Agriculture Reference
In-Depth Information
Excluding the heavily modified areas of the Central Valley that are largely
agricultural today, various shrublands comprise over two thirds of the land cover
of the MTC region of Chile (see Table 1.1). Evergreen sclerophyllous forests and
woodlands make up 20% of the area. Further south, winter-deciduous forests
with
Nothofagus
dominate the southern portions of the country.
The austral Valdivian rainforests of the Lake District of south-central Chile
(39
30
0
-43
30
0
S; Regiones VIII and IX) lie beyond the traditional definition used
in Chile of the mediterranean zone, but retain a strong MTC of winter precipita-
tion with dry summers comparable to that of western Oregon in North America.
Native forests today cover about half of this region, with much of this concen-
trated on the western slopes of the Andes. The lower coastal ranges in this area
have been heavily deforested, as has the Central Valley. The most widespread
forest community is the Valdivian rainforest with a moderately diverse assemblage
of evergreen broadleaf trees including
Nothofagus dombeyi
,
Laureliopsis philippi-
ana
,
Eucryphia cordifolia
,
Aextoxicon punctatum
and other species (Donoso
1993
,
Ramı´ rez & San Martin
2005
). Here, landslides and volcanic eruptions are the most
important natural disturbances (Veblen
et al.
1979
,
1980
), with fire much less
important. Higher-elevation montane forests are dominated by deciduous species
of
Nothofagus
. Forest stands with a major canopy cover of conifers are rare in
these austral forests. The exceptions are seral stands of
Araucaria araucana
(see
Fig. 9.2
) in the northern margin of the Lake District, small areas of
Austrocedrus
chilensis
in the Andes, and scattered forests of
Fitzroya cupressoides
in both the
Coastal Cordillera and Andes. Large areas of the coastal ranges now support
plantation stands of
Pinus radiata
(Estades & Escobar
2005
).
Much of the coastal region at this latitude is very wet but eastward there are
many pockets of drier landscapes with a clear MTC, for example as around
Bariloche, Argentina (41
06
0
S/71
10
0
W). Associated with this MTC are
matorral shrublands that are subject to fire. Although the strong summer dry
conditions of MTCs do not extend into the Patagonia region of southern
Chile, patches of fire-prone matorral occur in the region. These are often
dominated by a resprouting shrub form of
Nothofagus antarctica
, forming
shrublands as well as the understory of
Araucaria
forests (Steinke
et al.
2008
). Large areas of these shrublands have burned at irregular intervals
(Cerrillo
et al.
2008
).
Fire Regimes
Throughout the MTC region of Chile summer wildfires are widespread (Monte-
negro
et al.
2004
). The fire season extends from October through April, with more
than three fourths of all fires occurring during the summer months of December
(13% of fires), January (26% of fires), and February (39% of fires). On average,
some 5400 fires are recorded each year, affecting an average of 52 400 ha. These
averages, however, do not indicate the ongoing trends in increased fire frequency
