Agriculture Reference
In-Depth Information
Arguably the most extensive anthropogenic transformations have occurred in the
Mediterranean Basin and in the last millenium humans have been responsible for
major transformations of woodlands (Marsh
1864
). Fire was the primary tool
used to transform wooded landscapes to herbaceous associations (Trabaud
et al.
1993
;Henderson
et al.
2005
). Additionally, these land-use practices were widely
transferred to all other MTC regions from the sixteenth to the eighteenth centuries
(Pyne
1982
,
1991
,
1995
), although sometimes new settlers assimilated native burning
practices (Deacon
1992
). Timing of European colonization played a role in landscape
impacts. In, Chile, Europeans arrived relatively early and these landscapes have had
intensive rural land use since the sixteenth century. Today there are very few parts
of central Chile that have not been affected by goat grazing and wood collecting
for charcoal production (Bahre
1979
). These activities greatly reduced fuel continuity
and undoubtedly affected burning patterns. Europeans arrived much later in
California, only about 100 yrs prior to the Industrial Revolution of the 1880s that
resulted in massive rural to suburban migration, and which minimized the duration
of intensive land use. European colonization of both South Africa and Western
Australia had variable impacts dependent on geology as ecosystems such as fynbos
and kwongan on nutrient-poor soils were of limited value, but vegetation types on
other soils were converted to agricultural and pastoral uses.
European colonists regularly utilized fire in MTC regions primarily for increasing
pasturage (Pyne
1982
; Rundel
1998
). Colonists, in addition to adding new ignitions
to the landscape, also reduced other sources of ignitions, either through the decima-
tion of native populations or through regulations imposed against continuation of
native burning practices. Sometimes these laws were rather harsh, as in the Dutch
death penalty against second offenders in South Africa (Bands
1977
). In addition,
other land management practices altered fuels through grazing and timber harvest-
ing, which in turn affected fire activity (Griffiths
2002
). The net effect on the fire
regime is often debatable and seldom does one find a consensus on such issues. For
example, in Australia it is widely thought that burning increased with the arrival of
Europeans (Singh
et al.
1981
;Banks
1989
;Kershaw
et al.
2002
; Mooney
et al.
2001
).
An alternative model is that Aboriginal burning was frequent and in harmony
with the environment, and that this was immediately suppressed by European
colonizers (Kimber
1983
;Burrows
et al.
1995
). Fire-scar dendrochronology records
from southwestern Australian forests reveal a marked increase in fire scars
following European colonization (Burrows
et al.
1995
), which would normally be
interpreted to mean an increase in fire use. However, proponents of Aboriginal fire
use have argued that increased fire scarring following colonization was in fact due to
a decrease in fire frequency because Aboriginal burning was so frequent it kept fuel
levels below the threshold required to scar trees. In their view Europeans reduced
the frequency of burning and this resulted in fewer, but higher intensity fires.
Independent tests of this interpretation of fire-scar data failed to support it
(Richards
2000
) and other studies have found fire scars are a consistent indicator
of fire frequency in Western Australian
Callitris
trees (O'Donnell
et al.
2010
),
supporting an increase in fire activity with European colonization.
