VOA科学技术2024--Forest Service Moving Trees to Save Them

Some important tree species native to the northwestern states in the U.S. are no longer growing well because of climate change.

As conditions change in states such as Washington, Oregon and California, trees such as the Douglas fir, Western red cedar¹, giant sequoia² and redwood may need to move -- with the help of humans.

Some of the trees do not do well when temperatures rise. Others suffer during times of drought. The goal is to move the trees to areas where the climate might more suitable.

Forest scientists are generally in favor of moving the trees so they do not die out. However, not all of the scientists agree on the best way to do it.

There are three ways to move trees: assisted population migration³, assisted species migration and range expansion.

Assisted population migration involves scientists moving a tree's seeds within its current growing range. Assisted species migration involves scientists moving a species far from its existing area. In this case, that would include moving redwoods and sequoias from California to Washington.

The third way, range expansion, moves trees just outside their current growing range. Each way has different results for the trees and other animals and insects that depend on the trees.

Michael Case is a forest ecologist at the Nature Conservancy in Virginia. He said "there is a huge difference" among the different migration methods.

He said the risk of failure increases "whenever you plant something in an area where it is not locally found." He said the risk is not only to the trees. There is also the risk of causing problems in the ecosystem⁴.

Case is working on an assisted population migration program with Douglas fir and Western hemlock⁵ trees. He is testing whether the trees, originally from drier parts of the northwest, can do well in western Washington where there is a drought. His organization believes that assisted population migration has fewer risks.

The U.S. Forest Service also takes part in assisted population migration programs. Dr. David Lytle is the agency's deputy chief for research and development. He said the agency is "very very cautious" about moving plants outside of their "historic range."

Douglas Tallamy is a professor of entomology and wildlife ecology at the University of Delaware. He said one worry about species migration is that local caterpillars⁶ might not eat the leaves of trees that are new to the area. The caterpillars serve as food for birds and other animals, so they must have a good food source.

Although the concerns are documented, the city of Portland, Oregon, is working on a species migration project for 11 tree species. The project includes three oak trees: California black oak, canyon⁷ live oak and interior live oak. Tallamy said oak trees are among the most important in North America. "When you move them out of range," he said, "the things that are adapted to eating them no longer have access to them."

The city responded to questions from the Associated Press, and said it is using guidelines "from universities, state and federal sources" and more, in its project.

Another group working on species migration projects in the northwest is called PropagationNation. To propagate means to produce a new plant through the use of seeds or parts of another plant.

That organization is planting non-local trees around the Seattle, Washington area in hopes that they will start growing in places where Western red cedar, Western hemlock and big leaf maple⁸ are having trouble.

David Milarch is the leader of a group in Michigan that supports keeping old trees alive. It is called Archangel Ancient Tree Archive. Milarch said the hope is to permit redwoods and sequoias to grow in areas to the north. The hope is not to replace native trees.

He said his group hopes the trees "will still be here in 100 to 200 years and not join the list of trees that are going extinct."

The organizations that are not practicing widely accepted methods for moving species feel like the risks are worth it.

But Robert Slesak is not sure about either practice. He oversees⁹ population migration sites run by the U.S. Forest Service in California, Oregon and Washington.

He said he has concerns about assisted species migrations¹⁰ and assisted population migrations that lack experimental rigor¹¹. Rigor describes an activity that has been tested with high standards.

He said all of the ideas about how to move trees should follow experiments that have already produced strong results.

"Everyone knows we need to do some kind of action related to climate, but there's a real risk of making it worse."

Words in This Story

drought –n. a dry weather period

suitable –adj. comfortable or correct

migration –n. the movement of something to a new place

range –n. the usual area of land covered by a plant or tree (in this case)

ecologist –n. a person who studies living things and their environment

locally –adj. a small area where something is originally found

cautious –adj. careful or concerned

adapted –adj. something that has changed and now functions in a new place

respond –v. to answer

replace –v. to put something new in place of something

to go extinct –v. to die out

rigor –n. the quality of being exact, careful or strict

1 cedar   

n.雪松，香柏(木)

参考例句：

• The cedar was about five feet high and very shapely.那棵雪松约有五尺高,风姿优美。
• She struck the snow from the branches of an old cedar with gray lichen.她把长有灰色地衣的老雪松树枝上的雪打了下来。

2 sequoia   

n.红杉

参考例句：

• The sequoia national forest is at the southern end of the sierra nevada range.红杉国家公园位于内华达山脉南端尽头处。
• The photo shows the enormous general Sherman tree in California's sequoia national park.照片显示的是加利福尼亚州红杉国家公园内巨大的谢尔曼将军树。

3 migration   

n.迁移，移居，（鸟类等的）迁徙

参考例句：

• Swallows begin their migration south in autumn.燕子在秋季开始向南方迁移。
• He described the vernal migration of birds in detail.他详细地描述了鸟的春季移居。

4 ecosystem   

n.生态系统

参考例句：

• This destroyed the ecosystem of the island.这样破坏了岛上的生态系统。
• We all have an interest in maintaining the integrity of the ecosystem.维持生态系统的完整是我们共同的利益。

5 hemlock   

n.毒胡萝卜，铁杉

参考例句：

• He was condemned to drink a cup of hemlock.判处他喝一杯毒汁。
• Here is a beech by the side of a hemlock,with three pines at hand.这儿有株山毛榉和一株铁杉长在一起，旁边还有三株松树。

6 caterpillars   

n.毛虫( caterpillar的名词复数 )；履带

参考例句：

• Caterpillars eat the young leaves of this plant. 毛毛虫吃这种植物的嫩叶。
• Caterpillars change into butterflies or moths. 毛虫能变成蝴蝶或蛾子。 来自辞典例句

7 canyon   

n.峡谷，溪谷

参考例句：

• The Grand Canyon in the USA is 1900 metres deep.美国的大峡谷1900米深。
• The canyon is famous for producing echoes.这个峡谷以回声而闻名。

8 maple   

n.槭树，枫树，槭木

参考例句：

• Maple sugar is made from the sap of maple trees.枫糖是由枫树的树液制成的。
• The maple leaves are tinge with autumn red.枫叶染上了秋天的红色。

9 oversees   

v.监督，监视( oversee的第三人称单数 )

参考例句：

• She oversees both the research and the manufacturing departments. 她既监督研究部门又监督生产部门。 来自《简明英汉词典》
• The Department of Education oversees the federal programs dealing with education. 教育部监管处理教育的联邦程序。 来自互联网

10 migrations   

n.迁移，移居( migration的名词复数 )

参考例句：

• It foundered during the turmoils accompanying the Great Migrations. 它在随着民族大迁徙而出现的混乱中崩溃。 来自辞典例句
• Birds also have built-in timepieces which send them off on fall and spring migrations. 鸟类也有天生的时间感应器指导它们秋春迁移。 来自互联网

11 rigor   

n.严酷，严格，严厉

参考例句：

• Their analysis lacks rigor.他们的分析缺乏严谨性。||The crime will be treated with the full rigor of the law.这一罪行会严格依法审理。