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Imagine that you’re lost in a desert, or some other unfriendly environments.
You’ve got two choices. One is to stay in place and conserve supplies and water, in order to make themlast. The other is to push on stubbornly and hope that you find away out of your predicament. As it turns out, trees are like that too, when it comes to coping with the hotter, drier environment created by climate change. In a newarticle in the journal Global Change Biology, researchers fromUniversity of Washington studied two common tree species in southwestern Colorado, and found that each had developed a different survival strategy.
“We really wanted to identify the entire suite of strategies that a plant can use to growin drier environments, as well as which of these strategies each tree would employ,” UWbiology professor JannekeHilleRis Lambers, who co- authored the article with a graduate student Leander Anderegg, said in a press release.
In the summer of 2019, Professor JannekeHilleRisLambers studied the slopes of the La Plata Mountains in
Colorado’s San Juan National Forest, where a drought-ravaged ecosystemthat’s become I degree Fahrenheit hotter over the past 30years is putting stress on trees.
One of the species under pressure is the ponderosa pine, whose habitat is at the lower levels overlaps with that of the trembling aspen, a tree that lives most of further up the mountainside.
Researchers collected leaf, branch and tree ring samples of both trees. They studied that material to figure out how the trees adapted to drought conditions, and measured qualities such as the trees’ growth rate and the water tension inside their woody tissue.
The researchers found that the ponderosa pine used a strategy of ‘drought avoidance’ by conserving water, especially by shutting the tiny openings on its leaves to prevent water loss and slowing growth.
The trembling aspen, in contrast, simply tried to keep growing-at least for a while-during drought, with no change to water conservationstrategies. “Onthe endof their range, the trembling aspens are relatively short of these really fat leaves,”Janneke explained, “Internally, they also growreally strong vessels, which move water inside of the tree.
As a consequence, they are much denser and they also growslower. ”
They trembling aspen’s pushto growmight make it more vulnerable to severe or prolonged drought especially at its dry lower range. The ponderosa pine’s strategy is likely to gradually reduce its range.
Climate change is likely to shift the geographic range of many tree species, with species unable to tolerate heat moving northward or to higher heights.
38. What does the underlined word “predicament” mean?
A. Mind B.Desire C. Trouble D. Sympathy
39. How did ponderosa pines adapt to droughts?
A.By closing the openings on their leaves.
B.By growing slowly with fat leaves.
C.By moving water inside their trunk quickly.
D.By reducing the length of their water vessels.
40. What might be the suitable title for the passage?
A.What trees adapt to global warming better
B. Howtrees try to deal with climate change
C.Where trees go in rough climate change
D.Why trees stop growing in a hot environment
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