344 Agricultural Revolutions and Change
services are lost. More often, however, there is no single ‘best bet’, but instead there
is a range of trade-offs across land-use alternatives regarding environmental and
agricultural development objectives.
Who are the small-scale slash-and-burn farmers?
The number of people who depend on shifting cultivation for their livelihoods has
for decades been estimated at about 250–300 million (Hauck, 1974; Myers, 1994).
Recent georeferenced population and farming system data suggest that the num-
bers are an order of magnitude lower. Dixon et al (2001) report that 37 million
people, or 2 per cent of the agricultural population of the tropics, practise some
form of shifting cultivation in about 1 billion ha or 22 per cent of the tropical land
area. This is the area of influence, but only a small fraction of that is under actual
cropping or fallows. These numbers do not include people practising more intense
systems in the humid tropics that were originally established by slash-and-burn
practices. The number of people involved in these other crop-based, tree-based or
pasture-based slash-and-burn systems is several times that of shifting cultivators
(Dixon et al, 2001).
Deforestation by slash-and-burn farmers is a response to underlying root
causes. Population growth is naturally viewed as a main driver of deforestation,
and economic growth often is viewed in the same vein. But no direct relationship
between deforestation and population growth or economic growth has been found.
Myers (1991) noted that whereas the population of forested tropical countries
increased by 15–35 per cent in the 1980s, deforestation expanded by 90 per cent
during the same period. The recent analysis by Geist and Lambin (2002) shows
that in-migration to the forest margins is a much larger factor in deforestation than
high internal population growth. Brown and Pearce (1994) obtained inconclusive
results when attempting to relate gross domestic product (GDP) growth rates,
foreign debt and population growth with deforestation in tropical countries. Rudel
and Roper (1997) found that in tropical countries with large forested areas, defor-
estation increases with increasing GDP, whereas in countries with mainly forest
fragments, increasing GDP decreases deforestation.
Whereas traditional, indigenous people practise shifting cultivation, many (in
some cases most) of the people practising slash-and-burn agriculture are migrants
from other parts of their country who seek a better life at the forest margins. In
some countries, large numbers of migrants to the forest margins come as part of
government-sponsored colonization programmes aimed at transmigrating poor
people from densely populated areas to the forest frontier, particularly in Brazil
and Indonesia (Hecht and Cockburn, 1989; Kartasubrata, 1991). Others are
spontaneous migrants who, acting independently with little or no government
support, follow the opening of roads and logging trails. Planned and spontaneous
migrations of poor people from crowded regions such as Java, the Andes and
north-eastern and southern Brazil have undeniably contributed to deforestation.
Opening of roads into primary forests such as the Belém-Brasília, Transamazônica