A large part of the world’s land is covered in forest of some kind, from the evergreen forests of Northern Canada and Russia to tropical forests of central Africa and the Amazon basin, about 31% of the planet’s land surface is covered by forests. These forests serve many crucial functions, including providing habitat for thousands of animal species, trapping carbon dioxide, and providing resources for people who live in or near them.
Causes of Deforestation:
The World Wildlife Fund mentions six main causes of deforestation. Some of them are familiar - illegal logging and clear cutting for palm oil plantations make the news sometimes - but other causes are less obvious. They estimate worldwide forest loss at 46,000 to 58,000 square miles per year. Overall, agriculture is a major reason for deforestation, and slash-and-burn agriculture is an easy way to clear some forest for planting.
Mining - We don’t typically think of mining as something that affects forests or farms because mines are mostly underground. However, much mining is done by digging huge pits in the ground or stripping to tops of hills and mountains. The mining companies cut trees to build roads, power plants, and railroad lines.
Harvesting wood for fuel - In many parts of Asia, Africa, and Latin America residents depend on wood for cooking and for heat, if they live in a cold climate. The effect of millions of people cutting branches and whole trees for wood adds up to a small, but significant, contribution to worldwide deforestation.
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Conversion to other uses - Most of the forest area lost to human activity has probably been due to agriculture. Palm oil, cassava, and soy cultivation are significant culprits. Sometimes people clear forests to provide better grazing land for livestock, mainly cows. It isn’t just food crops displacing forests either. Rubber and pulp, for paper, are two more industries that displace natural forests. Governments and private companies also clear the land for roads and new settlements.
Forest fires - Whether set on purpose, caused by an accident, or touched off by natural events like lightning strikes, fires destroy millions of acres of forest a year. Forests tend to recover from natural fires, but fires set by farmers or started by careless people are another matter.
Illegal and unsustainable logging - Illegal logging is a significant threat to forests from Brazil to Indonesia. Some logging firms clear-cut large sections of forest to feed the demand for lumber in Europe, China, and North America.
Climate change - Deforestation is a contributing factor in climate change, as well as a product of it. Hotter weather puts stress on plants. More importantly, changing rainfall patterns can make an area too dry for the remaining trees and other plants. Once the land has dried up, it cannot necessarily recover without human intervention. Loss of forests can also contribute to climate change because forest growth captures carbon dioxide.
Because forests are such important storehouses for carbon, their loss is a factor in climate change. There are other effects to cutting down forests and not replacing them too.
Effects of Deforestation:
National Geographic Magazine summarizes five primary effects of deforestation. The loss of trees causes several problems. In short, cutting or burning forests has a number of negative effects on soil, water, the climate, and the ecosystems they are part of.
Loss of biodiversity - According to National Geographic, 80% of the world’s plants and animals live in forests, and many cannot live elsewhere. With so many of the world’s plants and animals live in forests, that a significant reduction in that habitat, whether tropical rainforest or northern evergreen forest has an impact on biodiversity. Worse, many endangered plants and animals live only in a certain kind of forest habitat. Those species can be lost entirely or can become extinct in the wild very easily.
Climate change - Cutting down the trees also removes a mechanism to regulate the temperature in forested areas. Hotter days and cooler nights put additional strain on the remaining plants and animals. Growing trees trap a good deal of carbon dioxide. That function cannot be fully replaced by planting single crops, like soy or hemp. The plants are good at holding moisture, trees in particular. Without forest cover, deserts can advance and push out remaining plants and animals.
Loss of soil fertility - Forested land can be attractive for agriculture because it seems so fertile. In fact, this often isn’t so. The seeming fertility of a rainforest depends on the complex relationships between a variety of plant species. Clearing an area to plant soy or hemp just exposes soil that is high in nutrients at first. After a few growing seasons, the soil is exhausted and the farmers move on. The trees and brush in a forest help prevent soil from running off into lakes and rivers and polluting them.
Flooding - Forests absorb heavy rains that otherwise could run directly into rivers and streams. After a storm, or after several rainy days, a local river can rise to flood stage, even with forests taking up much of the water. Without greatly reduced forest cover comes greatly increased runoff and flooding. Because so much of the world’s population lives along rivers, indiscriminate cutting and burning of forests can be a real threat to lives and property downstream.
Water pollution - Clearing a forest also causes runoff into the water. The soil carries away nutrients and may pollute the water with agricultural chemicals. This would certainly happen if the forest is replaced with farm land. Water that should filter down through grass and soil into the water table runs off into nearby bodies of water, reducing the amount of ground water available later. The land that the forest once covered becomes drier and the soil becomes less and less suitable for growing food crops or for grazing. The issue of soil degradation is probably better known in the tropics, but it can be a concern anywhere that forests are clear-cut to make room for agriculture or take lumber.