Impacts of Land-use Change on Carbon Stocks and Dynamics in Central-southern South American Biomes: Cerrado, Atlantic Forest and Southern Grasslands - Soil Carbon: Science, Management and Policy for Multiple Benefits - page 245

forestry area grew by 23.0% (ABRAF, 2012).
The Brazilian states with the highest Euca-
lyptus spp. plantation expansion rates dur-
ing this period were Mato Grosso do Sul
(30%), Maranhão (10.2%), Tocantins (7.3%)
and Minas Gerais (7.7%), all under charac-
teristic Cerrado vegetation and climate.

Cerrado

The Cerrado biome covers approximately 2 mil-
lion km 2 , which represents approximately
25% of Brazil (Sano et al ., 2008). In size, the
Cerrado biome is the second largest ecosys-
tem in Brazil after the Amazon. With 6500
plant species, the Cerrado has only 23%
fewer species than the Amazon; it is one of
the most diverse tropical biomes and the
most species-rich tropical savannah in the
world (UNEP, 2010). A vast portion of this
biome contains the headwaters of the Parana
and Paraguay River sub-basins, components
of the La Plata River Basin. The original Cer-
rado landscape suffered widespread trans-
formation after agricultural innovations pro-
vided technologies and crop varieties adapted
to the Cerrado soils and climate (Miyasaka
and Medina, 1981; Spehar, 1995). Several au-
thors have suggested that the Cerrado is being
modified due to land-use expansion, particu-
larly for grain crops and pastures (Fearnside,
2001; Klink and Moreira, 2002). This effect
is due partly to the fact that the more open,
savannah-type structure invites human settle-
ments and developments. The southern por-
tion of the Cerrado biome, located in the La
Plata River Basin, is where most of the land-
use conversion to agriculture and pasture has
taken place (Plate 13). The Brazilian states of
São Paulo, Goiás and Mato Grosso do Sul
were reported to have retained only 15- 32%
of their native Cerrado vegetation (2002 land-
use data) (Sano et al ., 2008).
LUC in the Cerrado initially aimed at
opening the frontier for cattle grazing. Typic-
ally, the occupation began with the removal
of native woody Cerrado vegetation for
charcoal production, mostly used as an en-
ergy source for steel mills located elsewhere
in Brazil (Uhlig et al ., 2008).
The second major LUC process was the
expansion of cash crops, especially soybeans
(Spehar, 1995; Alves et al ., 2003) ( Fig. 21.1) .
Currently, more than 60% of Brazil's soy-
bean production derives from the Cerrado
(Souza et al ., 2007), where it occupies an
estimated area of approximately 13 Mha.
Land is steadily converted to forest plant-
ations in the Brazilian Cerrado at an average
annual rate of 3.5%. From 2005 to 2010, the

Southern Grasslands

Agricultural expansion into the marginal
semi-arid regions of the La Plata River Basin,
such as the provinces of La Pampa and San
Luis, increased deforestation of the native sa-
vannah vegetation significantly in favour of
sunflower, soybean and maize crops. Despite
the relatively adverse climatic conditions for
soybean cropping, the area planted to this crop
in La Pampa expanded by 370% during the
past decade, and grain production followed a
similar trend with a 360% increase (Fig. 21.2) .
Traditionally, the cash crops in this
semi-arid, marginal agricultural region have
been wheat since the early 20th century and
sunflower since the 1970s. The soybean ex-
pansion has reduced the planted areas of
both these crops, especially that of wheat
( Fig. 21.3 ). The total cropped area, however,
has decreased by about 30% during the last
decade, from 942,000 ha in 2000 to 659,000 ha
in 2008, due to drought events in 2004 and
2007-2009 (Gobierno de La Pampa, 2009).
Apart from expanding, agriculture has
also intensified and industrialized through-
out the region. While traditional agriculture
was based on diversified mixed systems that
implied rotations of cash crops with perman-
ent pastures for livestock production, at pre-
sent, especially in the Argentinean Grasslands,
monocultures of cash crops predominate.
At the same time, afforestation of mar-
ginal lands has become an important feature
of LUC in the Southern Grasslands biome
due to increasing demands from the paper
industry. Results from ongoing studies
show that forest cover on soils originally
formed under grassland in the Argentinean
Pampas has significant effects on their
chemical and physical properties, resulting
in significant impacts on soil fertility, car-
bon stocks and hydrology.