Over the past twenty years, the fight has been on to save the Amazon and to protect its Indian lands. Pertinent in this struggle is the construction of the last sector of the BR-364 Road which would give the general population, as well as the timber industry, increased access to the Amazon and its wild resources.
Some of the greatest environmental and geological studies of the Amazon Basin to date have not been made from the ground but through the use of remote-sensing technology. Many specialists have long recognized the need for classifications of the vast biographical domain of the greater Amazon Basin. Deforestation is clearly contributing to the build-up of CO2 in the atmosphere, yet the actual amount of deforestation for a long time was largely unknown. It was found that no one system of remote sensing could provide the answers. Therefore both spaceborne and airborne radar images were acquired of portions of the Middle and Upper Amazon Basin in the State of Amazonas and the Territory of Roraima. The radar image data sets were obtained not only by Shuttle Imaging Radar B (SIR-B) in 1984, but by SIR-A in 1981 and by Radambrasil which operated from 1970 to 1985. The radar device used was able to penetrate clouds and the jungle canopy to reveal the surface features below. Radar has proved to be an effective supplement to Landsat and NOAA observations because of persistent cloudiness in the tropics. Remote-sensing radar can reveal features such as agricultural fields, urban areas, mountain ranges, and water surfaces.
Radambrasil mappings were compiled into 38 volumes of between 300 and 500 pages each. Radambrasil used a research airplane to take radar photos that covered a circular area of 37 kilometers in diameter. An altimeter registered the changes in altitude, but the plane attempted to maintain itself at 11 kilometers above the ground. For SIR-A and SIR-B data which was acquired from NASA's Shuttle flights, wavelengths from the radar system on board was set to 23.5 cm. SIR-A had a standard 50-kilometer swath width. SIR-B swath varied (20-50 kilometers) depending on the orientation of the antenna and with the bit rate and the variable antenna depression angle. The Amazon Basin is so massive that it would require approximately 400 Landsat scenes unless a sampling strategy was adopted.
In comparison, Radambrasil used a depression angle of 7-25 degrees as opposed to the 37-43 degrees depression angle used on SIR-A. A depression angle is the angle from the airplane, measured horizontally down to the surface, whereas incidence angle is the angle from the ground up which is complementary. Radar pulses that strike a horizontal surface at large depression/small incidence angles produce strong return echoes, while pulses that strike the same surface at smaller depression/larger incidence angles produce weaker radar returns. Differences thus are analyzed between the angle of the radar system and variations in surface relief and roughness.
The rate at which the backscatter decreases with increasing incidence angle is governed primarily by the physical characteristics of roughness, slope, dielectric constant, and moisture on the surface. As a general rule, a rougher surface will produce a stronger radar return than a smoother surface at incidence angles greater than 30 degrees. In some cases, the Radambrasil image showed clearer drain angle patterns because at relatively large incidence/small depression angles a greater shadowing effect occurs . This clarity is also effected by the closer proximity of the radar.
However, the lower depression angle sometimes failed to penetrate the jungle canopy. In the area of the Rio Negro, the flood-plain is also clearly distinguished and outlined showing contrast in image tone by the Shuttle radar, but not visible except for some relief information on Radam (Projecto Radar da Amazona) images due to the low depression angle. There is also no contrast along the length of the drainage to indicate flooded conditions on the Radam image, but appears on SIR-A as a cut-back condition. Similarly, the alluvial forest by the rivers Santa Helena and Taxidermista is completely indistinguishable by Radam and there is little or no contrast with vegetation from each side of the floodplain. At the much larger depression angle used on the SIR-A, the alluvial forest appears very bright in marked contrast to the forest on each side of the floodplain.
Taking into consideration variables such as time of day, incidence angle, etc. it is theorized that in particular regions of vegetated areas (excluding swampy areas) SIR-A brightness tends to increase with the vegetation index. Uncut areas are textually rough and, therefore, had a moderately strong radar return. Recently cleared regions showed increased spectral reflection, but older cut areas used for pasture land or vegetation were less bright due to the dielectric effect in wet regions, or because abandoned, previously cleared areas often have a rougher texture than even the primary forests, and are less efficient volume scatterers, showing a stronger return signal.
SIR-B has multiple angle imaging capabilities and therefore can collect pictures using a greater range of depression angles (from 30-75 degrees) so they can be used to differentiate surface materials on the basis of their roughness characteristics in much the same way that Landsat imagery collects information in multiple spectral channels to identify materials on the basis of the way they reflect sunlight.
SIR-B data experienced technical problems while flying over the area, but it showed forest clearing near Alta Floresta and Sinop in northern Matto Grosso. Near Sinop, some 200 farming plots were evident. They are generally long, in lattice-like patterns, and in narrow clearings parallel to one another. Most plots are smaller than 200 hectares indicating small operations of family farmers. In contrast, there are several clearings of 6000 hectares. Clearings of such a large scale usually are for commercial cattle grazing. It is becoming more essential that information on vegetation structure and regrowth be available to help separate primary forest from secondary regrowth.
Thus, scientists have been able to witness through remote-sensing, which produces both two and three -dimensional pictures, the first-hand destruction of massive hectares of forests robbing nature of the last ecosystems for the survival of the Indian people. There is no doubt that large-scale environmental changes are being created by population influx and land development. Computer simulations based on extensive historical data suggest the Amazon's rainfall can be expected to decline radically as drainage and deforestation proceed; then as deforestation proceeds, reforestation becomes nearly impossible.
Brasil's former Minister of the Environment, Dr. Jose Lutzenberger, was the visionary who saw the role of interdependence between the Amazon and the world. His plan was for education, research and protection policies to create a realistic authority over environmental units in each of Brasil's twelve government ministries to form a "consensus strategy" for long-range preservation of both land and wildlife, but before long he was displaced from his position.
Reacting to worldwide concern over the devastation of the rainforest, many claim there is no need to worry . After all, burning forests in Amazonia only account for less than 20% of the total increase in atmospheric carbon dioxide (according to Prof. A. Goldemberg, University of Sao Paulo, Brasil). However, the burning of the rainforest is doing more than just increasing carbon dioxide. The Amazon is the "great heat factory of the world"with a daily energy turnover equal to some six million atomic bombs. One of the great ironies of the modern industrial society with its remote-sensing technologies is that we can now see planet Earth as a whole—as a living biosphere. Yet, down here, we continue to behave as if we were blind.
Looking at the Amazonia from a satellite perspective, we see that the air masses, as shown by cloud movements, travel into central South America from the Atlantic, go west and hit the mountain chains of the Andes. There the flow splits into several branches. The central part rises over the mountains into the Pacific and continues west along the Equator, roughly following the convergence of the warm northern sea current, El Nino, with the cold Humboldt stream that comes from the South. These are systems of interconnected ocean streams and air streams which are responsible for the incredible richness of life in and above the waters of the west coast of South America and where in the last two decades we have seen the serious "flip-overs" of weather that have caused overnight collapse of the fishing industry.
However, according to Lutzenberger, the air currents over the Amazon do not only affect South America. The currents connected with El Nino effect the weather pattern over Central and Southern Africa. Moreover, the air masses over the Amazon work like a giant vortex and spawn off air currents that are capable of traveling as far north as the eastern coast of North America which in turn merge with the Gulf Stream air which reaches and penetrates Northern and Central Europe and may be the cause of the "green vegetation" in northern Norway.
What will happen if the Brasilian rainforest disappears? The forest makes its own climate and is the result of that unique climate. What if devastation continues at the present rate? Most everything could be gone by the year 2025 AD. A hundred thousand square kilometers of primeval forest are cleared every year the results of destruction grow exponentially. Land the size of Portugal is slashed and burned every year. And the end will inevitably be: (1) a change in weather, (2) an increase of drought and desert, and (3) massive starvation for many peoples, regardless of background and world economics. With large land parcels being given away for exploitation, there is absolutely no way, even with Radam surveys, to oversee clearance. At the present time, 100 tons of topsoil are lost per hectare each year. The forests that are destroyed will take a thousand years to regenerate. With their destruction goes the refugia of a species diversity entirely preserved from the early periods of evolution—the Pleistocene era in our "present" time: with color morphs, strange and beautiful speciations, butterfly wings of color.
All of this is being steadily destroyed, and there is human tragedy as well. At least 87 Indian tribes have become extinct this century. Anthropologists have seen an overall Amazonian aborigine population decrease over the past 500 years from an estimated 6.8 million to the present 125,000. Anthropologist Emilio Moran cites disturbing research indicating the decline of the Parakana and Nambiquara indigenous groups within very short periods of time due to the influences of outside companies, ranchers, and road workers whom the Indians call the "termite people."
As highways and small farmers who are simply trying to create a livelihood intensify their own slash-and -burn techniques throughout the Amazon basin—and more and more ruropoli (frontier family villages) of some 48-1000 people spring up in various locations throughout the Amazon—the forests are razed, the inroads flooded, the Malaria vector is strengthened, intense soil erosion occurs, and the river fish species die out. The tragedy is that most of these small family plots created by hundreds of thousands of new inhabitants are only able to sustain crops for a limited number of years because of the rainforest terrain. Therefore, these farmers must move on and find new land to utilize. So what happens to their old plots of land? They become wastelands with small brush, because the original trees cannot grow back due to their root structures and because the soil has been destroyed and removed.
In the wake of vast devastation throughout the Amazon, only now has the revelation of global atmospherics impressed biologists. The Amazon is the critical link in the Earth's carbon dioxide clearing house. Furthermore, Amazonian Indians and forest species possess the richest repository of native wisdom and potential medical, and technological plant products of any other region of the planet. But the metaphor of human disruption—since the sixteenth century—is fully at work in Brasil. The country is the vortex of ecological imperialism and new deforestation. A generation of embattled conscience has arisen in Central and South American writers who have responded to the political and moral crises with an anguished outpouring due to the mismanagement of such critical factors as: population growth, political agendas, and regional economics. Nobel Prize winner Garcia Marquez (The Autumn of the Patriarch) and Vargas Llosa (The War of the End of the World) are but a few of the many testimonies of this anguish.
Our time has now come to work for new cooperation in this and other critical environmental regions. Our species is the only one to lay claims to being able to influence the make up of the natural world. We long ago drew up the battle lines. Today, that struggle is most dangerously pronounced in the tropics, where soil is in short supply and human food is at a premium. The Amazon contains some 550 million hectares of rain forest, 3.5 million square kilometers, nearly half of the Earth's water moisture, easily a million plant and animal species. In but 2 hectares of Amazon forest, 173 floral species have been discovered on a base of 900 metric tons of living biomass. In short, for several thousand years, life has been fashioned according to its evolutionary laws and in the Amazon basin archaeological relics suggest an early habitation at the mouth of the Amazon dating back as far as 5000 years. As a part of Eden on earth, its destruction may also signify the end of life as we know it. It is our time to make the change to work together to expand the lifetime of the Amazon Basin in Brasil—so that there would be no end of real civilization, but a wise and practical preparation for the opening of the high frontier in meeting with other cultures and cosmic civilization in the 21st century.