Agriculture Reference
In-Depth Information
6
Fire in Chile
The Mediterranean-type Climate Region of Chile
The mediterranean-type climate (MTC) in Chile (
Fig. 6.1
) is distributed from La
Regio´ n X) in the south. It is constrained to the west side of the Andean mountain
range, although as the height of this range decreases in the south, aMTC is observed
at least as far eastward as Bariloche, Argentina. Although a pattern of winter rains
and summer droughts extends northward into the Atacama Desert, this area falls
outside our definition of MTC because winter evaporation exceeds rainfall in these
areas of extremely low precipitation. The northern border of the MTC region is the
transition from desert communities to shrubby matorral, while the southern border
corresponds to the point of transition from sclerophyll woodlands to Valdivian
evergreen forests (Gajardo
1994
; Amigo & Ramirez
1998
; Rundel
et al.
2007
).
The landforms of central Chile can be divided into three north-south trending
geomorphic zones (
Fig. 6.1
): the Coastal Cordillera, the Central Valley, and the
high Andean Cordillera (Armesto
et al.
2007
). The Coastal Cordillera rises
relatively sharply from the coast, with little extent of coastal terraces, and reaches
elevations as high as 2222 m at Cerro Roble and 1880 m at Cerro Campana,
which lie between Valparaı´ so (Regio´ n V) on the coast and Santiago (Regio´ n
Metropolitana) at the base of the Andes. The Central Valley is a structural basin
filled to great depth by sediments from the surrounding mountains. North of
Santiago, spurs from the Andes extend west across the valley and connect with
the Coastal Cordillera, separating individual river basins such as that of the
Rı´ o Aconcagua (Regio´ n V). From Santiago to the south, however, the valley
extends uninterrupted for a distance of 900 km to Puerto Montt (Regio´ n X), with
typical elevations of 400-700 m. The Andean Cordillera marks the eastern bound-
ary of the MTC zone of central Chile. It is the product of complex tectonic activity
beginning in the Cretaceous (see
Fig. 9.1
), but with major uplift in the late Tertiary.
Paleobotanical evidence suggests that the central Andes had not attained more
than half their current elevation by 10 Ma (Gregory-Wodzicki
2000
), but was close
to the present height by the end of the Miocene (Reynolds
et al.
1990
). Elevations
reach from 4000 m to nearly 7000 m. To the north of Santiago the Andes are largely
composed of metamorphosed sedimentary rock, but a major volcanic zone extends
from south of Santiago through the Lake District (Los Lagos Regio´ n X).
