BIG BENEFIT from bigger trees WHEN IT COMES TO TREES, bigger
is better. Big trees generate more seeds, provide more habitat for animals, and help forests resist disturbances. Big trees also occur in unique patterns and store more carbon compared to small trees. Big trees three or more feet in diameter accounted for nearly half the biomass measured at a Yosemite National Park site, yet represented only 1 percent of the trees growing there. Professor James Lutz, UW research scientist in environmental and forest sciences, is the lead author of the largest quantitative study yet on the importance of big trees in temperate forests. Lutz and his colleagues, along
with help from students and citizen volunteers, are studying the new 63-acre study site in the western part of Yosemite National Park. A study in 2009 that involved Lutz found that the density of large-diameter trees in Yosemite declined nearly 25 percent between the 1930s and the 1990s. “There are less large trees than there used to be,” says Lutz. “And tree mortality rates for trees bigger than 18 inches are higher than in previous decades.” Scientists don’t know precisely how forests are changing, but because they will return every year to Yosemite they should gain valuable knowledge about why trees are dying and how the forest works.
USDA REPORT full of baloney IF YOU FILL YOUR SHOPPING CART with healthy foods, it will cost you less than if you purchased highly processed “junk” food full of high fat and sugar content, according to a report recently released by the research arm of the U.S. Department of Agriculture. Not so, says Adam Drewnowski, professor of epidemiology in the UW School of Public Health and director of the UW’s Nutritional Science program. While USDA economists told USA Today that “the price of potato chips is nearly twice as expensive as the price of carrots by portion size,” Drewnowski says the government agency is misrepresenting the stats. The USDA, he says, is measuring food costs per gram as opposed to per calorie, thus making vegetables appear cheaper. One hundred grams of carrots may be cheaper than 100 grams of chocolate, but the carrots provide 40 calories as opposed to the 600 calories the same weight in chocolate provide. Drewnowski’s latest research found that diets containing specific nutrients associated with lower risk of chronic disease cost more than diets with less of these nutrients. This cost variable may be one reason why lower income groups don’t comply with dietary guidelines and have the highest rates of diet-related chronic disease. For more information about healthy diets and Adam Drewnowski’s work, go to www.bit.ly/KcJQOT
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