A large portion of northern and central Chile enjoys a mediterranean-type
climate of warm, dry summers and cool, wet winters. This region has been
divided into five subdivisions, ranging from hyperarid in the north to
perhumid in the south [Di Castri and Hajek 1976]. A great proportion of the
central Valley ('Intermediate Depression'), lying between Copiapo to the
north and Concepci6n in the south, the Cordillera de los Andes in the east,
and the lowlying coastal Cordillera in the west, is covered with a plant
formation known as 'espinal' (plural: espinales) (Fig. 1).* The dominant
species of these espinales is a small, spiny leguminous tree, Acacia caven,
locally known as 'espino'. It is noteworthy that a single tree species should