In the past 30 years, the non-profit organization Friends of Trees planted trees along the streets of Portland, Oregon. Now, a new study shows that each tree planted was connected with significant reductions in non-accidental and cardiovascular (心血管的) mortality (死亡率).
Evidence pointing to a connection between exposure to nature and lower mortality is obvious. Between 1990 and 2019, Friends of Trees planted 49,246 street trees. The research team looked at the number of trees planted in a given area in the past 5, 10 or 15 years. They connected this information with mortality due to cardiovascular, respiratory (呼吸的) or non-accidental causes in that same area, using data from the Oregon Health Authority. The results showed that in neighborhoods in which more trees had been planted, mortality rates were lower. This connection was significant for cardiovascular and non-accidental mortality, particularly for males and people over the age of 65.
Furthermore, the connection got stronger as trees aged and grew: The reduction in mortality rate connected with trees planted 11 to 15 years before was double that observed with trees planted in the past 1 to 5 years. This means that older trees are connected with larger decreases in mortality, and that protecting existing grown trees may be particularly important for public health. This study doesn’t provide a direct opinion into how trees improve health. However, the result that larger trees have a greater health effect than smaller ones is telling, because larger trees are better at absorbing air pollution, moderating temperatures, and reducing noise.
“We observed the effect both in green and less green neighborhoods, which suggests that street tree planting benefits both,” said Geoffrey H. Donovan, first author of the study. “Be-sides, the benefits of tree planting greatly outweigh (大于) the cost. Our results provide an important evidence-base for clear measures (e. g. planting trees) to increase the lifetime of urban people.”
8. How long did it take Friends of Trees to plant 49,246 street trees?
A.5 years. | B.10 years. | C.15 years. | D.30 years. |
9. What do we know about the study from paragraph 3?
A.Women gain no benefit from trees. |
B.Tree planting can cure respiratory diseases. |
C.Older trees contribute more to public health. |
D.Newly planted trees can better improve public health. |
10. What does Donovan suggest doing?
A.Protecting trees in forests. | B.Planting more street trees. |
C.Joining Friends of Trees. | D.Getting more benefits from nature. |
11. How does the author mainly develop the topic of the text?
A.By listing numbers. | B.By stating results. |
C.By describing processes. | D.By raising questions. |