The trees are not expected to regrow. Forest degradation measures a thinning of the canopy — a reduction in the density of trees in the area — but without a change in land use.
Thanks to satellite imagery, we can get a birds-eye view of what these drivers look like from above. In the figure we see visual examples from the study of forest loss classification by Philip Curtis et al.
Commodity-driven deforestation and urbanization are deforestation : the forested land is completely cleared and converted into another land use — a farm, mining site, or city. The change is permanent. There is little forest left. Forestry production and wildfires usually result in forest degradation — the forest experiences short-term disturbance but if left alone is likely to regrow. The change is temporary. This is nearly always true of planted forests in temperate regions — there, planted forests are long-established and do not replace primary existing forests.
In the tropics, some forestry production can be classified as deforestation when primary rainforests are cut down to make room for managed tree plantations. But it can bridge between deforestation and degradation depending on the timeframe and permanence of these agricultural practices. In their analysis of global forest loss, Philip Curtis and colleagues used satellite images to assess where and why the world lost forests between and The breakdown of forest loss globally, and by region, is shown in the chart.
Just over one-quarter of global forest loss is driven by deforestation. We see massive differences in how important each driver is across the world. In Latin America and Southeast Asia in particular, commodity-driven deforestation — mainly the clearance of forests to grow crops such as palm oil and soy, and pasture for beef production — accounts for almost two-thirds of forest loss.
In contrast, most forest degradation — two-thirds of it — occurs in temperate countries. Centuries ago it was mainly temperate regions that were driving global deforestation [we take a look at this longer history of deforestation in a related article ].
They cut down their forests and replaced it with agricultural land long ago. But this is no longer the case: forest loss across North America and Europe is now the result of harvesting forestry products from tree plantations, or tree loss in wildfires. Africa is also different here.
Forests are mainly cut and burned to make space for local, subsistence agriculture or for fuelwood for energy. Africa is also an outlier as a result of how many people still rely on wood as their primary energy source.
Noriko Hosonuma et al. Note that in this study, the category of subsistence agriculture was classified as a deforestation driver, and so is not included. With increasing development, urbanization and access to other energy resources, Africa will shift from local, subsistence activities into commercial commodity production — both in agricultural products and timber extraction.
The world loses almost six million hectares of forest each year to deforestation. The breakdown of deforestation by region is shown in the chart.
In a related article we look in much more detail at what agricultural products, and which countries are driving this. As we saw previously, this deforestation accounts for around one-quarter of global forest loss. Urbanization, the other driver of deforestation accounts for just 0. But there is good reason to make this our primary concern. Philipp Curtis and colleagues make this point clear.
At their Global Forest Watch platform they were already presenting maps of forest loss across the world. But they wanted to contribute to a more informed discussion about where to focus forest conservation efforts by understanding why forests were being lost. Why should we care most about tropical deforestation? There is a geographical argument why the tropics? Tropical forests are home to some of the richest and most diverse ecosystems on the planet. Whether we look at the distribution of endemic mammal species , bird species , or amphibian species , the map is the same: subtropical countries are packed with unique wildlife.
Habitat loss is the leading driver of global biodiversity loss. Tropical forests are also large carbon sinks, and can store a lot of carbon per unit area. Deforestation also results in larger losses of biodiversity and carbon relative to degradation.
Degradation drivers, including logging and especially wildfires can definitely have major impacts on forest health: animal populations decline, trees can die, and CO 2 is emitted.
But the magnitude of these impacts are often less than the complete conversion of forest. They are smaller, and more temporary. Deforestation tends to occur on forests that have been around for centuries, if not millennia. Cutting them down disrupts or destroys established, species-rich ecosystems. The biodiversity of managed tree plantations which are periodically cut, regrown, cut again, then regrown is not the same. That is why we should be focusing on tropical deforestation.
But, it would be wrong to think that the only impact rich countries have on global forests is through changes in their domestic forests. They also contribute to global deforestation through the foods they import from poorer countries.
Today, most deforestation occurs in the tropics. To investigate this question, researchers Florence Pendrill et al. In the map we see the net deforestation embedded in trade for each country.
Net importers of deforestation shown in brown are countries that contribute more to deforestation in other countries than they do in their home country. The consumption choices of people in these countries cause deforestation elsewhere in the world. For example, after we adjust for all the goods that the UK imports and exports, it caused more deforestation elsewhere than it did domestically.
It was a net importer. Brazil, in contrast, caused more deforestation domestically in the production of goods for other countries than it imported from elsewhere. It was a net exporter. Although there is some year-to-year variability [you can explore the data use the timeline on the bottom of the chart from to ] we see a reasonably consistent divide: most countries across Europe and North America are net importers of deforestation i.
Most deforestation occurs for the production of goods that are consumed within domestic markets. Many rich countries are driving deforestation in other parts of the world, but are regrowing forests domestically. How do these two measures compare? Are they causing more deforestation elsewhere than they are regenerating in forests at home? Imagine some temperate country was responsible for the deforestation of 25, hectares in tropical countries but was restoring its own forests at a rate of 50, hectares per year.
On balance, it would still have a positive impact on the size of global forests; its net contribution would be increasing forest area by 25, hectares. Not all forest is equal. Tropical forests are often more productive than temperate forests, meaning they store more carbon. They are also richer sites of biodiversity. Hence, we should keep in mind that forest area is not the only aspect that matters — where that forest is and how rich in life it is matters too.
It would be good if there was data available that would capture these additional aspects. We manage to capture some of these differences in carbon in our related article on deforestation emissions embedded in trade. Without reliable metrics that capture all of these differences, we will have to stick with total changes in forest area for now.
But we should keep these important aspects in mind when comparing forest losses and gains. In the chart we see the comparison between the change in domestic forest area, and deforestation driven by imported goods. Since there is often year-to-year variability in deforestation or reforestation rates, this is shown as the five-year average. On the x-axis we have imported deforestation. The grey line marks where the area of domestic regrowth of forests is exactly equal to imported deforestation.
Countries that lie along this line would have a net-neutral impact on global forests: the area they are causing to deforestation overseas is exactly as large as the area they are regrowing at home. Countries which lie above the grey line — such as the United States, Finland, China — restore more forest each year domestically than they import from elsewhere. More than four times as much. On balance, they add to the global forest stock.
After seeing this data, people might argue that we should cut back on trade. If poorer countries are cutting down forests to make food for rich consumers, then we should just stop trading these goods. But the solution is not so simple. There are other aspects to consider. International trade is important for socioeconomic development. Many farmers rely on international buyers to earn a living and improve their livelihoods.
Not only would this be bad for people, it might also be bad for forests. One of the reasons poorer countries clear forest to make room for farmland is that they achieve low crop yields. If you struggle to increase crop yields but want to produce more food, then expanding your agricultural land is the only option. This often comes at the cost of forests. Improvements in agricultural productivity tends to both drive and follow economic growth.
International trade plays an important role in this growth, and may allow farmers to see the yield gains they need to produce more food using less land. One option is to adopt stricter guidelines on what suppliers to source from, and implementing zero-deforestation policies that stop the trade of goods that have been produced on deforested land.
Another way that richer countries can contribute is by investing in technologies — such as improved seed varieties, fertilizers and agricultural practices — that allow farmers to increase yields. The first step in doing this is for rich countries to monitor their deforestation impacts overseas more closely. They should keep their domestic reforestation targets in perspective with their net impact on global forests. Brazil and Indonesia alone account for almost half.
This might put the responsibility for ending deforestation solely on tropical countries. But, supply chains are international. What if this deforestation is being driven by consumers elsewhere? Many consumers are concerned that their food choices are linked to deforestation in some of these hotspots.
Cutting down trees required no advanced technology. The earliest people could use their stone or flint axes to fell trees or fire to clear large expanses. As civilization advanced, trees were cut down first for agricultural use and then for increased urbanization. The steady growth of population in the European forests from to B. The situation was similar for all continents, China, Africa and the Americas, with increased population over the next several millennia.
The invention of metal, saws and then power saws greatly accelerated the ability to clear land. Since the Industrial Revolution in the s, forests have been exploited worldwide. According to Michael Williams in his article in "History Today," in central European Russia, for example, 67, square kilometers 16,, acres of forests were cleared between the end of the 17th century to the start of the 20th century.
The American pioneers pushed forward into the West, and cutting trees was an integral part of everyday life. Approximately , square kilometers--an astounding million square miles--of forests were felled just by , and nearly million square miles by The most well-known deforestation has occurred since The softwood forests now meet the needs of today's societies. However, the severe problem is the major population explosion in the tropics.
The earth's largest rain forest is located in the 1. The basin includes a huge variety of plants and animals and thousands of different kinds of trees. UCS estimates that an area the size of Switzerland 14, square miles, or 38, square km is lost to deforestation every year. Natural fires in tropical forests tend to be rare but intense. Human-lit fires are commonly used to clear land for agricultural use.
First, valuable timber is harvested, then the remaining vegetation is burned to make way for crops like soy or cattle grazing. In , the number of human-lit fires in Brazil skyrocketed. Many forests are cleared to make way for palm oil plantations.
Palm oil is the most commonly produced vegetable oil and is found in half of all supermarket products. It's cheap, versatile and can be added to both food and personal products like lipsticks and shampoo. Its popularity has spurred people to clear tropical forests to grow more palm trees. Growing the trees that produce the oil requires the leveling of native forest and the destruction of local peatlands — which doubles the harmful effect on the ecosystem.
Forests can be found from the tropics to high-latitude areas. Forests provide more than a home for a diverse collection of living things; they are also an important resource for many around the world. In countries like Uganda, people rely on trees for firewood, timber and charcoal. Families send children — primarily girls — to collect firewood, and kids have to trek farther and farther to get to the trees.
Collecting enough wood often takes all day, so the children miss school. The UN's State of the World's Forests report found that over half the global population relies on forested watersheds for their drinking water as well as water used for agriculture and industry. Deforestation in tropical regions can also affect the way water vapor is produced over the canopy, which causes reduced rainfall.
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