Ateamledbyanurseryman(花圃工人)andhissonshasracedagainsttim...

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A team led by a nurseryman (花圃工人) and his sons has raced against time for 20 years, using branches from some of the world’s biggest and most long-lasting trees to produce clones that could restore ancient forests and help fight climate change.

Now comes the most ambitious step of the project: getting the new trees into the ground. Plantings of two dozen clones from California’s huge coastal redwoods will take place Monday in seven nations: Australia, New Zealand, Great Britain, Ireland, Canada, Germany and the U.S.

The lab-produced trees are genetic copies of three huge trees that were cut down in northern California more than a century ago. Remarkably, new branches still grow from the stumps (树桩), including one known as the Fieldbrook Stump, which measures 35 feet in diameter (直径). It’s believed to be about 4,000 years old.

“We need to reforest the planet. To do that, it just makes sense to use the largest, oldest trees that ever lived,” said David Milarch, co-founder of the non-profit Archangel Ancient Tree Archive.

Milarch and his sons Jared and Jake, who have a family-owned nursery, became concerned about the condition of the world’s forests in the 1990s. They began traveling across the U.S. in search of “champion” trees that have lived hundreds or even thousands of years, believing that better genes make it possible for them to outlive others of their species. Scientific opinion varies on whether that’s true, with skeptics saying the survivors may simply have been lucky.

The Archangel team says they’ve developed several methods of producing genetic copies. They focus on towering sequoias （高耸的水杉）and redwoods, considering them best suited to absorb great amounts of carbon dioxide (CO2), the greenhouse gas primarily responsible for climate change.

The challenge is to find places to put the trees, people to look after them and money to continue the project, Jared Milarch said. The group is funded through donations and doesn’t charge for its clones.

“A lot of trees will be planted by a lot of groups on Arbor Day, but 90 percent of them will die,” David Milarch said. “You can’t plant trees and walk away and expect them to take care of themselves.” Those receiving Archangel redwoods have promised to care for them properly.

28. According to the text, the clones _____.

A. are rather expensive B. are based on dead ancient trees

C. have been experimented for 20 years D. have been widely grown across the U.S.

29. To reforest the planet, David Milarch chooses the largest, oldest trees because ___.

A. they are lucky trees B. they have better genes

C. they are easier to plant D. they look more beautiful

30. David Milarch’s team believes that genetic copies from sequoias and redwoods __.

A. can take in more greenhouse gases B. are hard to survive for a long time

C. are likely to cause climate change D. may be a threat to existing plants

31. What is stressed by David Milarch in the last paragraph?

A. The need of financial support. B. The difficulty of finding places.

C. The importance of caring for trees. D. The challenge of running his group.