{"id":143985,"date":"2014-02-06T16:20:33","date_gmt":"2014-02-06T18:20:33","guid":{"rendered":"http:\/\/revistapesquisa.fapesp.br\/?p=143985"},"modified":"2015-09-21T18:24:09","modified_gmt":"2015-09-21T21:24:09","slug":"invisible-threat","status":"publish","type":"post","link":"https:\/\/revistapesquisa.fapesp.br\/en\/invisible-threat\/","title":{"rendered":"Invisible threat"},"content":{"rendered":"
\"Floodlands

L\u00e9o Ramos<\/span>Floodlands account for 25% of the Amazon territoryL\u00e9o Ramos<\/span><\/p><\/div>\n

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 (km\u00b2) stretching across nine South American countries.\u00a0 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\u201420 million in Brazil alone. Its 6.6 million km\u00b2 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\u2019s largest freshwater reservoir, with about 20% of total available drinking water, and this makes it an important a factor in regulating the Earth\u2019s 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 Mamirau\u00e1 Institute for Sustainable Development, in his lecture at the BIOTA-FAPESP Education Conference Cycle in S\u00e3o Paulo on September 19, 2013.<\/p>\n

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\u2019s oldest and most serious problems. \u201cMany trees with wood of high commercial value provide essential food for a wide range of animals,\u201d Queiroz said.<\/p>\n

\"Helder

Eduardo Cesar<\/span>Helder Queiroz of the Mamirau\u00e1 Institute, and Maria L\u00facia Absy of InpaEduardo Cesar<\/span><\/p><\/div>\n

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<\/i> (Colossoma macropomum<\/i>). Another form of unsustainable exploitation involves catching piracatinga<\/i> (Calophysus macropterus<\/i>). Fishing for this species has stimulated unregulated, and sometimes illegal, hunting of alligators and of freshwater dolphins known as botos, <\/i>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. \u201cThis system of putting a price on biodiversity is seriously out of balance in Amazonia,\u201d he comments.<\/p>\n

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 km\u00b2 that encompasses eight states (Acre, Amap\u00e1, Amazonas, Par\u00e1, Rond\u00f4nia, Roraima and Tocantins in the North; Mato Grosso in the Central-West; and part of Maranh\u00e3o 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\u2019s indigenous population.<\/p>\n

\"Blue-crowned

L\u00e9o Ramos<\/span>Blue-crowned Motmot (Momotus momota<\/em>)L\u00e9o Ramos<\/span><\/p><\/div>\n

The Amazonian v\u00e1rzea<\/strong>
\nThe v\u00e1rzea <\/i>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 v\u00e1rzea<\/i> 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. \u201cMost of the v\u00e1rzea<\/i>, 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.\u201d<\/p>\n

Much of the v\u00e1rzea <\/i>area in the Amazon Region is flooded by whitewater rivers that originate in the Andes and carry rich sediments and nutrients.\u00a0 In these sections, the vegetation tends to be more abundant. \u201cBecause of this productivity and abundant natural resources, the v\u00e1rzea <\/i>forests suffer more consequences from constant human occupation,\u201d 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\u2014eight million people\u2014live in the Amazonian v\u00e1rzeas, <\/i>altering their environment on a daily basis. \u201cThe situation makes conservation of these forests more difficult, Queiroz pointed out. In addition, there are few areas protected by conservation units. \u201cEven outside the Arc of Deforestation, the Amazonian v\u00e1rzea <\/i>is the most heavily threatened environment,\u201d he noted.<\/p>\n