1 8 BOTANICAL FEATURES OF THE ALGERIAN SAHARA. 



THE FORESTS OF ALGERIA. 



There are estimated to be between 5,000,000 and 8,000,000 acres of 

 forested land in Algeria. Although the forests He mainly in the Tell, cer- 

 tain species, notably Pinus halepensis, occur in the Saharan Atlas as well. 

 Trees also grow along the oueds, especially on the High Plateau, but not 

 in sufhcient abundance to constitute forests proper. The leading species 

 are, among the conifers, Cedrus atlantica and Pinus halepensis. The juni- 

 pers are of importance mainly as a fuel, but do not form forests. Three 

 oaks, namely, Quercus ballota, Q. suber, and Q. lusitanica, are forest-making 

 species, but several other common forms, such as the olive, the plane, the 

 ash, and the betoum (Pistacia), may share in the making of a mixed forest, 

 but do not occur in sufificiently large numbers each to constitute a forest. 

 In 1908 in the civil domain the acreage of the leading kinds of forest trees 

 was as follows: oak, 1,853,520; pine {Pinus halepensis), 1,398,470; juniper 

 (about one-half being Juniperus communis), 444,780; and Cedrus atlantica, 

 85,000. 



The species of trees are distributed in well-defined zones, because of 

 which they may to a large degree be segregated, or at least the specific 

 composition of the forest, if a mixed one, may be determined. In altitudi- 

 nal range, the oaks are found from sea-level to 6,000 feet, within which 

 each species may have its characteristic range. For example, Quercus 

 suber reaches from sea-level to 2,500 feet; Q. ballota from 2,500 to 4,000 

 feet; and Q. lusitanica from 3,500 to 6,000 feet. Pinus halepensis grows 

 from the sea-level to 3,600 feet, and probably much higher in the Saharan 

 Atlas, while Cedrus atlantica is to be found from 4,000 to 6,000 feet. 

 Abies barborensis is said to attain a higher altitude than the cedar. 



Among the definitive physical factors by which the composition of a 

 forest is determined — the rainfall, the temperature, the soil, and the alti- 

 tude — probably of the first rank should be considered the rainfall and the 

 temperature, which are affected by the altitude. In the case of the dis- 

 tribution of the cork oak, however, the character of the soil plays an 

 important role. This species grows only on sandy soil, and where the 

 rainfall exceeds 600 mm. Because of the latter requirement the larger part 

 of the cork-oak forested area is east of Algiers, the annual rainfall to the 

 west of that place falling for the most part under 600 mm. Similarly the 

 minor features of distribution, inside of the specific range, may be ex- 

 plained. For example, in the upper limits of its range, Pinus halepensis 

 appears chiefly on southern slopes, as on Mount Gomo, while at the low 

 altitudes it is to be found on the northern face; temperature reactions 

 apparently — familiar phenomena in mountainous districts. 



Because of the unison of response to common environmental factors, 

 much of the forested area, especially at the higher altitudes, is composed 



