Trees are able to defend themselves against diseases. They have both protective structures and protective processes. Thanks in large part to research done by Dr. Alex Shigo, we now know a great deal more about the way trees protect themselves than we did 50 years ago.
Just as our skin keeps harmful bacteria on the outside, bark (树皮) keeps out tree diseases. Since they can’t move around to avoid dangers, trees need thicker “skin” than we do. Living and non-living tissues protect tree trunks, roots, and branches from mechanical injury, drying out, and diseases.
But when something destroys this first line of defense — tears through the bark — what happens internally is interesting. When an injury occurs, a tree will transform some of its stored sugars to make masses of defensive chemicals, which are then distributed in a specific pattern internally around the wound. Dr. Shigo was the first to document this pattern, which he called CODIT — Compartmentalization (分室化) of Decay (腐烂) in Trees.
In making these CODIT compartments, trees form chemical walls to protect themselves from infection. The success of this walling-off process depends a lot on the species. Hard maple, for instance, can generate a strong CODIT response while species like soft maple achieve only an average level. Some, on the other hand, barely manage to form any chemical walls.
Overall tree vitality is another important factor. Even a hard maple may not be able to form strong chemical walls if it’s in a weak state. By definition, landscape trees are stressed as compared to their forest-living cousins. A street tree is worse off, faced with limited root space, air pollution, and more. The size of the injury also makes a difference. Even a healthy tree can have its defenses destroyed by a large wound.
Humans can help maximize trees’ defense capability by watering during dry seasons, keeping things out of the root zone, etc. In return, trees will help keep us in good health by offering shade, beauty, and companionship.
1. What will happen first if diseases come close to trees?A.Infection will occur internally. | B.Bark will provide protection |
C.Chemical walls will take effect. | D.Defense chemicals will be formed. |
A.Groundbreaking. | B.Conservative. | C.Ambiguous. | D.Straightforward. |
A.Trees can form chemical walls |
B.The size of the injury affects CODIT. |
C.Trees cannot protect themselves if weakened. |
D.The effectiveness of CODIT varies among species. |
A.The gift of the trees. | B.The magic of CODIT. |
C.The function of the bark. | D.The self-preservation of the trees. |
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【推荐1】Great Theatres in the World
The Palais Garnier
Paris
The Palais Garnier is the best known theater of Paris. In 1669 Louis XIV gave a green light to the opera theater foundation in honor of the poet Pierre Perren and the composer Robert Kamber. Throughout centuries the theater changed its name and location several times up to the moment it appeared in Paris district in the nineteenth century.
Palace of Catalan Music
Barcelona
The Palace of Catalan Music in Barcelona is a quite young opera house founded in 1891. The facade (外观) of the Palace reminds that in Spain it is the place where the European and Arabian cultures connected closely.
But the main feature of the concert hall is its lighting. The illumination (照明) is completely natural. The Palace of Catalan Music’s roof is made of color glass fully. Lights of the sun create an indescribable effect!
Vienna State Opera
Vienna
Vienna State Opera was built in 1869. Its opening was marked by Mozart’s opera Don Juan. On the other hand, the building often became the object of severe criticism since it was built in extremely widespread neo-renaissance style.
La Scala Opera House
Milan
In 1776, the Milan architect Giuseppe Piermarini liked the piece of earth on the site of the destroyed Church of Santa Maria Della Scala. He decided to construct the opera theater on this place, which inherited (继承) the name of its ancestor building. The Europa Riconosciuta by the composer Antonio Salieri became the first opera of the La Scala theater.
1. Which theatre has the longest history?A.The Palais Garnier. | B.Palace of Catalan Music. |
C.Vienna State Opera. | D.La Scala Opera House. |
A.Its location. | B.Its adoption of natural light. |
C.Its historical background. | D.The styles of different periods. |
A.They both received criticism. |
B.They were both totally destroyed. |
C.They were both constructed on the site of a church. |
D.Their openings are both marked by shows of masterpieces. |
The world is facing as astonishing rise in the number of old people, and they will live longer than ever before. Over the next 20 years the global population of those aged 65 or more will almost double, from 600 million to 1.1 billion. The experience of the 20th century, when greater longevity translated into more years in retirement rather than more years at work, has persuaded many observers that this shift will lead to slower economic growth, while the swelling ranks of pensioners will create government budget problems.
But the notion of a sharp division between the working young and the idle old misses a new trend, the growing gap between the skilled and the unskilled. Employment rates are falling among younger unskilled people, whereas older skilled folk are working longer. The divide is most extreme in America, where well-educated baby-boomers (二战后生育高峰期出生的美国人) are putting off retirement while many less-skilled younger people have dropped out of the workforce.
That even the better-off must work longer to have a comfortable retirement. But the changing nature of work also plays a big role. Pay has risen sharply for the highly educated, and those people continue to reap rich rewards into old age because these days the educated elderly are more productive than the preceding generation. Technological change may well reinforce that shift: the skills that complement computers, from management knowhow to creativity. Do not necessarily decline with age.
1. what is happening in the workforce in rich countries?
A.younger people are replacing the elderly |
B.well-educated people tend to work longer |
C.unemployment rates are rising year after year |
D.people with no college degree do not easily find work |
A.Longer life expectancies |
B.Profound changes in the workforce |
C.rapid technological advance. |
D.A growing number of well-graduated. |
A.Economic growth will slow down. |
B.Government budgets will increase. |
C.More people will try to pursue higher education |
D.There will be more competition in the job market. |
A.Unskilled workers may choose to retire early. |
B.more people have to receive in-service training. |
C.Even wealthy people must work longer to live comfortably in retirement. |
D.People may be able to enjoy generous defined-benefits from pension plans. |
A.Computers will do more complicated work. |
B.More will be taken by the educated young. |
C.Most jobs to be done will be creative ones. |
D.Skills are highly valued regardless of age. |
【推荐3】The cognitive health and development of boys may be affected by their mothers’ body mass index (BMI) (体重指数) while pregnant with them, according to research from Columbia University and the University of Texas at Austin.
The study, which was published in the journal BMC Pediatrics on Friday, observed 368 subjects from low-income African American and Dominican women during the second half of their pregnancies, and then evaluated their children three and seven years later. Researchers found that the sons of women whose BMIs indicated that they were overweight or obese when they became pregnant were more likely to show less developed athletic skills as 3-year-olds and lower intelligence as 7-year-olds compared to boys whose mothers were at “normal” weights during pregnancy.
Among boys, the study found, mothers’ overweight and obesity connected with IQ scores between 4.6 and almost 9 points lower than those of boys whose mothers’ weights were in the “normal” range before pregnancy. Researchers did not observe the same phenomenon among daughters whose mothers had been obese.
“These findings aren’t meant to shame or scare anyone,” Elizabeth Widen, assistant professor of nutritional sciences at UT Austin and one of the study’s co-authors, said in a press release. “We are just beginning to understand some of these interactions between mothers’ weight and the health of their babies.”
Why mothers’ obesity appeared to affect childhood IQ was unclear, but earlier research has suggested that there is a relationship between a mother’s diet and her child’s later IQ, according to Columbia University. Researchers did not control for what the mothers ate, the press release noted.
The study’s authors wrote that because childhood IQ has been shown to be an indicator of later success in life, studying how a mother’s obesity could affect the IQ of her child is worthwhile.
1. How did researchers carry out the study?A.By measuring mothers’ body mass index. |
B.By watching mothers and babies for years. |
C.By comparing 3-year-old babies with 7-year-olds. |
D.By evaluating the health of mothers and their babies. |
A.To show links between mothers’ weight and babies’ IQ. |
B.To make those overweight mothers shameful and scared. |
C.To warn some fat mothers to keep a balanced diet. |
D.To persuade more obese mothers to lose weight. |
A.Doubtful. | B.Worrying. |
C.Significant. | D.Interesting. |
A.Entertainment. | B.Novel. |
C.Education. | D.Health. |
【推荐1】Bred to be more sweeter, today’s cherries, bananas and apples taste different than they used — to but not necessarily better. Among fruit farmers, the word “quality” is now routinely used as a standard for “high in sugar”, though firmness, color and size are also considerations. In a recent study about ways to enhance the sweetness of fruit using “molecular (分子的) approaches”, a group of plant scientists wrote that, in general, the sugar content of many fruits are now higher than before owing to continuous selection and breeding. Modern apple varieties, the scientists stressed, were on average sweeter than older ones.
The sweetness of fruit depends not just on how it is bred but also on growing conditions, yield and harvest. The lead researcher, Sugiura, said, “If you could taste an apple harvested 30 years ago, you would feel the difference.” He believed that modern apples are picked so early that even if they are bred for sweetness, they often don’t develop their full character. The fragrance (香味) never develops in fruit that is harvested too early.
Jim Cooper, an apple farmer in England, is regretful to admit the fact that many people will never taste the “strawberry hint” in a really ripe Pearmain, a type of heritage apple. In a way, the rise of consistently sweeter fruit in our lifetimes has been a victory of plant breeding. After all, it’s a rare person who would seek out bitter grapes if they could have sweet ones instead.
But the sweetness of modern fruit is not without its problems, especially for people with diabetes (糖尿病), who have to reduce their intake of higher-sugar fruits. Fruit that is bred sweeter also tends to be lower in the chemicals that make it healthy. Considering health, maybe the real problem with modern fruit is that it has become yet another sweet thing in a world with sugar. Even grapefruits, which used to be quite bitter, are sometimes now as sweet as oranges. If you’ve never tasted a sour cherry, how can you fully appreciate a sweet one?
1. In what aspect is many fruits different from before?A.Sugar content. | B.Soft skin. | C.Bright color. | D.High yield. |
A.They are bred too early. | B.They taste so sweet. |
C.They are losing a good flavor. | D.They need a higher yield. |
A.Favorable. | B.Critical. | C.Ambiguous. | D.Indifferent. |
A.It’s a wise choice to breed fruits for sweetness. |
B.Breeding sweet fruits improves the quality of fruits. |
C.Some fruits like grapes and cherries taste the same. |
D.The sweetness of fruits will cause health issues. |
【推荐2】“A beautiful field of flowers can be a rather noisy place. It’s just that we can’t hear the sounds.” Scientists at Tel Aviv University have conducted a six-year experiment, proving that plants make noise in certain stressful situations.
Plants produce a high frequency (频率) clicking sound, and when short of water, or damaged, the clicks become far more regular. They also made different sounds, depending on whether they were thirsty or injured. “Each plant and each type of stress is related to a specific sound,” said Professor Lilach Hadany, who led the research study.
Focusing particularly on tomatoes, wheat and corn, the plants were placed in a soundproof(隔音的)room and recorded by microphones. Some plants were starved of water, others cut, and a control group was left undamaged. The researchers used an algorithm (算法) to separate the noises, suecessfully telling the difference between the sounds depending on whether they were dry or cut. The algorithm did this in a greenhouse setting which included far more surrounding sounds, but it was still able to recognize the particular cries for help of the plants.
On average, the human ear can hear sounds up to around 20kHz, while the sounds produced by plants are in the 40-80kHz region, far beyond our hearing. “The sounds made by plants can’t be heard by humans but can probably be heard by various animals, such as bats, mice and insects,” Hadany tells us. Though this has yet to be proven, it’s possible that these creatures use this information to choose which plants to eat.
A study led by Reda Hassanien of China Agriculural University in Beijing years ago, also proved that plants reacted to sound waves, with some plants greatly increasing their yield. While evidence shows that plants can react to sounds, there’s no evidence today that they can actually hear them.
1. What can we know from the six-year experiment?A.Plants of different types make the sound of the same frequeney. |
B.Plants produce more regular sound in certain stressful situations. |
C.Plants make sounds with a much lower frequency when stressed. |
D.Plants make the sound of the same frequeney whatever the situation. |
A.To record the sounds. | B.To control the sounds. |
C.To produce the sounds. | D.To identify the sounds. |
A.Plants can hear each other’s cry for help. |
B.Animals can hear the sounds made by plants. |
C.Plants can make sounds and respond to sound waves. |
D.Animals decide what to eat based on the sounds plants make. |
A.Sounds That We Can’t Hear |
B.Beautiful Songs from Plants |
C.Plants React to Different Types of Stress |
D.Plants Talk, Especially When Stressed |
【推荐3】The Bridegroom’s Oak, a 500-year-old tree just outside of Eutin, in Germany, has its own postal address and receives around 40 letters every day. They’re sent by love seekers from around the world, in the hope that someone will read them and write back.
With so many dating apps(约会软件) and services available nowadays, sending letters to a tree hardly sounds like the best way to find love. However, there’s something charming about sending a letter and allowing fate(命运) to work its magic, so the Bridegroom’s Oak remains popular even now.
In 1890, a local girl named Minna fell in love with a young chocolate maker named Wilhelm, but her father didn’t allow her to see the boy. Instead of giving up on each other, the two started exchanging love letters secretly, by leaving them in a knothole(节孔) of an oak tree. After about one year, Minna’s father found out about their continued relationship, but instead of punishing them, he gave them permission to marry. The two lovers got married on June 2,1891, under the oak tree that helped keep their romance(罗曼史) alive.
The couple’s story spread around Eutin, and soon, people from all over the world who are unable to find love started writing romantic letters and leaving them in the tree’s knothole. However, love seekers visiting the Bridegroom’s Oak need respect only one simple rule. They can check all the letters in its knothole, and take with them the one they wish to reply to, but they have to put the others back for other people to find.
So far the Bridegroom’s Oak has been responsible for at least 100 marriages and many other romantic relationships.
1. What’s the Bridegroom’s Oak popular for?A.Its long life. | B.Its rare species |
C.Its good position. | D.Its special function. |
A.The best way to find love a century ago. |
B.What sufferings the two lovers experienced. |
C.The love story behind the Bridegroom’s Oak. |
D.How the two lovers kept their romance alive. |
A.Reply to all the letters in its knothole. | B.Read each letter in its knothole. |
C.Put their name at the top of each letter. | D.Take as many letters away as they like. |
A.Writing to the Bridegroom’s Oak is helpful. |
B.Germany needs dating and services. |
C.Germans hold a firm belief in fate. |
D.Foreigners have little idea of the Bridegroom’s Oak. |