NATIVE AND NEW PASTURE 23 



scape are, as a rule, slight. The limits of the forest 

 zone have scarcely been altered. The beech forest of 

 the southern Andes seems to be less tenacious than the 

 monte which surrounds the Pampa, and it has been 

 ravaged by fire along the whole edge of the southern 

 steppe at 37° S. lat. The work of man is generally 

 confined to changing the primitive complexion of the 

 natural formations, without altering their general 

 appearance. Thus valuable essences are disappearing 

 from the forest and the scrub, the larch and the cypress 

 from the district of the Patagonian Lakes, and the red 

 quebracho from Santiago del Estero. 



A change that is scarcely visible, but is of consider- 

 able economic importance, thus takes place in the 

 vegetation of the prairie owing to the presence of 

 herds. The pasto Juerte, composed of rough grasses, 

 which is the natural vegetation, is being succeeded 

 by the pasto duke, in which annual species, soft grasses, 

 leguminous plants, etc., predominate. It is mainly 

 composed of plants of European origin. The difference 

 between the pasto dulce and the pasto fuerte or duro 

 is so important for the farmer that there is hardly 

 a single work on Argentina which does not dwell on 

 it. The idea, however, that the pasto dulce has ad- 

 vanced steadily westward, starting from the vicinity 

 of Buenos Aires and constantly enlarging its domain, 

 is not strictly accurate. In 1895 Holmberg ^ traced 

 the western limit of the zone of the pasto dulce through 

 Pergamino, Junin, Bragado, Azul, Ayacucho, and Mar 

 Chiquita. When we compare this with earlier observa- 

 tions, we see that in the course of the nineteenth century 

 the zone of the pasto dulce has extended by about a 

 hundred miles on the southern Pampa. When Darwin 

 travelled from Bahia Blanca to Buenos Aires in 1833, 

 he found no pasto dulce except round Monte, on the 

 right bank of the Salado. Further north, on the other 



' Holmberg, " La Flora de la Republica Argentina," in the Secundo 

 Censo de la Republica Argentina, vol. i. (Buenos Aires, li 



