Cupressaceae

Widdringtonia schwarzii (Marloth) Mast.

Endemic to the eastern Cape Province of South Africa where past over-exploitation has greatly reduced the population; today the major threats include wildfires

Distribution

Endemic to the Eastern Cape Province of South Africa. It is recorded from the Kougaberg and Baviaanskloof mountains in the Willowmore District, where it grows in rocky ravines and canyons ['kloofs'] draining into the Baviaanskloof River and its tributaries. The extent of occurrence is estimated to be less than 1,200 km², with a very small area of occupancy ranging from 7 km² to 28 km² depending on the method used to estimate it. The number of locations is between 5 and 12.

The global population is restricted to scattered trees and/or small stands in isolated localities which form 5-7 subpopulations. The number of mature trees is not known. Some stands have been burnt in recent years but it is uncertain if this represents an overall decline due to lack of information about the total population size and recruitment success after fires.

Habitat and Ecology

Widdringtonia schwarzii occurs in rocky ravines on steep slopes or cliffs ('krantzes') and in (dry) river beds of canyons between (600-)900-1,200 m a.s.l. Trees can attain large size in rocky streambeds of canyons, sheltered from fires, where they can form small groves. The surrounding vegetation is various types of fynbos (mostly restioid fynbos). The most reliable rainy seasons are spring and autumn as the area lies to the east of the main winter rainfall zone and west of the summer rainfall zone; the dry, hot summers are somewhat tempered by the sheltered micro-climate in deep, shady canyons, where deeper ground water remains available under stream beds.

Human Uses

Willowmore Cedar was used in the past for construction timber of local farmsteads, for furniture making, fences and telegraph poles. Depletion of the resource to a few trees in inaccessible locations terminated this use and the remaining trees are now protected.

Conservation Status

Global status

Near Threatened (VU D2 / CR A2cd, B2ab(ii,iii,iv,v))

Widdringtonia schwarzii has a restricted distribution in the Baviaanskloof Wilderness Area. There is some uncertainty about its area of occupancy although it is considerably less than 500 km². The number of locations is between 5 and 12 depending on the method used to determine them. The species was heavily exploited in the past for its durable timber that was used for house construction, but most logging probably took place more than 120 years ago (i.e. more than three generations ago). Its habitat has also been modified by the increased frequency of fires as a result of human activities in the area and the expansion of agricultural activities. wildfires are the main threat, as this species is ill adapted to (frequent) fires. In 2008 wildfires affected stands in the Cedar Valley area; floods in 2010 also had an impact. The extent of past decline is difficult to quantify due to a lack of information about the extent of its past distribution. The most recent Red List of South African Plants (Raimondo et al. 2009) assessed this species as Near Threatened on the basis that it almost met the D2 criterion for Vulnerable. Given the discovery of additional localities in the Kouga Mountains, it seems unlikely that any single threatening event would impact the whole area to drive this species very quickly to Critically Endangered or extinction. In this assessment the Near Threatened category is maintained but on the basis that it almost meets the criteria for listing as threatened under criteria B2ab(ii,iii,v) and possibly A2cd.

Conservation Actions

In recent years, new localities have been found in remote upper parts of canyons in the Kouga Mountains, some of which harbour large trees. There is now much awareness of its conservation value and an active management programme (largely to prevent wildfires) is being implemented. Further cutting of trees is prohibited. Almost all subpopulations occur within the Baviaanskloof Wilderness Area. A limited amount of ex situ conservation has been undertaken in the form of seed collections and plants are grown in botanical gardens (e.g. Kirstenbosch National Botanical Garden in Cape Town). There is an active programme to control and eradicate any alien invasive plant species, but regular monitoring is required that no new infestations affect the area.

References and further reading

  1. Boshoff, A., Cowling, R. and Kerley, G. 2000. The Baviaanskloof Conservation Area: a tourism and development priority. Report No. 27. Available at: http://ace.nmmu.ac.za/ace/media/Store/documents/Technical%20reports/TERU-Report-27-Boshoff-et-al-2000-Baviaanskloof-Conservation-Area.pdf
  2. Farjon, A. 2010. A Handbook of the World's Conifers. Koninklijke Brill, Leiden.
  3. Farjon, A. (2013). Widdringtonia schwarzii. In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.1. <www.iucnredlist.org>. Downloaded on 07 July 2013.
  4. Friends of the Baviaanskloof Wilderness Area Trust. 2012. Saving the Baviaanskloof cedar (Widdringtonia schwarzii) campaign: Standard operating procedure
  5. 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
  6. Victor, J.E. and van Wyk, A.E. 2005. Widdringtonia schwarzii  (Marloth) Mast. National Assessment: Red List of South African Plants version 2013.1.
  7. Ward, J.H. 1958. Notes on the cedar of Willowmore, Widdringtonia schwarzii. Journal of the South African Forestry Association 31(1): 81-84.

External links