Shade trees can protect coffee crops

Sustainable farming that employs shade trees may improve crops' resistance to temperature and precipitation extremes that climate changes are expected to trigger, according to an article published in the October issue of BioScience. The article, by Brenda B. Lin, Ivette Perfecto, and John Vandermeer, of the University of Michigan, focuses on coffee production, although their conclusions could be applicable to other economically important crops, including cocoa and tea, which also were traditionally grown under shade trees. The scientists marshal evidence that the intensification of coffee production in recent decades has made that crop--and the millions of people whose livelihood depends on it--more vulnerable to higher temperatures and changes in precipitation. In an effort to boost production, growers have increased their use of pesticides and relied less on shade trees, but the evidence suggests that these trends make the crop more susceptible to weather events. The benefits of shade trees appear greater in more marginal growing areas. Lin and her colleagues urge further efforts to determine where a return to more traditional agroforestry techniques is likely to protect the livelihoods of farmers threatened by climate change.

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