It’s a sound you will probably never hear, a sickened tree sending out a distress signal. But a group of scientists has heard the cries, and they think some insects also hear the trees and are drawn to them like vulture to a dying animal. Researchers with the US Department of Agriculture’s Forest Service fastened sensors to the bark of drought-stricken trees clearly heard distress calls. According to one of the scientists, most parched trees transmit their plight in the 50-hertz to 50-kilohertz range. (The unaided human ear can detect no more than 20 kilohertz). Red oak, maple, white pine, and birch all make slightly different sounds in the form of vibrations at the surface of the wood.

The scientists think that the vibrations are created when the water columns inside tubes that run along the length of the tree break, a result of too little water following through them. These fractured columns send out distinctive vibration pattems. Because some insects communicate at ultrasonic frequencies, they may pick up the trees' vibration and attack the weakened trees. Researchers are now running tests with potted trees that have been deprived of water to see if the sound is what attracts the insects. “Water-stressed trees also smell differently from other trees, and they experience thermal changes, so insects could be responding to something other than sound”, one scientist said.

It can be inferred from the passage that research concerning the distress signals of trees ...............

Câu hỏi liên quan

• What type of band is NOT mentioned in the article?

• The author mentions the “ shoesbox under the bed” in order to ................

• It can be inferred from the passage that social workers, employers, and politicians concern themselves with the study of learning because they need to ______.

ZUNIA12

• Horace Pippin discovered he could paint and draw .............

• What is the passage primarily about?

• The word “imprisonment” in paragraph 2 is closet in meaning to _________.

• What can the word adorning be best replaced by?

•  The word “exert” in bold in paragraph 1 is closest in meaning to ................

• The highlight word “it” in the passage refers to ................

• What is the main idea of this passage?

• The word “forces” in line 9 could best be replaced by:

• Which of the following is NOT supported by the passage?

• It can be inferred from the passage that the courtship of great horned owls ................

• The word “lies” in the first paragraph could be best be replaced by ______.

• The word “assessing” in paragraph 2 could best be replaced by ...........

• What is the main point the writer is trying to make in the last paragraph?

• The final product of the process of drying liquids that uses the first method will be ______.

• The author implies which of the following is true?

• According to the passage, why did colonial printers avoid major publishing projects?

• According to the passage, all of the following are true EXCEPT ................