SAHARAN CYPRESS

Common Name:             Saharan Cypress
Scientific Name:             Cupressus dupreziana

Why is this species important?
There are only 233 known individuals left growing in the wild. They are also one of the 12 plants chosen by the species survival commission of the IUCN to highlight serious threats to species around the globe. The trees are the relict species of a saharan forest, from a time when the area had a milder, more mediterranean climate. They are also amongst the worlds oldest trees, with ages in excess of 3000 yrs. There is a tree in Wadi Tichouinet of average size estimated to be 2200 years old, which has taken three quarters of its life just to grow the last one third of its width.

Where is it found?
This species has a very limited distribution, scattered over a remote 1000 kilometer area of the Tassili N’Ajjer plateau in the south eastern corner of Algeria, at an altitude of 1500-1900m. It is an area described by UNESCO as very exposed, hyper-arid and barren. Estimated rainfall is 30 mm annually but this can be very localised. Average temperatures are in the region of 20-30 degrees but in the winter it can plummet to as low as -7 degrees. Snow has been reported on the higher elevations. The pollen record shows that these trees once had a distribution across the whole of the Sahara. Most of the population now consists of isolated specimens at a density of less than 1 tree per ha. However, there are also a handful of riverbeds that harbour collections of trees, such as at Tamrit, Ngarohad and Jabberen.

How do people use it?
The wood is suitable for the most exacting uses being of medium density, stable and aromatic. Traditionally the timber was used for saddles by the Tuareg and also as a structural timber due to its strength and resistance to decay. There are doors made from this timber in the nearby town of Ghat which have been carbon dated to around 400 years old. It could also be a valuable species for planting in arid regions. The tree has adapted well to this climate and is one of the most drought resistant species known, with considerable frost tolerance too. A recent study has shown that the trees can take quick advantage of even extremely brief wet cycles including winter hoar frost and morning dew, sometimes adding more than one growth ring per year. Conversely, in severe drought the trees may not produce a growth ring at all.

Why is it threatened?
The tree has become a threatened taxon mainly due to its disturbed natural regeneration from grazing by wildlife and stock - camels, donkeys and goats all roam the plateau. Only 3 seedlings have been reported in situ this century (Maire 1952, Camus 1958 and Debazac 1961). As the existing population is made up of predominately mature and over-mature trees in senescence, there is a real risk of eventual extinction in the wild. Though the tree appears to be able to have adapted to the climate and has been able to regenerate in-situ, they cannot survive the constant growing demand for wood fuel that arises from tourist and pastoral activities. Nomads use the trees for shelter and their herds destroy any regeneration. There is still cutting of living branches for firewood but this is isolated thanks in part to trees rarity and remoteness. The area is also part of a well trod emigration route from Niger to Libya and passing groups will also collect firewood from these trees. Losses from firewood collection accounted for 8% of tree deaths between 1972 and 2001. Remarkably, floods are also a threat to the trees, as the wadis that are dry for so much of the year, can quickly become a raging torrent during a flash flood.

What conservation action is needed?
During the past 20 years expeditions at various dates have made collections of cones and seedlings have been raised at many botanic gardens and arboretums. A large collection was made by the Algerian Forest Service in 1969 and several hundred of trees were successfully germinated. The Forest Research Centre at Ariana, Tunis also possess a collection a young trees. The Smith College Botanic Garden (US) includes two trees that were grown from seed collected in 1985 and these are being propagated to enable distribution to other botanical gardens for study and conservation purposes. More recently (2007) a grove of 1300 C.dupreziana trees is being established in an International Arboretum in Canberra, Australia within which will be established forests of rare and endangered species from throughout the world. Formal conservation of the remaining wild population of Saharan Cypress will be required if the species is to be protected. It may be possible to remove adverse pressure in one or two intensively treated and protected sites. The feasibility of an in-situ project will need to be researched.

Selected references

Abdoun F, Jull AJT, Guibal F, Thinon M (2005) Radial Growth of the Sahara’s oldest trees: Cupressus dupreziana. Trees 19: 661-670

Stewart P (1969) Threatened Conifer of the Sahara. Biological Conservation Vol 2: No 1

www.conifers.org/cu/cup/dupreziana.htm

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