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Brazil Soils and Vegetation
Soils and Vegetation
Brazil's tropical soils produce 70 million tons of grain crops per
year, but this output is attributed more to their extension than
their fertility. Despite the earliest Portuguese explorers' reports
that the land was exceptionally fertile and that anything planted
grew well, the record in terms of sustained agricultural productivity
has been generally disappointing. High initial fertility after clearing
and burning usually is depleted rapidly, and acidity and aluminum
content are often high. Together with the rapid growth of weeds
and pests in cultivated areas, as a result of high temperatures
and humidity, this loss of fertility explains the westward movement
of the agricultural frontier and slash-and-burn agriculture (see
Glossary); it takes less investment in work or money to clear new
land than to continue cultivating the same land. Burning also is
used traditionally to remove tall, dry, and nutrient-poor grass
from pasture at the end of the dry season. Until mechanization and
the use of chemical and genetic inputs increased during the agricultural
intensification period of the 1970s and 1980s, coffee planting and
farming in general moved constantly onward to new lands in the west
and north. This pattern of horizontal or extensive expansion maintained
low levels of technology and productivity and placed emphasis on
quantity rather than quality of agricultural production.
The largest areas of fertile soils, called terra roxa (red earth),
are found in the states of Paraná and São Paulo. The
least fertile areas are in the Amazon, where the dense rain forest
is. Soils in the Northeast are often fertile, but they lack water,
unless they are irrigated artificially.
In the 1980s, investments made possible the use of irrigation,
especially in the Northeast Region and in Rio Grande do Sul State,
which had shifted from grazing to soy and rice production in the
1970s. Savanna soils also were made usable for soybean farming through
acidity correction, fertilization, plant breeding, and in some cases
spray irrigation. As agriculture underwent modernization in the
1970s and 1980s, soil fertility became less important for agricultural
production than factors related to capital investment, such as infrastructure,
mechanization, use of chemical inputs, breeding, and proximity to
markets. Consequently, the vigor of frontier expansion weakened.
The variety of climates, soils, and drainage conditions in Brazil
is reflected in the range of its vegetation types. The Amazon Basin
and the areas of heavy rainfall along the Atlantic coast have tropical
rain forest composed of broadleaf evergreen trees. The rain forest
may contain as many as 3,000 species of flora and fauna within a
2.6-square-kilometer area. The Atlantic Forest is reputed to have
even greater biological diversity than the Amazon rain forest, which,
despite apparent homogeneity, contains many types of vegetation,
from high canopy forest to bamboo groves.
In the semiarid Northeast, caatinga , a dry, thick, thorny vegetation,
predominates. Most of central Brazil is covered with a woodland
savanna, known as the cerrado (sparse scrub trees and drought-resistant
grasses), which became an area of agricultural development after
the mid-1970s. In the South (Sul), needle-leaved pinewoods (Paraná
pine or araucaria) cover the highlands; grassland similar to the
Argentine pampa covers the sea-level plains. The Mato Grosso swamplands
(Pantanal Mato-grossense) is a Florida-sized plain in the western
portion of the Center-West (Centro-Oeste). It is covered with tall
grasses, bushes, and widely dispersed trees similar to those of
the cerrado and is partly submerged during the rainy season.
Brazil, which is named after reddish dyewood (pau brasil ), has
long been famous for the wealth of its tropical forests. These are
not, however, as important to world markets as those of Asia and
Africa, which started to reach depletion only in the 1980s. By 1996
more than 90 percent of the original Atlantic forest had been cleared,
primarily for agriculture, with little use made of the wood, except
for araucaria pine in Paraná.
The inverse situation existed with regard to clearing for wood
in the Amazon rain forest, of which about 15 percent had been cleared
by 1994, and part of the remainder had been disturbed by selective
logging. Because the Amazon forest is highly heterogeneous, with
hundreds of woody species per hectare, there is considerable distance
between individual trees of economic value, such as mahogany and
cerejeira . Therefore, this type of forest is not normally cleared
for timber extraction but logged through high-grading, or selection
of the most valuable trees. Because of vines, felling, and transportation,
their removal causes destruction of many other trees, and the litter
and new growth create a risk of forest fires, which are otherwise
rare in rain forests. In favorable locations, such as Paragominas,
in the northeastern part of Pará State, a new pattern of
timber extraction has emerged: diversification and the production
of plywood have led to the economic use of more than 100 tree species.
Starting in the late 1980s, rapid deforestation and extensive burning
in Brazil received considerable international and national attention.
Satellite images have helped document and quantify deforestation
as well as fires, but their use also has generated considerable
controversy because of problems of defining original vegetation,
cloud cover, and dealing with secondary growth and because fires,
as mentioned above, may occur in old pasture rather than signifying
new clearing. Public policies intended to promote sustainable management
of timber extraction, as well as sustainable use of nontimber forest
products (such as rubber, Brazil nuts, fruits, seeds, oils, and
vines), were being discussed intensely in the mid-1990s. However,
implementing the principles of sustainable development (see Glossary),
without irreversible damage to the environment, proved to be more
challenging than establishing international agreements about them.
Data as of April 1997
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