Cupressus dupreziana description

Cupressus dupreziana Camus 1926

Common Names

Tarout (Tuareg) (4).

Taxonomic notes

Syn: C. lereddii Gaussen 1950 (4). "There is a possibility that at an earlier period C. sempervirens may have been much more widely distributed than at present and that C. dupreziana may be a geographical form of that species. The differences between the two species might well be due to environment" (3).

The species was described "based on fragmentary material collected by M. Lavauden during his journey over the Tassile range in the Sahara between Rhat and Djanet early in 1925" (3).

Description

Tree to 20m tall (the tallest measured, 20 m, has lost its top) and 3 m dbh. All known mature trees are too badly mutilated for their natural form to be seen [but see the photo]. Young specimens grown in protected conditions are first bushy, later developing a straight central axis. Bark is reddish-brown, with deep longitudinal fissures, lacking decortication. Branches diverge from the trunk at large angles, curving upwards. Ramification of first and second order shoots tends to be strong in 2 planes; first-order shoots are flattened. Leaves are cupressoid scales, opposite, decussate, imbricate, slightly appressed, acuminate, 1-1.5 mm long, dull green, slightly glaucous; resin gland elongated, not noticeable except on the base of old leaves. Foliage very dense. Seedlings have with 2 cotyledons and glaucous, aciculate leaves 2-3 mm long. Plants monoecious. Pollen cones terminal, yellow, elongate, 6×3 mm. Female cones terminal, purple, ovoid, c. 2.5 mm diameter, developing into and elongated cone 18-24 × 16-20 mm; grey-brown, matte, with 12-19 scales having a very small, rounded mucro. Seeds reddish-brown, oval, flattened, 4-5×5-6 mm, with wide, thin wings. Pollen spherical, 38 microns diameter (4).

Range

Algeria: Confined to an area of some 200 km² on the Edeni (or Tamrit) plateau of the Tassili N'Ajjer massif in the central Sahara, around 9°E 25°N, at 1000-1800 m elevation. The summer temperatures are estimated to be ca. 20-30°C, in winter ca. 1-13°C. Frosts of –7°C likely occur. Annual rainfall is ca. 30 mm, highly variable. The trees grow in wadis on alluvial gravels and sands (4).

There are 153 living specimens and many more snags. Only two cases of naturally occuring seedlings have ever been recorded, and there are no trees younger that at least a century (only 5 trees have been recorded with a dbh 50 cm or less, the smallest being 13 cm) (4). It is believed that the water table has sunk to an extent that impedes regeneration. The species is assessed as rare and critically endangered (5).

Big Tree

Said to be a specimen in Tamanarasset, Algeria (2). "According to native accounts trees up to 40 ft. in girth were found formerly" (3).

Oldest

Dendrochronology

Ethnobotany

It rarity is due to exploitation by native peoples. Nomads often shelter under the trees and their herds destroy any regeneration. There is still sporadic exploitation of living branches for firewood, but systematic cutting of the cypresses has been brought to an end by their rarity and remoteness. There were still many living trees in 1863 according to the first European report and they were still a major source of timber for local use (4).

This is one of the most drought-resistant species known, with considerable frost tolerance. The wood is suitable for most exacting uses, being of medium density, stable and aromatic. The stems are straight in cultivation and the branches fine. Growth is reportedly a little slower than that of Cupressus sempervirens in similar conditions. it could be a valuable species for planting in arid regions (4).

Observations

May only be seen in the wild in the Tassili N'Ajjer National Park, which has been designated a World Heritage Site. The species has been successfully established in cultivation (5).

Remarks

"According to Duveyrier, extensive forests of this cypress formerly occurred in the region named, but have since been almost completely destroyed for the sake of their timber which has largely been employed for house-building at Djanet and Rhat" (3).

Since 1987 a project has been underway to sustain and re-introduce the cypress to the Tassili plateau (6).

Citations

(1) Silba 1986.
(2) Vladimir Dinets, e-mail communications, 12 Jan 1998.
(3) Dallimore & Jackson 1967.
(4) FAO Forestry Department. 1986. Databook on endangered tree and shrub species and their provenances. Rome: FAO. 524 pp.
(5) World Conservation Monitoring Centre - Trees database, URL=http://www.wcmc.org.uk/cgi-bin/SaCGI.cgi/trees.exe, accessed 1-Jul-1999.
(6)Tassili N'Ajjer National Park is described at http://www.wcmc.org.uk/protected_areas/data/wh/tassili.html (accessed 9-Jul-1999).

It sounds like an extremely interesting area for natural and human history in general.