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.
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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.

Turfgrass lawns help remove carbon dioxide from the atmosphere through photosynthesis and store it as organic carbon in soil, making them important “carbon sinks.” However, greenhouse gas emissions from fertilizer production, mowing, leaf blowing and other lawn management practices are similar to or greater than the amount of carbon stored by ornamental grass in parks, a UC Irvine study shows.
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These emissions include nitrous oxide released from soil after fertilization. Nitrous oxide is a greenhouse gas that’s 300 times more powerful than carbon dioxide, the Earth’s most problematic climate warmer.
“Lawns look great – they’re nice and green and healthy, and they’re photosynthesizing a lot of organic carbon. But the carbon-storing benefits of lawns can be counteracted by greenhouse gas emissions,” said Amy Townsend-Small, Earth system science postdoctoral researcher and lead author of the study, forthcoming in the journal Geophysical Research Letters.

The research results are important to greenhouse gas legislation being negotiated. “We need this kind of carbon accounting to help reduce global warming,” Townsend-Small said. “The current trend is to count the carbon sinks and forget about the greenhouse gas emissions, but it clearly isn’t enough.”

Turfgrass is increasingly widespread in urban areas and covers 1.9 percent of land in the continental U.S., making it the most common irrigated crop.

In the study, Townsend-Small and colleague Claudia Czimczik analyzed grass in four parks near Irvine, Calif. Each park contained two types of turf: ornamental lawns (picnic areas) that are largely undisturbed, and athletic fields (soccer and baseball) that are trampled and replanted and aerated frequently.

The researchers evaluated soil samples over time to ascertain carbon storage, or sequestration, and they determined nitrous oxide emissions by sampling air above the turf. Then they calculated carbon dioxide emissions resulting from fuel consumption, irrigation and fertilizer production using information about lawn upkeep from park officials and contractors.

The study showed that nitrous oxide emissions from lawns were comparable to those found in agricultural farms, which are among the largest emitters of nitrous oxide globally.

In ornamental lawns, nitrous oxide emissions from fertilization offset just 10 percent to 30 percent of carbon sequestration. But fossil fuel consumption for management, the researchers calculated, released almost as much or more carbon dioxide than the plots could take up, depending on management intensity. Athletic fields fared even worse, because – due to soil disruption by tilling and resodding – they didn’t trap nearly as much carbon as ornamental grass but required the same emissions-producing care.

“It’s unlikely for these lawns to act as net greenhouse gas sinks because too much energy is used to maintain them,” Townsend-Small concluded.

Previous studies have documented lawns storing carbon, but this research was the first to compare carbon sequestration to nitrous oxide and carbon dioxide emissions from lawn grooming practices.

The UCI study was supported by the Kearney Foundation of Soil Science and the U.S. Department of Agriculture.

About the University of California, Irvine: Founded in 1965, UCI is a top-ranked university dedicated to research, scholarship and community service. Led by Chancellor Michael Drake since 2005, UCI is among the most dynamic campuses in the University of California system, with nearly 28,000 undergraduate and graduate students, 1,100 faculty and 9,000 staff. Orange County’s largest employer, UCI contributes an annual economic impact of $3.9 billion.

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Wines and spirits are popular ingredients in many sweet and savory dishes. They add a flavorful dimension to entrees, sauces, and desserts. In our calorie conscious world, many cooks will often use a wine or spirit to add flavor to a dish in place of higher calorie fats such as butter or oil.

Because alcohol (ethanol) has a lower boiling point (78.5 degrees C) than water (100 degrees C) the presumption among many home cooks and culinary professionals has been that the alcohol cooks out when it is exposed to heat. But in 1992, a team of researchers at the University of Idaho, Washington State University, and the United States Department of Agriculture set out to confirm this assumption and found the assumption did not hold true.

In their study*, six recipes were prepared using various sources of alcohol including Burgundy wine, dry sherry, brandy, crème de cocoa, and Grand Marnier. A variety of preparations were used including applying no heat and refrigerating overnight, adding alcohol to a hot sauce, flaming, oven baking, and simmering (both 30 minutes and 2 ½ hours). Alcohol retention, after preparation, ranged from 4%-85% and was dependent upon a number of factors such as cooking temperature, size of the cooking vessel, cooking time, and the presence of other ingredients in the prepared dish. Breadcrumbs, for instance, which might absorb some of the alcohol and prevent it from evaporating.

Interestingly enough, the cherries jubilee recipe had one of the highest alcohol retentions at 77%-78% after the flames died out! The researchers explained this by saying that “with a flaming dish, alcohol loss is primarily the result of alcohol combustion. The alcohol continues to burn as long as minimum alcohol vapor pressure is maintained. Once this vapor is reduced below a certain point, the alcohol ceases to burn, which happens during flaming and thus accounts for the relatively high retention of alcohol during the process.”

After they reviewed their data, the research team concluded that “the assumption that all alcohol is evaporated when heat is applied during cooking is not valid.”

For home and professional cooks alike, this information is extremely important. There are many individuals who for age, health, religious, and/or personal reasons do not include alcoholic beverages in their diets and should not be served food prepared with alcohol. When cooking for these individuals, alcohol should never be used as an ingredient in the dishes served to them. Some of the alcohol will always remain in the prepared dish.

And, cautions Bonnie Taub-Dix, MA, RD, CDN, National Spokesperson for the American Dietetic Association and Director, BTD Nutrition Consultants, if the alcohol remains, so do the calories associated with it. She notes if you are substituting wine or spirits for fats or oils in your cooking in the hopes that the alcohol and the calories associated with them will both “all burn out and just leave the flavor behind”, that isn’t going to happen. You will still have to count some of the calories from the added wine or spirits.

My goal is to dispel this urban culinary myth and I need your help. Now that you know the facts, pass them on. And if you know any folks at the Food Network, please email them the link to this column!

*Jorg Augustin, PhD, Evelyn Augustin, MS, Rena L. Cutruffelli, Steven Hagen, PhD, and Charlene Teitzel. Alcohol Retention in Food Preparation, Journal of the American Dietetic Association, April 1992, Volume 92, Number 4.
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