LAGHOUAT. 29 



a census of the plant population. Here the number of individuals, as well 

 as their size, showed that the moisture relations were good as compared 

 with those of the plain. On an area 16 meters square 422 living perennials 

 were found, mainly of the following species: Acanthyllis tragacanthoides, 

 Asparagus spinosa, Deverra scoparia, and Zollikoferia spinosa. The most 

 numerous, Zollikoferia, was represented by 96 individuals. The general 

 character of the habitat and the plants is sufficiently well shown in fig. 8 

 and does not need further mention in this place. 



EFFECTS OF GRAZING ON VEGETATION NEAR LAGHOUAT. 



It is generally recognized that a potent influence is exerted by man, 

 and the lower animals, in shaping the flora of an arid region, not only as 

 regards the kind and number of plants, but also as concerns certain of the 

 leading characteristics of the plants themselves. The action is largely such 

 as brings about a survival of the "useless" forms, so that we do not know, 

 from the plants we meet in the desert to-day, how many or what kinds of 

 plants it might support. It also may be true that no desert shows the mod- 

 ifying effects of the causes suggested more than the northern Sahara. 



The gazelle (Gazella dorcas) is the leading wild animal preying upon the 

 desert plants in the northern Sahara. It is frequently seen by the traveler 

 to-day and was present in large numbers no longer ago than 50 years (Tris- 

 tram). It is said by the Arabs to feed on the fresh shoots and leaves of 

 many species of shrubs and trees, especially the betoum (Pistacia atlantica) , 

 as well as on the annual vegetation for the relatively short period when it 

 is to be had. Other species of gazelle, according to Tristram, range farther 

 to the south. Other herbivorous animals of the region are hares, antelope, 

 moufflon, and bubale. The moufflon, at the time of Tristram's visit, was 

 "far from uncommon throughout the whole of the mountain districts, 

 whether wooded or bare," but the bubale, "the wildest of the wild game 

 of North Africa," appears not to go north of the Oued Rirh, while its home 

 is farther south. It is impossible to know the number of wild animals 

 subsisting on native desert vegetation, but the list given, which might be 

 extended, suggests that it is by no means small. Although the population 

 of wild herbivorous animals is at present considerable, it was probably 

 much greater a few years ago, the decrease being due, as Tristram says, 

 not so much to the greatly increased population as to the more efficient 

 weapons used by the Arabs in hunting.* 



* Tristram remarks that it " seems that the larger wild animals have been rapidly- 

 decreasing in numbers and are in process of speedy extinction. Dr. Shaw, 150 years 

 since, enumerates in his travels . . . five species of ruminants, which from his descrip- 

 tions must be the bubale, the aoudad or wild sheep, the addax, and the gazelle, as well 

 as the stag. ... As the population has not increased, but rather retrograded, we can 

 only surmise that the substitution of the flint and steel gun for the matchlock of the 

 Bedouin . . . has been fatal in its results to all larger game." It may be remarked that 

 the French impose such restrictions on the Arab as regards the character of the guns he 

 may use (only the army and certain officials of the government employing modern 

 arms) that for the region visited Tristram's description holds fairly well for to-day. 



