People have been deforesting the Earth for thousands of years, primarily
to clear land for crops or livestock. Although tropical forests are
largely confined to developing countries, they aren’t just meeting local
or national needs; economic globalization means that the needs and wants
of the global population are bearing down on them as well. Direct causes
of deforestation are agricultural expansion, wood extraction (e.g.,
logging or wood harvest for domestic fuel or charcoal), and infrastructure
expansion such as road building and urbanization. Rarely is there a single
direct cause for deforestation. Most often, multiple processes work
simultaneously or sequentially to cause deforestation.
biggest direct cause of tropical deforestation is conversion to cropland
and pasture, mostly for subsistence, which is growing crops or raising
livestock to meet daily needs. The conversion to agricultural land usually
results from multiple direct factors. For example, countries build roads
into remote areas to improve overland transportation of goods. The road
development itself causes a limited amount of deforestation. But roads
also provide entry to previously inaccessible—and often unclaimed—land.
Logging, both legal and illegal, often follows road expansion (and in some
cases is the reason for the road expansion). When loggers have harvested
an area’s valuable timber, they move on. The roads and the logged areas
become a magnet for settlers—farmers and ranchers who slash and burn the
remaining forest for cropland or cattle pasture, completing the
deforestation chain that began with road building. In other cases, forests
that have been degraded by logging become fire-prone and are eventually
deforested by repeated accidental fires from adjacent farms or pastures.
activities have dominated agriculture-driven deforestation in the tropics
to date, large-scale commercial activities are playing an increasingly
significant role. In the Amazon, industrial-scale cattle ranching and
soybean production for world markets are increasingly important causes of
deforestation, and in Indonesia, the conversion of tropical forest to
commercial palm tree plantations to produce bio-fuels for export is a
major cause of deforestation on Borneo and Sumatra.
poverty is often cited as the underlying cause of tropical
deforestation, analyses of multiple scientific studies indicate that that
explanation is an oversimplification. Poverty does drive people to migrate
to forest frontiers, where they engage in slash and burn forest clearing
for subsistence. But rarely does one factor alone bear the sole
responsibility for tropical deforestation.
State policies to encourage
economic development, such as road and railway expansion projects, have
caused significant, unintentional deforestation in the Amazon and Central
America. Agricultural subsidies and tax breaks, as well as timber
concessions, have encouraged forest clearing as well. Global economic
factors such as a country’s foreign debt, expanding global markets for
rainforest timber and pulpwood, or low domestic costs of land, labor, and
fuel can encourage deforestation over more sustainable land use.
Access to technology may
either enhance or diminish deforestation. The availability of technologies
that allow “industrial-scale” agriculture can spur rapid forest
clearing, while inefficient technology in the logging industry increases
collateral damage in surrounding forests, making subsequent deforestation
more likely. Underlying factors are rarely isolated; instead, multiple
global and local factors exert synergistic influences on tropical
deforestation in different geographic locations.
Another way to look at
deforestation is in terms of the percent of a country’s forest that was
cleared over time. By this metric, the island nation of Comoros (north of
Madagascar) fared the worst, clearing nearly 60 percent of its forests
between 1990 and 2005. Landlocked Burundi in central Africa was second,
clearing 47 percent of its forests. The other top five countries that
cleared large percentages of their forests were Togo, in West Africa (44
percent); Honduras (37 percent); and Mauritania (36 percent). Thirteen
other tropical countries or island territories cleared 20 percent or more
of their forests between 1990-2005.
Credit: NASA Earth