Human Threats to Rainforests—Fuelwood, Roads, Climate

Imperiled Riches—Threatened Rainforests

FUELWOOD/BUILDING MATERIAL

FAO estimates that 40 percent of the world (2.6 billion people) rely on fuelwood or charcoal as their primary source of energy for cooking and heating. Fuelwood consumption has increased 250 percent since 1960 (the world's population only increased by 90 percent since 1960).

The collection of fuelwood and building material from the rainforest remains an important cause of deforestation by settlers. For example, Honduras relies on the burning of fuelwood for 65 percent of the county's energy, while in some African nations the percentage is even higher. In the late 1990s the refugee camps, full of some 750,000 refugees, in eastern Zaire relied heavily on the collection of fuelwood from Virunga National Park, the mountain gorilla reserve. In just a few months over 20,000 acres of park were cleared for fuelwood and building material.

ROAD CONSTRUCTION

Roads in the Brazilian Amazon. Courtesy of Digital Earth.

The construction of roads to access logging, oil, and mining sites in the rainforest opens vast stretches of forest to exploitation by landless peasants who are responsible for the majority of rainforest destruction today. Generally these roads are funded by governments and development agencies, but some are also financed by private development interests. One of the most famous projects is the Trans-Amazonian highway in Brazil, which opened up the Roraima state to widespread invasion and deforestation by miners and colonists. A new road project in South America that will link Amazon outposts in Brazil to Pacific Ocean ports in Peru is of great concern to environmentalists and indigenous-rights groups. The road—known as the "transoceanic highway" -- runs through the state of Madre de Dios in southeastern Peru, an area of extraordinarily diverse rainforest.

HABITAT FRAGMENTATION

Habitat fragmentation is a serious threat to biodiversity and patches of forest worldwide (also see chapters 9 and 10). As great expanses of forest are increasingly chopped into smaller blocks, edge effects alter the the flora and fauna of forests. Fragmented patches of forest are subject to drying winds that increase the frequency of tree falls. Tree falls tear gaps in the canopy, destroying its function of moderating the humidity, temperature, and heat conditions of the forest floor. These changes affect the species that inhabit the forest patch, usually reducing diversity. Many rare species that dwell in the deep primary forest are unable to cope with the new conditions and are replaced by more common, weedier species. The drier forest conditions also mean that agricultural fires set in the surrounding scrubland and savanna are more likely to burn through the forest patch. During the Indonesian and Brazilian fires of 1997 and 1998, such forest patches went up in smoke at an alarming rate. Fragmented forests also suffer a loss of biomass—up to 36 percent—in the first few years after fragmentation.

New maps reveal the human footprint on Earth

CLIMATE CHANGE

Global climate change initiated by global warming is expected to have wide-ranging effects for tropical rainforests (also see chapter 9). Changes in weather patterns, rainfall distribution, and temperature will result in the conversion of rainforest into drier forest in some areas and the conversion of other forms of forests into tropical forest. Should sea levels rise, large tracts of rainforest and enormous areas of mangrove forest will be affected. Additionally, though tropical forests and their species have lived through significant climate changes in the past (Pleistocene and Holocene epochs), they have less resilience to climate change in the future due to fragmentation and degradation from human activities. In response to global climate change, communities will need to migrate, an action that will be more difficult because of habitat alteration and fragmentation.

A December 2005 simulation by the National Center for Atmospheric Research projects increased temperatures in the Amazon basin due to the conversion of moisture-producing forest into less-productive pasture and cropland.

Review questions:

What is an important energy source for rural poor in the tropics?
Why is forest fragmentation bad for rainforest biodiversity?
How will climate change effect the distribution of rainforests?

[full photo version]

Continued: Debt

Bibliographic citation for this page

Other pages in this section: