the population has never recovered. A synthesis of long-term monitoring data of trees in five permanent plots records a 94% population decline between 1977 and 2003 (Fox 2003). This decline has been attributed to too frequent and intense fires.

Population trend
Protected in the Cederberg Wilderness Area.
This species is not serotinous and releases seeds into a pre-fire environment and therefore most seedlings are inevitably killed by fire. Adults are easily killed by fire and may, at most, only withstand cool, low intensity winter or autumn burns. (Thomas 1995).
Assessment History
Taxon assessed
Status and Criteria
Citation/Red List version
Widdringtonia cedarbergensis J.A.MarshCR A2abRaimondo et al. (2009)
Widdringtonia cedarbergensis J.A.MarshEndangered Hilton-Taylor (1996)
Widdringtonia cedarbergensis J.A.MarshEndangered Hall et al. (1980)

Andrag, R.H. 1977. Studies in die Sederberge oor (i) die status van die Clanwilliam seder (Widdringtonia cedarbergensis Marsh) (ii) buiteligontspanning. Unpublished MSc., University of Stellenbosch, Stellenbosch.

February, E.C. and Stock, W.D. 1998. The relationship between ring width measures and precipitation for Widdringtonia cedarbergensis. South African Journal of Botany 64:213-216.

Fox, S. 2003. An assessment of the population status and demographic models of Widdringtonia cedarbergensis. Unpublished BSc Hons, University of Cape Town, Cape Town.

Goldblatt, P. and Manning, J.C. 2000. Cape Plants: A conspectus of the Cape Flora of South Africa. Strelitzia 9. National Botanical Institute, Cape Town.

Hall, A.V., De Winter, M., De Winter, B. and Van Oosterhout, S.A.M. 1980. Threatened plants of southern Africa. South African National Scienctific Programmes Report 45. CSIR, Pretoria.

Higgins, S., February, E.C. and Skowno, A. 2002. Distribution and population viability of Clanwilliam cedar (Widdringtonia cedarbergensis, Cupressaceae). Final report to WWF-SA Table Mountain Fund.

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

Manders, P.T. 1987. A transition matrix model of the population dynamics of the Clanwilliam cedar (Widdringtonia cedarbergensis) in natural stands subject to fire. Forest Ecology and Management 20:171-186.

Manders, P.T., Botha, S.A., Bond, W.J. and Meadows, M.E. 1990. The enigmatic Clanwilliam cedar. Veld & Flora 76:8-11.

Meadows, M. and Sugden, J. 1991. A vegetation history of the last 14 000 years on the Cederberg, south western Cape Province. South African Journal of Science 87:34-43.

Mustart, P.J. 1993. What is the Cederberg without the cedar? Veld & Flora 79:114-117.

Mustart, P.J. 2008. A synthesis of information on Widdringtonia cedarbergensis (the Clanwilliam Cedar). Unpublished report to the Botanical Society of South Africa.

Privett, S. 1994. Restoration of the Clanwilliam cedar Widdringtonia cedarbergensis: a study on the potential for fire as a management tool. University of Cape Town, Cape Town.

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.

Thomas, J. 1995. The conservation genetics of the Clanwilliam Cedar (Widdringtonia cedarbergensis). Unpublished MSc, University of Cape Town, Cape Town.

February, E.C., Higgins, S., Fox, S., Raimondo, D. & Victor, J.E. 2008. Widdringtonia cedarbergensis J.A.Marsh. National Assessment: Red List of South African Plants version 2020.1. Accessed on 2024/02/29

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Distribution map

© C. Paterson-Jones

© C. Paterson-Jones

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