Scientists are planting genetically engineered trees in dozens of research projects across the country, ignoring the pleas of environmentalists who fear dangerous, unintended consequences. When we’re talking about changing the very makeup of wild forests, we definitely need to apply caution,«said Kathleen Casey, with the Northwest office of the Sierra Club. Trees send their pollen huge distances, and the idea that this won’t contaminate the gene pool is ridiculous,«said Phil Bereano, a University of Washington professor of engineering.