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The Poplar of the Future
Brandon Keim, 23 Sep 06

445528_end_of_summer_3.jpg The poplar tree recently became just the third plant species -- and the first woody plant -- to have its genome mapped.

Poplars are founded in temperate regions throughout the world, including the northwest and eastern regions of the United States. They grow extremely fast, and in the last thirty years have been bred and managed by timber companies and forestry scientists.

Heavy hybridization, with trees bred for increased yields, faster growing cycles, and resistance to disease and pests has fueled a commercial boom. More than 2300 square miles of poplar is grown in the United States. Poplar is used in paper, pulp, particle board and firewood; it's found in matches, fruit boxes and chopsticks. Its root structure makes it useful for filtering chemical wastes, fixing soil and stopping erosion. China is using it to halt the advance of the Gobi Desert. The U.S. government has made it a centerpiece of its biofuels efforts, and it could conceivably be planted on thousands of square miles of unused farmland.

In short, anything that affects how poplar is farmed could profoundly impact both people and the environment. And there's no question that the poplar's mapping will produce major changes in breeding and management.

"We now have insights into the numbers and types of genes. We can ask questions. When are they turned on, when are they turned off? How do they respond to nutrient stress, drought stress, insect attack? We can formulate studies to overcome these stress causing factors," said Gerald Tuskan, who led dozens of scientists from North America and Europe in mapping the genome.

Many of the changes will undoubtedly involve genetic modifications. What forms will all this take? Will it be done sustainably? There is potential for both good and bad.

As it stands, the timber industry isn't generally associated with progress. Companies rely heavily on fertilizers and pesticides -- though less, it should be noted, than with corn and soy. They are grown in vast monocultures, producing what E.O. Wilson, in a Mother Jones article, described so:

. . . [Wilson] estimates that a pine plantation contains 90 to 95 percent fewer species than the forest that preceded it. He compares the effects of tree farms on biological diversity to "building a line of Wal-Marts.

The timber industry has sought genetic modifications in line with what has been done to ill or unsuccessful effect in feed crops, including engineering for pesticide and herbicide resistance. This increases pesticide and herbicide use -- never a good thing. There are, however, other interesting possibilities for poplar modification.

"The opportunities are where we would use the trees either for energy or wood products. If the concern is combatting global warming, the most promising alternatives are where wood can displace fossil fuels or energy-intensive materials," says Gregg Marland, a scientist in the Oak Ridge National Laboratory's Carbon-Climate Simulation Science Group.

Poplar appears to have great potential as a biofuel, providing fiber easily converted into ethanol. The U.S. Departments of Energy and Agriculture have proposed to replace a third of fossil fuel used in transportation with biofuels by 2030 (check the report, creepily entitled "Billion Ton Vision.") Properly modified to grow faster and bigger, break down easier, and survive in stressful conditions, poplar is seen as a potentially vast source of cellulose -- one that could even replace corn and soy, both of which are far more environmentally exhausting, as a primary source of ethanol. Moreover, the trees could absorb a great deal of carbon dioxide. Much of it would be released when processed, but some would remain safely in the ground.

If you look at modern agriculture, and compare it to intensive forestry, the amount of chemical use is an order of magnitude less in forest stettings," said Tuskan. Replacing corn and soybeans with poplar, he said, will result in "less soil erosion, less chemical use, and higher accumulations of carbon in the soil of that converted agricultural land.

As has been noted in Worldchanging, biofuels won't solve all our fossil fuel problems. If GM poplar develops like other industrial biotech plants, such as corn and cotton, it could do some damage, either by increasing chemical use or releasing debilitating strains into the wild. But anything that replaces fossil fuels, fixes CO2 and can be swapped for row crops has a lot going for it. Moreover, poplars, like many other plants, could be engineered to handle drought, salinity and a changing climate. Done sustainably, the techniques born of the mapping of the poplar genome could be a boon. And because the poplar's genome is now public, and the tree found in much of the world, it's certain that much research will done outside the confines of industrial biotechnology. The poplar's seeds of knowledge are now cast wide.

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Poplar is a very fast growing tree. It is turned into oriented strandboard at an amazing rate. A politically motivated shutdown of a huge Alberta plant has since caused the price to double. (the softwood lumber dispute...remember?)It is now no longer competitive with plywood. Plywood, which is much more eco-unfriendly, is being used instead to fuel the great housing booms "out west".
Eventually large US firms will build big plants in Canada to harvest the poplar and turn it into "chipboard". Until then, they are growing nicely, taking CO2 out of the air and turning it into wood. The pine forests are being cut down and re-planted at a furious rate throughout Ontario and New Brunswick, and so thousands of tons of sawdust and lumber are being taken out of the world's CO2 pool every day.
Smarter people than me will be able to figure out why that is important. But it is what is happening. I think in balance that this could be good news. What do you think?

Posted by: Bill Fedun on 26 Sep 06

That's real interesting. The scientists that I talked to said, unanimously, that GM poplar was a good enough idea, and poplar as carbon sequester plenty sensible, so long as companies don't cut down existing forests to plant it. Business and academic realities being, sadly, not the same.

I also feel that I underestimated a little of what poorly designed poplar could look like; I reasoned that, for example, lignin-deficient strains too weak to support themselves would be unable to survive in the wild, and therefore not threaten existing forests. But as Brian Tokar pointed out in a later email, some GM organisms can be deficient but still reproduce -- GM salmon, for instance, which have diluted and weakened wild stocks. This is a good point, and I wish I had more confidence that the EPA was monitoring things closely. With any luck they learned their lesson from the various biopharming debacles.

Posted by: Brandon Keim on 8 Oct 06



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