The drivers of tropical deforestation have shifted in the early 21st century to hinge on growth of cities and the globalized agricultural trade, a new large-scale study concludes.
The observations starkly reverse assumptions by some scientists that fast-growing urbanization and the efficiencies of global trade might eventually slow or reverse tropical deforestation. The study, which covers most of the world’s tropical land area, appears in this week’s early edition of the journal Nature Geoscience.
Deforestation has been a rising concern in recent decades, especially with the recognition that it may exacerbate climate change. Studies in the late 20th century generally matched it with growing rural populations, as new roads were built into forests and land was cleared for subsistence agriculture. Since then, rural dwellers have been flooding into cities, seeking better living standards; 2009 was recorded as the first year in history when half of human lived in urban areas. Large industrial farms have, in turn, taken over rural areas and expanded further into remaining forests, in order to supply both domestic urban populations and growing international agricultural markets, the study suggests.
“The main drivers of tropical deforestation have shifted from small-scale landholders to domestic and international markets that are distant from the forests,” said lead author Ruth DeFries, a professor at the Earth Institute’s Center for Environmental Research and Conservation. “One line of thinking was that concentrating people in cities would leave a lot more room for nature. But those people in cities and the rest of the world need to be fed. That creates a demand for industrial-scale clearing.”
DeFries and her colleagues analyzed remote-sensing images of forest cover across 41 nations in Latin America, Africa and Asia from 2000-2005, and combined these with population and economic trends. They showed that the highest forest losses were correlated with two factors: urban growth within countries; and, mainly in Asia, growth of agricultural exports to other countries. Rural population growth was not related.
In recent years, tropical countries have been supplying growing amounts of palm oil, soybeans, sugar, meat and other processed products to distant markets abroad. Not all the products are used for food; palm oil and sugar in particular are also being converted into biofuels. Furthermore, said DeFries, as small farmers within tropical nations move away to become city dwellers, they may actually use more resources from the countryside, not less. This is because those living in cities have higher incomes—the reason most moved there to begin with—and thus tend to consume more processed foods and animal products. Pastures needed to produce meat, and large plantations and other facilities that turn out other products, in turn, require land. “Collectively, these results indicate a shift from state-run road building and colonization in the 1970s and 1980s to enterprise-driven deforestation,” says the study.
Hot spots of industrial-scale clearing include Brazil, Indonesia and Cambodia—countries that, unlike many others, still have considerable forests left to clear. The trend has not reached some forested parts of Latin America, such as Surinam or Guyana, which also have large tracts of remaining forest. Almost 60% of remaining forests occur in areas where net agricultural trade, percent of products exported, and urban growth are all relatively low. But as demand for products grows, these areas are likely to see increased pressure, the study says. According to projections by the United Nations, nearly all population growth in the next 40 years will take place in cities, and some two-thirds of people will live there by 2050.
DeFries said that some initiatives aimed at halting deforestation need to be quickly shifted. For instance, some policies that focus on getting small landowners to conserve forests—a popular mechanism among governments and nonprofits at the moment—“may not be all that productive without a focus on large-scale clearing as well,” she said. “Governments will have to look at policies that intensify yields on existing high-yield fields—not clear more land,” she said.
The other authors of the study are Columbia University ecologist Maria Uriarte; ecologist Thomas Rudel of Rutgers University; and Matthew Hansen of South Dakota State University.
Kevin Krajick | EurekAlert!
Water - as the underlying driver of the Earth’s carbon cycle
17.01.2017 | Max-Planck-Institut für Biogeochemie
Modeling magma to find copper
13.01.2017 | Université de Genève
Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.
While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...
Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales
Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...
Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.
As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...
At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).
Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...
Many pathogens use certain sugar compounds from their host to help conceal themselves against the immune system. Scientists at the University of Bonn have now, in cooperation with researchers at the University of York in the United Kingdom, analyzed the dynamics of a bacterial molecule that is involved in this process. They demonstrate that the protein grabs onto the sugar molecule with a Pac Man-like chewing motion and holds it until it can be used. Their results could help design therapeutics that could make the protein poorer at grabbing and holding and hence compromise the pathogen in the host. The study has now been published in “Biophysical Journal”.
The cells of the mouth, nose and intestinal mucosa produce large quantities of a chemical called sialic acid. Many bacteria possess a special transport system...
10.01.2017 | Event News
09.01.2017 | Event News
05.01.2017 | Event News
17.01.2017 | Earth Sciences
17.01.2017 | Materials Sciences
17.01.2017 | Architecture and Construction