After one of his famous walks, the bearded naturalist John Muir wrote in 1896, "Few are altogether deaf to the preaching of pine trees."
But if today's trees could tell their stories, some American branches would be whispering new tales of origin: epics of genetic engineering in 150 groves from Puget Sound to the palmetto flats of South Carolina. Scientists are increasingly tweaking the genetics of trees in the laboratory to enable them to do such things as live at higher altitudes, produce more fruit, convert more easily into pulp for paper products, and grow faster for timber harvesting.
Moreover, advocates point to ways the new population could help the old. In some cases, harvest of the newfangled trees would save older ones from being cut down. And had the technology been available when the American chestnut blight broke out in the early 1900s, say some, it might have saved the US chestnut tree from near extinction.
To critics, however, these newest members of the sylvan society are Frankentrees - potentially toxic mutants and harbingers of an age when Muir's "lordly monarchs" might be superseded by megatrees from the lab. And as China and Brazil experiment with genetically engineered pine cones and apple blossoms, the debate in America is spreading beyond the laboratory, the Ivory Tower, and the confines of experimental groves.
"We're looking at a very dramatic impact on the ground here in the US, and especially the South," says Alyx Perry, director of the Southern Forests Network in Asheville, N.C. "There are inevitable risks that can irreversibly alter native systems."
Commercial use of "transgenic" crops began here in the South when the first genetically engineered tobacco plant was planted in 1986, barely a decade after American scientists figured out how to cut and paste DNA segments to create everything from spider silk to glow-in-the-dark guppies.
Now, as the tinkerers take on the forests, the big question is less how to do it than whether it should be done. The South - America's fastest-growing pulp producer - is the most likely region for commercial use of the experimental trees. The US Department of Agriculture has received more than 100 applications for use of the trees. And even as some heavy paper users, such as Kinko's, pledge not to use their products, the technology is taking root:
• The UN has approved use of genetically engineered trees that take in more carbon than normal trees, and so help to offset industrial emissions.
• Hawaiian officials have approved pest-resistant papaya trees in response to infestations that nearly wiped out native populations. The new class of trees has already provided a critical economic boost.
• The Department of Defense has ordered research into arboreal warning systems - for instance, trees with foliage designed to change color in reaction to a biochemical attack.
Blowing in the wind
Unlike altered crops such as soybean and wheat, genetically engineered trees are surrounded by their wild cousins.
One worry is that the seeds of the experimental trees will take root amid wild populations, changing the aesthetics of the woods. But scientists caution that doesn't mean a slow incursion of the new breed: Trees, the ultimate survivalists, will express only those genes that are necessary for their longevity. "When they escape, the [new genetic material] may act differently or it may not express at all," says Jim Hemrick, a tree-genetics expert at the University of Georgia in Athens.
That's small comfort to critics, who say industry representatives seem more concerned with addressing public-relations issues - key to approval of the technology for commercial use - than confronting the ethical side of tampering with the lungs of the world. Many were outraged when scientists began keeping the locations of their experimental groves secret, in response to activists' attacks on genetically engineered plots in Oregon a few years ago.
Conservation and recycling of paper products, these environmentalists say, are the safest routes to protecting forests.
"Regardless of all the problems with agri-crops, [tree geneticists are] saying, let's do this with trees, which live for hundreds of years. What are they thinking?" asks Anne Petermann, codirector of the Global Justice Ecology Project in Hinesburg, Vt.
Aside from the potential environmental impact, the trees could also have an impact on commercial uses of the wood.
If some of the softer trees, bred for pulp production, were to show up on timber lands, for instance, saw mills could cut them unwittingly for use as lumber, then find out they're too soft to be turned into usable boards.
But perhaps a more essential question is this: Who owns the trees, and who can claim the products of engineered seeds that drift into the wild? As companies produce the trees and use their products, they want to make sure that drifting seeds don't get used by other interests. Already, more than 100 "gene drift" lawsuits have been brought over various farm crops by companies such as Monsanto, and a similar phenomenon is expected with engineered trees.
"This brings up the issue of intellectual property rights of life forms, and that gets into a whole other can of worms," says Brad Hash, a board member at the Native Forest Network in Missoula, Mont. "You could have loggers and private landowners who would not have ownership to the organisms on their own property."
To opponents of the engineered trees, it's not just the world's forests, but the marvel and culture surrounding them, that hang in the balance - and many on both sides are recommending caution.
"It's good to be conservative," says Mr. Hemrick at the University of Georgia. "It's good to have people reminding us that a worst-case scenario could happen. But it's fairly unrealistic that we'll get a disaster."