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Large-scale clearing for agriculture in the Brazilian Amazon.
(Photo courtesy of Jacques Descloitres, MODIS Rapid Response Team, NASA/GSFC)
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COMMERCIAL AGRICULTURE
Agricultural use of some rainforest land proves to be a failure because of the nutrient-deficient, acidic soils of these forests. Nevertheless, many commercial agricultural projects are still carried out on rainforest lands,
although many of these revert to cattle pasture after soils are depleted. Some floodplain regions, like
those of the lower Amazon (várzea), are more suitable for commercial agriculture because annual floods replenish
nutrient stores.
Generally forest clearers use slash-and-burn techniques to clear land, but on a much larger scale
than traditional practices. Instead of burning a mere 2-10 acres (1-4 ha), agriculturalists burn hundreds to thousands
of hectares. This slash-and-burn technique is generally wasteful since it is only occasionally that trees with timber value are removed before the forest is clear cut and left to dry. Following cutting, the area is burned to release nutrients locked up in vegetation and produce a layer of nutrient-rich material above the poor soils of the former tropical forest. The cleared area is quickly planted and supports vigorous growth for a few years, after which the
nutrient stock is depleted and copious amounts of fertilizer are required to keep the operation viable. Fertilizer may be washed into local streams, affecting fish and aquatic life. When the use of fertilizer is deemed no longer efficient, the land is abandoned and allowed to
revert to scrub. Drought-resistant grasses may move in or cattle ranchers may plant imported African grasses for
cattle grazing. The land is now only marginally productive and a limited number of cattle can subsist in the area.
When the land is suitable for agriculture, generally large single cash crops like rice, citrus fruits, oil palms, coffee,
coca, opium, tea, soybeans, cacao, rubber, and bananas are cultivated. Some of these crops are better adapted to
such conditions and last longer on cleared forest lands. However, there are several problems with this type of monoculture
(single crop plantations) in the tropics, besides the loss of forest. First, such planting of a single crop makes
the crop highly vulnerable to disease and pests, as periodic infestations have shown in Brazil, India, and other
places. In natural rainforest, widespread infestations are rare because individuals of a given species are widely
dispersed. Second, the planting of monocultures can be economically risky with the price fluctuations so common in international commodities markets.
Additionally, a single cold spell or drought
can devastate a tremendous part of the agricultural economy.
In the state of Acre in western Brazil, farms and pastures are surrounded by large, undisturbed areas of Amazon rainforest. Since January 2005, many areas in the state have been experiencing severe drought, and the forests have become tinder dry. Since August, agricultural fires—many of them ignited in violation of a state-declared ban—have been escaping control, racing through adjacent fields and spreading into the forests. The situation deteriorated through September, and record amounts of previously undamaged rainforest may burn before the episode is over. Several NASA-funded scientists have helped the Brazilians respond to the disaster by providing daily summaries of fire detections made by satellite, aircraft, and ground observations.
These images from the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Terra satellite show a pattern of forest and farmland east of the city of Rio Branco before (top) and after (bottom) the peak of the 2005 agricultural burning season. The images are made from visible, shortwave, and near-infrared light detected by MODIS. Bright green is unburned forest, bright red is recently burned areas, and tan is cleared, but unburned land. Next to some burned fields, the forest appears dark green, or "bruised," probably indicating places where fires escaped from fields and burned into the forest understory.
NASA images by Jesse Allen (NASA Earth Observatory) and Jeff Schmaltz (MODIS Rapid Response), text courtesy of NASA's Earth Observatory.
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The cultivation of some of these crops in mountainous, watershed areas has adverse effects for the environment,
notably the alteration of water cycles and erosion. In Peru, the cultivation of coca plants (containing the basic
ingredient for cocaine) was so widespread in the Andean foothills during the 1980s and 1990s that Peruvian river flood cycles were altered
in some areas, making the high-water season unpredictable. The most serious environmental
concern (other than deforestation) stemming from the cultivation of coca is the dumping of chemicals (including
kerosene, sulfuric acid, acetone, and carbide) used to process coca leaves. However, stopping coca cultivation is
nearly impossible due to simple economics: no crop outperforms coca. The CIA claims that some 600,000 hectares of forest are cleared annually for coca and opium
poppy cultivation.
In some parts of the world, large-scale commercial agriculture takes up the majority of the productive floodplain and volcanic soils, while leaving smaller farmers little choice but to cut farmland from the rainforest. The ownership of these large commercial
farms is concentrated in the hands of a wealthy minority, who may benefit from tax incentives to leave some of their
land fallow and not fully employed at any given time. These large farm businesses generally do not employ large numbers of locals, though when they do, workers are
used seasonally for low wages. In recent years, grain production in Brazil and other Latin American countries has widely accelerated. However, most of the money ends up in the hands of a few large landowners who, in more marginal areas, have relied on subsidies to survive the harsh soil and climate conditions. Only through these handouts have these landowners been able to turn a profit.
Soy
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Soybean cultivation in South America. Map showing soybean distribution area in South America as of the year 2000. Rainforest and savanna ("cerrado") ecosystems in the Amazon are giving way to soya fields. Images courtesy of the Global Land Use Database at the University of Wisconsin.
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Soybeans have become one of the Brazil's most important crops in the Amazon, as well as in the nearby cerrado grassland ecosystem. Today soybeans are flourishing—since 1998, Brazil has added 30 million acres of soybeans, and American firms are aggressively expanding their presence in the Brazilian agricultural sector. Brazil will likely soon supplant the United States as the world's leading exporter of soybeans, at the expense of the forests and savannas of the Amazon basin.
Annual deforestation rates and annual soy expansion for states in the Brazilian Amazon 1990-2005. Note that the 1995-1996 and 1998-1999 years were negative and do not show up on the chart. Graphs based on Brazilian government data.
Total deforestation and area of soybean cultivation across states in the Brazilian Amazon. Overall soybean cultivation makes up only a small portion of deforestation, though its role is accelerating. Further, soybean expansion and the associated infrastructure development and farmer displacement is driving deforestation by other actors.
Note: some soybean farms are established on already degraded rainforest lands and neighboring cerrado ecosystems. Therefore it would be inappropriate to assume the area of soybean planting represents its actual role in deforestation.
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More on soybeans in the Amazon
Biofuels can reduce emissions, but not when grown in place of rainforests
(7/22/2008) Biofuels meant to help alleviate greenhouse gas emissions may be in fact contributing to climate change when grown on converted tropical forest lands, warns a comprehensive study published earlier this month in the journal Environmental Research Letters. Analyzing the carbon debt for biofuel crops grown in ecosystems around the world, Holly Gibbs and colleagues report that "while expansion of biofuels into productive tropical ecosystems will always lead to net carbon emissions for decades to centuries... [expansion] into degraded or already cultivated land will provide almost immediate carbon savings." The results suggest that under the right conditions, biofuels could be part of the effort to reduce humanity's carbon footprint.
Amazon timber industry declares ban on illegal logging
(7/18/2008) The Brazilian state of Pará today announced a ban on the sales of illegally logged timber from the Amazon rainforests.
Amazon deforestation forecast for 2008 revised downward
(7/17/2008) Deforestation in the Brazilian Amazon fell sharply in the month of May (1,096 square kilometers) compared to May a year-ago (1,222 square kilometers), according to preliminary satellite data announced by the country's environment minister on Tuesday. Brazilian Environment Minister Carlos Minc said a preliminary analysis by the government's National Space Research Institute (INPE) showed 1,096 square kilometers (423 square miles) of rain forest were cut down in May, down from 1,123 square kilometers (434 square miles) in April.
Biofuels, food demand may doom tropical forests
(7/14/2008) Rising demand for fuel, food, and wood products will take a heavy toll on tropical forests, warns a new report released by the Rights and Resources Initiative (RRI).
Amazon soy moratorium extended; may be expanded to other products
(6/23/2008) Soy crushers operating in the Brazilian Amazon have extended a two-year-old moratorium on the purchase of soybeans produced on rainforest lands deforested after 2006, reports Reuters.
More news on soy in the Amazon
Palm oil
The palm oil industry is an increasingly important driver of forest conversion in southeast Asia, especially Indonesia and Malaysia. Cultivation of oil palm, the world's most productive oil seed, has expanded in Indonesia from 600,000 hectares in 1985 to more than 6 million hectares by early 2007, and is expected to reach 10 million hectares by 2010. In Sabah and Sarawak (Malaysian Borneo), the area of plantations has increased from 186,744 hectares in Sabah and Sarawak in 1984 to 1,673,721 hectares at the close of 2003. Scientists say the use of palm oil biodiesel from plantations established on peat soils releases 8 to 21 times the emissions as conventional diesel fuel.
More on palm oil
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Chart showing annual palm oil production by Malaysia and Indonesia from 1964-2006. Click to enlarge.
Forest cover versus palm oil production in Indonesia.
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Biofuels can reduce emissions, but not when grown in place of rainforests
(7/22/2008) Biofuels meant to help alleviate greenhouse gas emissions may be in fact contributing to climate change when grown on converted tropical forest lands, warns a comprehensive study published earlier this month in the journal Environmental Research Letters. Analyzing the carbon debt for biofuel crops grown in ecosystems around the world, Holly Gibbs and colleagues report that "while expansion of biofuels into productive tropical ecosystems will always lead to net carbon emissions for decades to centuries... [expansion] into degraded or already cultivated land will provide almost immediate carbon savings." The results suggest that under the right conditions, biofuels could be part of the effort to reduce humanity's carbon footprint.
Orangutans persist in islands amid a sea of oil palm plantations
(7/17/2008) Orangutan are surviving in forest islands in a sea of oil palm plantations in Malaysia, reports a new survey by a government-backed conservation initiative. The finding underscores the need to protect critical forest areas for the endangered primates as forest continues to fall in southeast Asia at a rate that is the highest of any of the world's tropical forest regions.
Biofuels, food demand may doom tropical forests
(7/14/2008) Rising demand for fuel, food, and wood products will take a heavy toll on tropical forests, warns a new report released by the Rights and Resources Initiative (RRI).
Palm oil industry moves into the Amazon rainforest
(7/9/2008) Malaysia's Land Development Authority FELDA has announced plans to immediately establish 100,000 hectares (250,000) of oil palm plantations in the Brazilian Amazon. The agency will partner with Braspalma, a local company, to form Felda Global Ventures Brazil Sdn Bhd. FELDA will have a 70 percent stake in the venture. The announcement had been expected. Last month Najib said Malaysia would seek to expand its booming palm oil industry overseas. The country is facing land constraints at home.
Orangutan populations drop due to logging, expansion for palm oil
(7/3/2008) Orangutan populations have fallen sharply on the two islands where they still live, reports a new study published in the journal Oryx.
More news on palm oil
Sustainable Agriculture in the Rainforest
Review questions:
- How does large-scale agriculture damage the rainforest?
- Why are soybeans generally bad for the Amazon?
- Are palm oil-based biofuels a threat to rainforests?
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Continued: Cattle Pasture
Unless otherwise specified, this article was written by Rhett A. Butler [Bibliographic citation for this page]
Other pages in this section:
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Recent news
Biofuels can reduce emissions, but not when grown in place of rainforests
(7/22/2008) Biofuels meant to help alleviate greenhouse gas emissions may be in fact contributing to climate change when grown on converted tropical forest lands, warns a comprehensive study published earlier this month in the journal Environmental Research Letters. Analyzing the carbon debt for biofuel crops grown in ecosystems around the world, Holly Gibbs and colleagues report that "while expansion of biofuels into productive tropical ecosystems will always lead to net carbon emissions for decades to centuries... [expansion] into degraded or already cultivated land will provide almost immediate carbon savings." The results suggest that under the right conditions, biofuels could be part of the effort to reduce humanity's carbon footprint.
Orangutans persist in islands amid a sea of oil palm plantations
(7/17/2008) Orangutan are surviving in forest islands in a sea of oil palm plantations in Malaysia, reports a new survey by a government-backed conservation initiative. The finding underscores the need to protect critical forest areas for the endangered primates as forest continues to fall in southeast Asia at a rate that is the highest of any of the world's tropical forest regions.
Amazon deforestation forecast for 2008 revised downward
(7/17/2008) Deforestation in the Brazilian Amazon fell sharply in the month of May (1,096 square kilometers) compared to May a year-ago (1,222 square kilometers), according to preliminary satellite data announced by the country's environment minister on Tuesday. Brazilian Environment Minister Carlos Minc said a preliminary analysis by the government's National Space Research Institute (INPE) showed 1,096 square kilometers (423 square miles) of rain forest were cut down in May, down from 1,123 square kilometers (434 square miles) in April.
Biofuels, food demand may doom tropical forests
(7/14/2008) Rising demand for fuel, food, and wood products will take a heavy toll on tropical forests, warns a new report released by the Rights and Resources Initiative (RRI).
Birds face higher risk of extinction than conventionally thought
(7/14/2008) Birds may face higher risk of extinction than conventionally thought, says a bird ecology and conservation expert from Stanford University. Dr. Cagan H. Sekercioglu, a senior research scientist at Stanford and head of the world's largest tropical bird radio tracking project, estimates that 15 percent of world's 10,000 bird species will go extinct or be committed to extinction by 2100 if necessary conservation measures are not taken. While birds are one of the least threatened of any major group of organisms, Sekercioglu believes that worst-case climate change, habitat loss, and other factors could conspire to double this proportion by the end of the century. As dire as this sounds, Sekercioglu says that many threatened birds are rarer than we think and nearly 80 percent of land birds predicted to go extinct from climate change are not currently considered threatened with extinction, suggesting that species loss may be far worse than previously imagined. At particular risk are marine species and specialists in mountain habitats.
More news on rainforest agriculture
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