Everything is massive in scale in Amazonia, the largest remaining block of tropical forest on the Earth. The region covers an expanse of slightly more than 6.8 million square kilometers (km²) stretching across nine South American countries. Much of the region lies in Brazil, which hosts 69% of its forest coverage area. According to estimates, the Amazonian biome is home to nearly 25% of all living species on the planet, as well as 35 million people—20 million in Brazil alone. Its 6.6 million km² river basin, the largest in the world, plays a key role in providing drainage for several countries and in generating rainfall. It is the world’s largest freshwater reservoir, with about 20% of total available drinking water, and this makes it an important a factor in regulating the Earth’s climate and water balance. Despite such grandeur, it is small-scale changes such as opening up clearings for wood extraction that could present one of the main threats to conservation of the ecosystem, warned biologist Helder Queiroz, director of the Mamirauá Institute for Sustainable Development, in his lecture at the BIOTA-FAPESP Education Conference Cycle in São Paulo on September 19, 2013.
Generally speaking, he explained, the main threats to the Amazon Region today are associated with practices that lead directly or indirectly to loss of habitat and reduction of plant and animal populations. According to Queiroz, these threats can be divided into two groups. The first group comprises threats that significantly modify the landscape, such as clearance fires or infrastructure works to support the building of hydroelectric plants and roads. The second group consists of imperceptible changes in the landscape that, though smaller and barely detectable in satellite images, can quickly trigger significant local changes. In the long term, however, these threats could have an impact on the maintenance of regional biodiversity. One example of a hard-to-measure change is the opening of small clearings for selective extraction of wood, which constitutes one of the region’s oldest and most serious problems. “Many trees with wood of high commercial value provide essential food for a wide range of animals,” Queiroz said.
The construction of small dams, which alters the course of rivers and streams and inhibits the transport of sediments, also has a local effect on the ecosystem. Overfishing has already reduced stocks and populations of fish such as tambaqui (Colossoma macropomum). Another form of unsustainable exploitation involves catching piracatinga (Calophysus macropterus). Fishing for this species has stimulated unregulated, and sometimes illegal, hunting of alligators and of freshwater dolphins known as botos, whose meat is used as bait. Queiroz says that an alligator carcass that sells for R$100 can yield up to 300 kilograms of the fish, which is consumed in northeastern Brazil and exported to neighboring countries such as Colombia. “This system of putting a price on biodiversity is seriously out of balance in Amazonia,” he comments.
The greatest loss of natural environments is occurring in a region known as the Arc of Deforestation, which extends from the southern to the eastern Legal Amazon. It is an area of about five million km² that encompasses eight states (Acre, Amapá, Amazonas, Pará, Rondônia, Roraima and Tocantins in the North; Mato Grosso in the Central-West; and part of Maranhão in the Northeast). The Arc of Deforestation, delineated by the frontier of agricultural expansion that is converting vast expanses of forest into pastures, is home to about 56% of the country’s indigenous population.
The Amazonian várzea
The várzea regions of lowland terrain farther into the interior of the Amazon forest have also attracted the attention of the government as it develops ecosystem conservation strategies. Until recently, these areas were estimated to account for only 6% of the forest area. Today, according to Queiroz, the várzea regions are believed to comprise up to 25% of the forest. He explained that these areas are continually subject to flooding, and near the coast they are affected by tides that bring daily fluctuations in floodwater. “Most of the várzea, however, lies farther into the forest interior near the Amazon River and has an entirely unpredictable seasonal flood pattern that depends on the amount of rain that falls near the beds of the small rivers.”
Much of the várzea area in the Amazon Region is flooded by whitewater rivers that originate in the Andes and carry rich sediments and nutrients. In these sections, the vegetation tends to be more abundant. “Because of this productivity and abundant natural resources, the várzea forests suffer more consequences from constant human occupation,” he said. All of the large Amazonian cities and many of the small ones are located in these areas. At present, 75% of the local population—eight million people—live in the Amazonian várzeas, altering their environment on a daily basis. “The situation makes conservation of these forests more difficult, Queiroz pointed out. In addition, there are few areas protected by conservation units. “Even outside the Arc of Deforestation, the Amazonian várzea is the most heavily threatened environment,” he noted.
Sign of relief
Despite the scenario of apparent degradation, deforestation rates in the Amazon Region have been declining for the past eight years. According to Maria Lúcia Absy, a researcher from the National Institute for Amazonian Research (Inpa) who was one of the lecturers, there was an 84% reduction in the annual rates of deforestation in the Legal Amazon region between 2004 and 2012. From 2011 to 2012 the reduction was only 29%, according to data obtained through PRODES, a project designed to monitor the Brazilian Amazon forest using satellite images. The project is managed by the National Institute for Space Research (INPE), in partnership with the Ministry of the Environment (MMA) and the Brazilian Institute of the Environment and Renewable Natural Resources (IBAMA), with funding from the Ministry of Science, Technology and Innovation (MCTI) through its Amazonian Environmental Monitoring effort.
In addition to PRODES, the activities to monitor deforestation rates have another source of support based on satellite imagery: the Real-Time System for Detection of Deforestation (DETER), a quick monthly survey conducted since 2004 by INPE and the MCTI, also supported by the MMA and IBAMA. This system quickly provides monitoring agencies with the location of recently deforested areas. “Without a doubt, both PRODES and DETER are important tools for monitoring and controlling deforestation in the Amazon,” Absy asserted.
There are two possible reasons for the reduced deforestation, Queiroz observed. It could be attributed to the combined efforts of interministerial commissions created nearly 10 years ago to control the clearing of trees in the Amazon, which produced a series of government actions aimed at forest conservation. The other possible reason, says the biologist, may be related to Brazil’s economic growth over the last few years, “coupled with diversion of private-sector investments to activities less related to extractivism, which also may have contributed to this scenario.”
The two researchers agree on one point: that human activity in these regions needs to be managed properly so that due consideration is given to the production chains, which are highly important to the states in the North. But this must be done without causing significant impact on biodiversity and ecosystem conservation. “These production chains can account for up to 15% of the Gross Domestic Product (GDP) of some northern states,” Queiroz said. “It is not wrong to deforest an area for production purposes, as long is the area is not large. The mistake is in doing it in random fashion, without proper forest management methods and techniques,” Absy concluded.
Daniel das NevesSome years ago the Mamirauá Institute introduced forest management initiatives that have been producing significant results. Ten years later, as a result of well-managed extraction of wood species, the market values for softwood and hardwood have risen more than 250%. In addition, well-managed fishing practices that prevent overfishing and take into account species mating periods have helped to increase the size of the pirarucu (Arapaima gigas), a fish that is widely consumed locally. In recent years, the average size of the fish caught in managed waters has exceeded the minimum legal size of 150 centimeters, and fish stocks have grown by more than 300%. “As a result, there has been a 130% increase in average monthly income among fishermen,” Queiroz noted. But we need to broaden the scope of these efforts, he said. “At the end of the day, the problems in the world’s largest tropical forest are enormous.”
The BIOTA-FAPESP Education Conference Cycle is an initiative of the BIOTA-FAPESP program in partnership with Pesquisa FAPESP, focused on discussing the challenges involved in preserving Brazil’s principal ecosystems. The lectures, to be presented between now and November, are intended to present state-of-the-art knowledge generated by researchers throughout Brazil, aimed at improving the quality of environmental and science education for high school teachers and students in Brazil.Republish