The biotechnology firm ArborGen has asked the USDA for permission to conduct 29 field trials of genetically engineered "cold tolerant" eucalyptus trees in the U.S. For the first time in history, this massive experiment, which is on the verge of being green-lighted, will literally be using nature as the laboratory to test more than 260,000 genetically engineered trees. Scientists across the U.S. are voicing concerns over this proposal.