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Clanwilliam cedars are extremely long-lived; ring counts have shown some specimens to be over 1,000 years old (5), and it takes around 30 years before an individual will bear a significant crop of seeds
[4)]. In the rocky mountainous area where they are found there is very little rainfall and these cedars must put down extremely long roots to be able to reach the deep groundwater sources (5). These trees have a complex relationship with wild fires which periodically sweep through the region; severe fires are extremely damaging, killing many mature trees, but fires are needed in order to remove vegetation and litter (which otherwise inhibits young seedling growth) and to encourage seed germination (4).
This majestic tree belongs to a genus of trees known as cypress pines (2), tall and straight they dominate the landscape in a similar way to cypresses (3). The evergreen foliage is needle-shaped and compact (3). Both male and female cones appear on the same tree, male cones are small and appear at the end of the twigs in the autumn (4). Female cones are much larger with four thick, warty scales and take almost 3 years to ripen; the seeds are large and wingless (4).
Endemic to South Africa: Western Cape Province, Clanwilliam District, Cedarberg Mountains. Higgins et al. (2002) produced a fine scale model of suitable habitat for this species. The modelled range was then ground-truthed through field surveys, and based on these surveys the extent of occurrence (EOO) of the Clanwilliam Cedar was calculated to be 660 km2. The survey also revealed that only 6% of suitable habitat is occupied by the species with an actual area of occupancy (AOO) estimated to be 39.6 km2. While there are several localities, the number of locations (sensu IUCN) is difficult to determine as the severity and extent of fires (the main threat) can vary depending on their origin or cause.
Found only within the mountain range from which these trees gain their specific name: the Cederberg Mountains of the southwestern Cape in South Africa (6). Historical records suggest that large forests of these trees extended across much of the mountain range but fires and past over-exploitation have reduced the species to just 5 remaining populations (1).
Habitat and Ecology
Habitat and Ecology
Remnant populations of this species are restricted to rocky ridges and cliffs ('krantzes' or 'kranse') of Table Mountain Sandstone, avoiding other formations below and above it. The altitudinal range is (915-)1,000-1,500(-1,650) m a.s.l. The trees are often protected by large boulders from frequent brush fires in the surrounding (secondary) fynbos vegetation. The annual rainfall is between 500-1,000 mm and occurs mostly in the cold winter months, while summers are dry and hot. Systems
The Cederberg Mountains are now dominated by fire-prone 'fynbos', or fine bush vegetation (6), which mainly consists of small leaved, low-growing evergreen shrubs (7). Clanwilliam cedars are particularly associated with rocky ridges or outcrops at around 1,300 metres above sea level (5).
Molecular Biology and Genetics
Barcode data: Widdringtonia cedarbergensis
The following is a representative barcode sequence, the centroid of all available sequences for this species.
Statistics of barcoding coverage: Widdringtonia cedarbergensis
Barcode of Life Data Systems (BOLDS) Stats
Public Records: 2
Specimens with Barcodes: 2
Species With Barcodes: 1
IUCN Red List Assessment
Red List Category Year Assessed
Critically Endangered Red List Criteria
Farjon, A., February, E., Higgins, S., Fox, S. & Raimondo, D. Reviewer/s
Thomas, P. & von Staden, L. Contributor/s Justification
Intensive exploitation in the past, accompanied by changes in intensity and frequency of fires, has resulted in an estimated and observed decline in area of occupancy and quality of habitat of more than 80%. The causes of this decline, while understood, are not reversible and have not ceased. Consequently, Widdringtonia cedarbergensis
is assessed as Critically Endangered under the criteria for A2.
Classified as Endangered (EN - A1cd) on the IUCN Red List 2002 (1).
Historical reports indicate that the species was formerly abundant within the Cedarberg 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 Cedarberg 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: it would be impossible to find even a hundred telephone pole-sized trees in the Cedarberg today (Mustart 2008). Attempts to increase the population through seeding and introduction of ex situ grown plants have been largely unsuccessful.
A synthesis of long-term monitoring data of trees in four permanent plots records a 94% population decline between 1977 and 2003 (Fox 2003). This decline has been attributed to too frequent and intense fires.
Historical exploitation for its valuable timber during the 19th centry led to a reduction of up to 95%. One consequence of this was the expansion of fynbos, a highly flammable vegetation formation. More frequent and more intense fires prevent regeneration; surviving trees are restricted to rocky ridges, ledges, and outcrops mostly beyond reach of the flames. Natural regeneration is also hampered as a result of granivory and herbivory by native rodents.
At the time of European settlement of South Africa the Clanwilliam cedar became massively logged in order to produce furniture, telegraph poles and other structures (8). Vast tracts of the ancient forest have been lost. Today, high-intensity fires represent the biggest threat to survival and groves of dead sliver trees, ravaged by fire, stand out starkly against the landscape (6). In early 2002, large bush fires destroyed around 200 hectares of a cedar plantation (8).
Today the few remaining trees are protected from cutting for any purposes. Cultivation is now undertaken primarily with a view of population restoration and the species is consequently grown in local nurseries as well as in several botanic gardens. Attempts at replanting are continually being made with low rates of success (Mustart et al. 1995) and extensive ex situ conservation efforts are under-way in South Africa, backed by smaller scale plantings elsewhere.
Logging of the Clanwilliam cedar was banned at the turn of the 20th Century but under various pressures such as fire, the population has not shown any signs of recovery (6). A concerted conservation programme to save this ancient giant is now in place, and a 5,252-hectare area has been set aside as a Cedar Reserve (6). Within the reserve, fires are managed and controlled in order to prevent high-intensity summer fires from sweeping through the area. Seedlings are also grown in order to be replanted, and thus help the struggling population to recover. It is hoped that focussing on such a charismatic species will also benefit other members of this unique South African habitat (6).