The Amazon is home to some 40 percent of the world’s remaining tropical forest, which is disappearing at an increasing rate. Much of the forest that’s left is fragmented or otherwise degraded, leaving some species in isolated patches in which their prospects to reproduce and survive are grim.
Amazonia’s fate is a cause that has been taken up by environmentalists around the world, a factor that Brazilians and their government has seen as a mixed blessing. Saving a natural wonder that encompasses 58 percent of Brazil’s land mass and that borders upon eight other countries is a matter of national pride for many, but receiving instructions from foreigners about how to manage their country’s natural assets is generally taken as an insult.
And within Brazil, there are many competing economic interests making claims upon the natural resources of the Amazon forest. Much of the area is reserved for the indigenous peoples who live there, who have their different cultures, philosophies and economic aspirations that affect land uses, sometimes by strict conservationist policies and sometimes by heavy logging. There are millions of landless peasants in Brazil, yearning for a patch of land to farm and call their own. Many a middle or upper class family wants a little farm in the jungle for weekends and vacations. Brazil has the world’s largest cattle herd, which generates a constant demand for pasture land. Big-time agribusiness, which generates much of the foreign revenue that heavily indebted Brazil needs to meet its obligations, seeks to expand. A modernizing Third World economy seeks to connect its cities, and especially its major agricultural regions with its seaports, by expanding the national road network.
The cliche is some rich man slaughtering the Indians, bulldozing the trees and setting the whole thing on fire so that he can graze more cattle. It may be built around a grain of historical truth, but at much more than a casual fleeting glance the actual process of deforestation appears to be much more complicated and much less of a clear-cut moral issue. And then, how valid is the appearance?
The Smithsonian Tropical Research Institute’s Bill Laurance is studying the processes of Amazon deforestation, using technological resources like satellite photography and human resources such as an international team of graduate students. One of those grad students is McGill University’s Kathryn Kirby, who is working on her master’s thesis on the subject of deforestation. On January 6 Kirby spoke on the driving factors behind Amazon deforestation to those attending the Smithsonian Tropical Research Institute’s weekly science lecture series.
Referring to maps and aerial photographs, Kirby pointed out that the most deforested areas of Brazilian Amazonia are the southeast fringe and along roads and the Amazon River. But are the things that have gone on before good predictors of future trends? Kirby said that the current administration of Ignacio Lula da Silva seems to be carrying out policies that existed before he took office, but the government says that past abuses will not be repeated. Most major road projects in the Amazon, she added, involve the paving of existing roads rather than the cutting of new ones.
Looking back over Brazilian history since the European conquest, cattle ranching and small-time farming were the most important factors in Amazon deforestation.
In the 1960s and 1970s, Kirby pointed out, the military regimes of the time encouraged the expansion of cattle raising in the region and many large ranches were cut out of the forest. Still, a lot of small and medium-sized operators raise a few cattle, and because land prices are up and the threat of land invasions is constant, a lot of land owners clear land for grazing as a means to show the “effective use” of the property, which is an important factor in a legal defense of ownership rights.
The small-time slash-and-burn style of farming is unsustainable, even though the ashes from a burned-down forest make good fertilizer for a season or so. The people who use such methods rarely have the money for chemical fertilizers and thus generally move on to somewhere else, often selling the land they have cleared to wealthier farmers or ranchers.
A lot of the land concentration, especially in the dryer parts of the Brazilian Amazon, is for the benefit of the politically powerful soybean industry, which is pushing north from its southeastern base. This sector is in a relatively few hands, and its owners use agricultural chemicals and mechanized techniques that require relatively few laborers.
The soybean farmers are a relatively new but important factor in deforestation, and not only because they directly and indirectly clear vast tracts. Because of their political and economic power they are in a position to resist government policies designed to restrain deforestation. They also tend to find support when they advocate new roads through the forest to get their produce to world markets.
Using data from Brazilian government agencies --- not all of whose functionaries are happy to help foreigners studying Amazon land uses --- Kirby has attempted an empirical analysis that would lead to a reliable evaluation of the relative importance of the different factors behind Amazonian deforestation. Some of those data are in the form of satellite photography, as one feature of Brazil’s development is its own space program.
Looking from space at 50-square-kilometer “grid cells,” which are scanned for various factors like soil and rainfall as well a geographic realities like proximity to roads, rivers, population centers and previously cleared lands, Kirby has found that the single strongest predictor of deforestation is the presence of paved roads. In general, accessibility by road, proximity to a large population, the existence of a longer dry season and cleared land nearby are all factors that make a given piece of forested land more likely to be cut down.
Taking the historical view, Kirby found that the land use practices of the first settlers to enter a region tend to set trends that those who arrive later tend to follow. Taking a sociological view, she found that urban absentee landowners are more likely to deforest their farms than are people who live on the land they work.
The quality of farmland probably has little to do with deforestation, Kirby found. Soil fertility has hardly anything to do with it. High rainfall does make deforestation less likely, and is also a negative factor for the growing of grains and soybeans. However, the McGill student wasn’t able to say for sure whether the relationship between a long dry season and a higher deforestation rate is mainly because dryer areas are better for cash crops or because the longer the dry season, the longer the season for clearing land.
The studies that have been done of Amazon deforestation have their methodological drawbacks, Kirby noted. Attempts to view all of Amazonia tend to over-generalize, so more efforts need to be made at sub-regional analyses and looking at specific areas over time. Then trends change with time, skewing attempts to extrapolate what might happen in the future using data from the past and present. Finally, “agent-based” viewpoints, which have their own weaknesses and disadvantages in comparison with empirical studies, are nevertheless worthwhile at discovering the local and socio-economic aspects of deforestation.
The main policy conclusions that Kirby draws from her studies are that roads tend to lead to deforestation; that the dryer areas of Amazonia need more protection than they now get; that when demand for land is high the quality of the land in danger of deforestation becomes less of a factor; and that the indigenous people whose protected lands comprise roughly one-third of the Brazilian Amazon need to be taken into account in regional conservation efforts.
Also in this section:
Genome pioneer J. Craig Venter speaks in Panama
Putting the causes of Amazonia's deforestation in perspective
Long distance dispersal of species
Mussel glue
Gene-spliced crops use more pesticides
