Tropes

impactlab_2010 00629.txt

#Croplands Are Chipping Away at Carbon Stocks? This is all you will find if you live in NE Voice of experience Natures capacity to store carbon, the element at the heart of global climate woes, is steadily eroding as the worlds farmers expand croplands at the expense of native ecosystem such as forests. The tradeoff between agricultural production and maintaining natures carbon reservoirs native trees, plants and their carbon-rich detritus in the soil is becoming more pronounced as more and more of the worlds natural ecosystems succumb to the plow. The problem, experts say, is most acute in the tropics, where expanding agriculture often comes at the expense of the tropical forests that act as massive carbon sinks because of their rich diversity and abundance of plant life. The seriousness of the problem is documented in the most comprehensive and fine-grained analysis of the worlds existing carbon stocks and global crop yields. The study is published online this in the Proceedings of the National Academy of Sciences (PNAS) by a team of researchers from the University of Wisconsin-Madison, the University of Minnesota, Stanford university, Arizona State university and The Nature Conservancy. The article is part of a special PNAS feature on climate mitigation and agricultural productivity in the tropics. oewe analyzed the tradeoffs between carbon storage and crop production at a level of detail that has never been possible before, according to Stephen Carpenter, one of the senior authors of the study and a professor at the Center for Limnology at UW-Madison. oethe main news is that agricultural production by clearing land in the tropics releases a lot of greenhouse gases per unit of food produced. Compared to the worlds temperate regions, the tropics release nearly twice as much carbon to the atmosphere for each unit of land cleared, explains Paul C. West, a UW-Madison graduate student and the lead author of the new study. oetropical forests store a tremendous amount of carbon, and when a forest is cleared, not only do you lose more carbon, but crop yields are not nearly as high as they are in temperate areas. oethis creates a kind of double whammy for a lot of tropical agriculture: we have to clear carbon-rich ecosystems to create tropical croplands, and unfortunately they often have lower yields than temperate systems, says Jonathan Foley, director of the University of Minnesotas Institute on the Environment and a co-author on the study. oein terms of balancing the needs of food production and slowing carbon dioxide emissions, this is a tough tradeoff. In the tropics, for example, it is estimated that for every ton of crop yield, carbon stocks are diminished by as much as 75 tons. Such attrition, say West and his colleagues, makes a strong case for intensifying agriculture on already-converted land instead of putting new fields into production. oeone path is to expand agricultural land, says West. oethe other path is to intensify agriculture on existing lands. The realty is there will be some of both. Today, about 20 percent of the land in temperate regions is in cropland. In the tropics, 11 percent of the land is farmed. However, in the tropics pressure to plant more land is growing fastest due to increasing human population, changing diets, food security concerns, and a rising demand for the raw materials of biofuels. mroevia sciencedaily. com Share Thissubscribedel. icio. usfacebookredditstumbleupontechnorati t

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