Understanding tropical deforestation

Transcription

1 Understanding tropical deforestation By NASA, adapted by Newsela staff on Word Count 1,466 Level 1170L Two logging trucks on the Kalabakan-Sapulot-Road take heavy tropical timber logs to the log pond in Kalabakan, Indonesia. NASA A wide belt of forests of amazing diversity and productivity spans the earth's land surfaces right around the equator. Tropical forests include dense rainforests, where rainfall is abundant year-round; seasonally moist forests, where rainfall is abundant, but seasonal; and drier, more open woodlands. Tropical forests of all varieties are disappearing rapidly as humans clear the natural landscape to make room for farms and pastures, to harvest timber for construction and fuel, and to build roads and more developed areas. Although deforestation meets some human needs, it also has profound, sometimes devastating, consequences. These include social conflict, extinction of plants and animals, and climate change. And these challenges aren t just local. They are global. This article is available at 5 reading levels at 1

2 Causes Of Deforestation People have been deforesting the Earth for thousands of years, primarily to clear land for crops or livestock. Although tropical forests are largely located in developing countries, economic globalization means that the needs and wants of the global population are bearing down on them as well. Direct causes of deforestation include agricultural expansion, logging and wood harvest, and building things like roads and houses. The biggest direct cause of tropical deforestation is conversion to cropland and pasture, mostly for growing crops or raising livestock. The conversion to agricultural land usually results from multiple direct factors. For example, countries build roads to improve transportation of goods. The road development itself causes some deforestation. The new roads also provide entry to land that could not be accessed before. Logging 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 attract settlers who slash and burn the remaining forest for cropland or cattle pasture. In other cases, forests degraded by logging become fire-prone and are eventually deforested by repeated accidental fires. Day-to-day farming activities once dominated agriculture-driven deforestation in the tropics. But now, large-scale commercial activities play a major role in tropical deforestation. In the Amazon, for example, industrial-scale cattle ranching and soybean production for world markets are leading causes of deforestation. Underlying Causes Poverty drives people to migrate to forest frontiers, where they clear forests to farm. Tropical deforestation has many causes, though. Multiple scientific studies suggest there is more to it than poverty. This article is available at 5 reading levels at 2

3 State policies to encourage economic development, such as road and railway expansion projects, have caused significant deforestation in the Amazon and Central America. Global economic factors can also encourage deforestation over more sustainable land use. These include things like foreign debt or expanding global markets for rainforest timber and pulpwood. As long as people will pay for these products, there is an incentive to continue cutting down the forests. The availability of technologies that allow industrial-scale agriculture can spur rapid forest clearing. Meanwhile, inefficient technology in the logging industry increases damage in surrounding forests. Effects Of Deforestation Although tropical forests cover only about 7 percent of the Earth s dry land, they are likely home to about half of all species on Earth. Many species can only be found in small areas. Their specialization makes them more likely to go extinct. In addition to the species lost when an area is totally deforested, the forest that remains is more dangerous for the plants and animals still there. The edges of the fragments dry out and are hit by hot winds. People around the world buy products that come from rain forests. These include latex, cork, fruit, nuts, timber, fibers, spices, natural oils and resins, and medicines. Some of these products can be harvested in ways that do not hurt the forest. Many countries with tropical forests are working on programs that give people incentives for harvesting products sustainably. Why is it important to preserve the biodiversity of forests? The genes of plants, animals, fungi and bacteria that have not even been discovered yet may contain cures for diseases or the key to improving the yield and nutritional quality of foods. This article is available at 5 reading levels at 3

4 Effects On Soil With all the lushness and productivity that exist in tropical forests, it can be surprising to learn that tropical soils are actually very thin and lack healthful minerals. The soil comes from rock, and the heat and rain in the tropics washes away its minerals over time. Nearly all the vitamins and minerals of a tropical forest are in the living plants and the decomposing litter on the forest floor. When an area is completely deforested for farming, the farmer typically burns the trees and vegetation to create a fertilizing layer of ash. Vitamins and minerals are lost, flooding and erosion rates are high, and soils often become unable to support crops in just a few years. If the area is then turned into cattle pasture, the ground may become compacted as well, slowing down or preventing forest recovery altogether. Tropical forests are home to millions of native, or indigenous, peoples. Many rely on the forests to survive. Their cultural practices are often deeply tied to the forest and its resources. Deforestation in indigenous territories has sometimes triggered violent conflict. National and international governments and aid agencies struggle with questions about balancing human presence with conservation goals in tropical forests. The needs of indigenous peoples can often conflict with the demands of expanding rural populations and national economic development plans. Rainfall And Temperature Up to 30 percent of the rain that falls in tropical forests is water that the rainforest has recycled into the atmosphere. Water evaporates from the soil and vegetation, condenses into clouds and falls again as rain in a perpetual self-watering cycle. In addition to maintaining tropical rainfall, the evaporation cools the Earth s surface. In many computer models of the future climate, replacing tropical forests with a landscape of pasture and crops creates a drier, hotter climate in the tropics. Some models also predict that tropical deforestation will disrupt rainfall pattern far outside the tropics. In the Amazon alone, scientists estimate that the trees hold more carbon than 10 years worth of human-produced greenhouse gases. When people clear the forests, carbon stored in the wood returns to the atmosphere, increasing the greenhouse effect and global warming. Once the forest is cleared, the soils can become a large source of carbon emissions. It is not certain whether intact tropical forests are a net source or sink of carbon. Plants breathe, releasing carbon dioxide. In the Amazon, huge volumes of carbon dioxide escape from decaying leaves and other matter in rivers and streams during the rainy season. Undisturbed tropical forests may be nearly neutral with respect to carbon, but deforestation and degradation have the potential to turn the tropics into an even greater source. This article is available at 5 reading levels at 4

5 Rates Of Tropical Deforestation The Food and Agriculture Organization (FAO) of the United Nations produces a global forest resources assessment every five to 10 years. The FAO report is based on information provided by countries themselves. Many countries use satellites to measure deforestation. Because the ability of countries to accurately measure their forest resources varies, the estimates for some countries are likely more accurate than others. The FAO considers any area larger than 0.01 square miles with a minimum tree cover of 10 percent to be forested. This generous definition means that a significant amount of degradation can occur before the FAO categorizes an area as deforested. Still, the FAO assessment is the most comprehensive and widely used metric of global forest resources. The FAO report provides a grim picture. In 1990, 31.6 percent of global land area was forested. By 2015, it had dropped to 30.6 percent. There was a net loss of 500,000 square miles of forest between 1990 and That's nearly twice the size of Texas. However, the rate of annual net loss of forest has slowed a bit in recent years. Sustaining Tropical Forests On a local scale, organizations are working with forest communities to encourage low-impact agricultural activities. Parks and protected areas that draw tourists can provide employment and educational opportunities for local people. Many scientists are pushing to reconsider vast parks and protected areas for forest conservation. Scientists have shown that in the Amazon, far less deforestation occurs within territories managed by indigenous people than in parks and other protected areas. Inhabited forest reserves may be a more realistic strategy for preserving the majority of plants and animals in larger areas than parks alone. Finally, sustainable products are increasing in value in the global marketplace. This may give landowners reasons to adopt more forest-friendly practices and for governments to create and enforce forest-preservation policies. More countries are beginning to seriously tackle the problem of global warming. One way to help countries maintain forest ecosystems is to provide direct payments to tropical countries for protecting them. Healthy tropical forests are beneficial even for people outside the tropical countries. This article is available at 5 reading levels at 5

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7 Quiz 1 Read the paragraphs from the section "Effects On Soil." Tropical forests are home to millions of native, or indigenous, peoples. Many rely on the forests to survive. Their cultural practices are often deeply tied to the forest and its resources. Deforestation in indigenous territories has sometimes triggered violent conflict. National and international governments and aid agencies struggle with questions about balancing human presence with conservation goals in tropical forests. The needs of indigenous peoples can often conflict with the demands of expanding rural populations and national economic development plans. Which idea is BEST supported by these paragraphs? (A) (B) (C) (D) Conservation goals to reduce deforestation create problems for indigenous people. Government plans to address deforestation tend to do more harm than good to indigenous people. Large-scale economic activities that result in deforestation can put indigenous people at risk. Governments are incapable of helping indigenous people deal with deforestation. This article is available at 5 reading levels at 7

8 2 Read the paragraph from the section "Effects Of Deforestation." Although tropical forests cover only about 7 percent of the Earth s dry land, they are likely home to about half of all species on Earth. Many species can only be found in small areas. Their specialization makes them more likely to go extinct. In addition to the species lost when an area is totally deforested, the forest that remains is more dangerous for the plants and animals still there. The edges of the fragments dry out and are hit by hot winds. Which conclusion is BEST supported by this paragraph? (A) (B) (C) (D) If tropical forest deforestation is stopped, all plants and animals will be safe from extinction. More tropical forest species will be lost from deforestation than from future climate change. Deforestation poses a greater threat to animals that live in a tropical forest than their predators do. Some plant and animal species in tropical forests become extinct due to deforestation. 3 What purpose is served by describing the underlying causes of direct activities that result in deforestation? (A) (B) (C) (D) It suggests that the deforesting problem is complicated because there are many factors. It shows government policies are the only real reason deforestation occurs. It reveals effects of deforestation that have been studied but not yet reported. It compares multiple causes of deforestation that are often misunderstood. This article is available at 5 reading levels at 8

9 4 Read the paragraph from the section "Sustaining Tropical Forests." Many scientists are pushing to reconsider vast parks and protected areas for forest conservation. Scientists have shown that in the Amazon, far less deforestation occurs within territories managed by indigenous people than in parks and other protected areas. Inhabited forest reserves may be a more realistic strategy for preserving the majority of plants and animals in larger areas than parks alone. What does this paragraph accomplish? (A) (B) (C) (D) It shows scientists are especially concerned with indigenous people's rights. It suggests the strategy of creating parks to reduce deforestation was foolish. It indicates some strategies for reducing deforestation may be revised. It illustrates indigenous people know far more about deforestation than scientists do. This article is available at 5 reading levels at 9