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Widdringtonia cedarbergensis, Clanwilliam cedar or Clanwilliam cypress, named Widdringtonia wallichii from 2013 to 2023[1][2][3] is a species of Widdringtonia native to South Africa, where it is endemic to the Cederberg Mountains northeast of Cape Town in Western Cape Province. Due to harsh weather conditions, such as limited rainfall and frequent wildfires, growth is limited.[4] Ring width correlates with rainfall under such harsh environmental conditions.[4] It is threatened by habitat loss[5][6][7] and protected in South Africa under the National Forest Act (Act 84) of 1998.[8]

It is a small evergreen tree growing to 5–7 m (rarely to 20 m) tall. The leaves are scale-like, 1.5 mm long and 1 mm broad on small shoots, up to 15 mm long on strong-growing shoots, and arranged in opposite decussate pairs. The cones are globose to rectangular, 2–3 cm long, with four scales.[5]

Chemical constituents

The wood is used to produce cedarwood oil, which has multiple uses; for example, in Texas cedarwood oil is used as a feedstock, and in Virginia it is used for cosmetics such as perfumes, aftershave lotions, and soaps.[9] Cedarwood oil is also used in home remedies.[9] The essential oil derived from leaves contains terpinen-4-ol (36.0%), sabinene (19.2%), γ-terpinene (10.4%), α-terpinene (5.5%) and myrcene (5.5%).[9] The wood oil contains thujopsene (47.1%), α-cedrol (10.7%), widdrol (8.5%) and cuparene (4.0%).[9]

Conservation of species

W. cedarbergensis is an endangered species facing population decline. Reasons for these declines include habitat loss and inbreeding within populations. Habitat loss results from harsh environmental conditions, and wildfires in the area frequently kill mature W. cedarbergensis trees.[10] W. cedarbergensis has a slower growth rate than its counterparts, which is a factor in the population decline of the species.[10] Genetically, there are several hypotheses about why W. cedarbergensis is not as fire-resistant as some other species within the genus; one of them is heavy logging.[10] The heavy logging to which the current population is subjected causes fragmentation of the population structure and strong selection among the remaining mature trees.[10] Another hypothesis is that the mature trees currently selected for are poorly adapted to fire-intensive environments, resulting in a lack of genetic variation within the gene pool.[10] Further observations suggest that it is not the mature trees themselves that lack fire resistance, but rather their seed recruitment.[11]

Inbreeding occurs within the population of W. cedarbergensis through self-pollination caused by limited pollen movement, which further fragments the population.[10] Seed dispersal is difficult, which limits the success of fertilization in W. cedarbergensis.[12] The seeds are left under the canopy of mature trees, relying on wind and runoff water for dispersal.[12] Other modes of dispersal, such as small animals, are unlikely to assist with the larger seeds.[12] There is no dormancy period after dispersal, which leaves the seeds vulnerable and sometimes unviable.[12]

Methods of conservation

One method of promoting population growth and conservation of W. cedarbergensis is the use of fire. Applying controlled levels of fire during natural seed release, which occurs in late summer and early autumn, helps reduce the litter that affects seed dispersal.[13] Litter during these periods inhibits seed dispersal by blocking the seeds' movement by wind and their access to runoff water, which in turn inhibits regeneration.[13]

Another method is the replanting of seedlings in newly burned areas. Studies suggest that seedlings replanted in newly burned areas, when closely monitored and provided with necessary conditions such as shade, suitable soil, and reduced competition from surrounding seedlings, regrow more successfully than seedlings planted earlier.[14] Using pre-heated seeds in areas previously burned by wildfires also increases the success of growth.[11]

References

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  1. ↑ Linder, H. Peter (2025). Cedars of the Cederberg. SANBI, Pretoria. Template:ISBN
  2. ↑ Template:Cite web
  3. ↑ University of the Witwatersrand: Recommended English names for trees of Southern Africa
  4. ↑ 4.0 4.1 Template:Cite journal
  5. ↑ 5.0 5.1 Farjon, A. (2005). Monograph of Cupressaceae and Sciadopitys. Royal Botanic Gardens, Kew. Template:ISBN
  6. ↑ Template:Cite iucn
  7. ↑ Pauw, C. A. & Linder, H. P. 1997. Widdringtonia systematics, ecology and conservation status. Bot. J. Linn. Soc. 123: 297-319.
  8. ↑ Template:Cite web
  9. ↑ 9.0 9.1 9.2 9.3 Template:Cite journal
  10. ↑ 10.0 10.1 10.2 10.3 10.4 10.5 Template:Cite journal
  11. ↑ 11.0 11.1 Template:Cite journal
  12. ↑ 12.0 12.1 12.2 12.3 Template:Cite journal
  13. ↑ 13.0 13.1 Template:Cite journal
  14. ↑ Template:Cite journal