III. PHYSICAL AND VEGETATIONAL ASPECTS OF THE SAHARA
157
The shadows produced by stones and bushes often modify the temperature of the surface of the soil; thus there can be a temperature difference
of greater than 15°C between the shade and the sun. The temperature
of the surface of the sand is not as high in a tuft of vegetation as beyond
it. Also, the relative humidity of the air in the soil is higher in the tuft.
The burrows of rodents and reptiles and the nests of insects—the ants
and the termites—are microclimates analogous to those of the mass of
sand or rocks (Kachkarov and Korovine, 1942; Pierre, 1958; Petter, 1961;
Grenot, 1967, 1968a). The relative humidity in the tunnels and deep
chambers is a function of the proximity to the zones imbibed with water
and isolated from external conditions. Thanks to the microclimatic conditions in the refuges where they stay during the hottest hours of the day,
numerous small animals can escape the noxious effects of the desert
climate.
ACKNOWLEDGMENT
I am greatly indebted to Professor Théodore Monod, Member of the Institute of
France, for having read the manuscript and for providing helpful criticisms. Also, I
wish to thank Mr. Louis Faurel, Joint Director of the Laboratory of Mycology and
Tropical Phytopathology of l'Ecole Pratique des Hautes Etudes de Paris for his
invaluable counseling in the preparation of Section III of this chapter. Animal life
on the Sahara, the author's field, will be discussed in a separate publication.
REFERENCES
Al-Ani, T. A., Habib, I. M., Abdulaziz, A. I. and Ouda, N. A. (1971). Plant indicators. II. Mineral composition of native plants in relation to soils and selective
absorption. Plant Soil 35, 29-36.
Alimen, H. (1957). "The Prehistory of Africa" Hurchinson and Technical, London
(translated by A. H. Brodrik).
Alimen, H. (1963). Considérations sur la chronologie du Quaternaire saharien.
Bull. Soc. Géol. Fr. [7] 5, 627-634.
Alimen, H., Doudoux-Fenet, D., Ferrère, J., and Palau-Caddoux, M. (1957). Sables
quaternaires du Sahara nord-occidental (Saoura-Ougarta). Publ. Serv. Géol.
Alger., Bull. [N.S.] 15, 1-219.
Alimen, H., Chavaillon, J., and Duplaix, S. (1964). Minéraux lourds des sédiments
quaternaires du Sahara nord-occidental. Publ. Cent. Rech. Zones Arides, Cent.
Nat. Rech. Sei., Sér. Géol. 4, 1-73.
Bagnouls, F., and Gaussen, H. (1953). Saison sèche et indice xérothermique. Doc.
Carte Prod. Vég. (Toulouse) 1, Art. 8, 1-47.
Balout, L. (1952). Pluviaux interglaciaires et préhistoire saharienne. Trav. Inst.
Rech. Sahar. 8, 9-21.
Barry, J. P., and Faurel, L. (1963). "Carte de la végétation de l'Algérie, Ghardaïa
au 1/500.000." Institut Cartographie de la Végétation de l'Université d'Alger.
Barry, J. P., Celles, J. C , and Faurel, L. (1970). Carte de la végétation de l'Algérie
au 1/1 000.000°. 1. Alger-Laghouat, 2. El Goléa. 3. In Salah.
157
The shadows produced by stones and bushes often modify the temperature of the surface of the soil; thus there can be a temperature difference
of greater than 15°C between the shade and the sun. The temperature
of the surface of the sand is not as high in a tuft of vegetation as beyond
it. Also, the relative humidity of the air in the soil is higher in the tuft.
The burrows of rodents and reptiles and the nests of insects—the ants
and the termites—are microclimates analogous to those of the mass of
sand or rocks (Kachkarov and Korovine, 1942; Pierre, 1958; Petter, 1961;
Grenot, 1967, 1968a). The relative humidity in the tunnels and deep
chambers is a function of the proximity to the zones imbibed with water
and isolated from external conditions. Thanks to the microclimatic conditions in the refuges where they stay during the hottest hours of the day,
numerous small animals can escape the noxious effects of the desert
climate.
ACKNOWLEDGMENT
I am greatly indebted to Professor Théodore Monod, Member of the Institute of
France, for having read the manuscript and for providing helpful criticisms. Also, I
wish to thank Mr. Louis Faurel, Joint Director of the Laboratory of Mycology and
Tropical Phytopathology of l'Ecole Pratique des Hautes Etudes de Paris for his
invaluable counseling in the preparation of Section III of this chapter. Animal life
on the Sahara, the author's field, will be discussed in a separate publication.
REFERENCES
Al-Ani, T. A., Habib, I. M., Abdulaziz, A. I. and Ouda, N. A. (1971). Plant indicators. II. Mineral composition of native plants in relation to soils and selective
absorption. Plant Soil 35, 29-36.
Alimen, H. (1957). "The Prehistory of Africa" Hurchinson and Technical, London
(translated by A. H. Brodrik).
Alimen, H. (1963). Considérations sur la chronologie du Quaternaire saharien.
Bull. Soc. Géol. Fr. [7] 5, 627-634.
Alimen, H., Doudoux-Fenet, D., Ferrère, J., and Palau-Caddoux, M. (1957). Sables
quaternaires du Sahara nord-occidental (Saoura-Ougarta). Publ. Serv. Géol.
Alger., Bull. [N.S.] 15, 1-219.
Alimen, H., Chavaillon, J., and Duplaix, S. (1964). Minéraux lourds des sédiments
quaternaires du Sahara nord-occidental. Publ. Cent. Rech. Zones Arides, Cent.
Nat. Rech. Sei., Sér. Géol. 4, 1-73.
Bagnouls, F., and Gaussen, H. (1953). Saison sèche et indice xérothermique. Doc.
Carte Prod. Vég. (Toulouse) 1, Art. 8, 1-47.
Balout, L. (1952). Pluviaux interglaciaires et préhistoire saharienne. Trav. Inst.
Rech. Sahar. 8, 9-21.
Barry, J. P., and Faurel, L. (1963). "Carte de la végétation de l'Algérie, Ghardaïa
au 1/500.000." Institut Cartographie de la Végétation de l'Université d'Alger.
Barry, J. P., Celles, J. C , and Faurel, L. (1970). Carte de la végétation de l'Algérie
au 1/1 000.000°. 1. Alger-Laghouat, 2. El Goléa. 3. In Salah.