On a hot summer afternoon, a street shaded by trees can feel very different from one lined with bare walls and dark pavement. The difference is not simply a matter of appearance. Trees block some sunlight before it reaches the ground, and water released from their leaves can cool the surrounding air. For this reason, planting trees is often presented as a straightforward way to reduce urban heat.
Yet the benefits of urban trees depend on where they are planted and how they are cared for. A row of young trees may offer little shade for years, while mature trees can be damaged by construction or prolonged drought. In some neighborhoods, limited space, underground pipes and narrow sidewalks make planting difficult. Cities that announce ambitious planting targets without planning for maintenance may end up with many dead saplings and few lasting improvements.
Researchers also point out that tree cover is often distributed unevenly. Wealthier districts may have leafy streets and parks, whereas areas with fewer resources can have more paved surfaces and less shade. This difference matters because people who work outdoors, live in poorly insulated homes or have limited access to air-conditioning face greater risks during heat waves. A citywide average can hide the fact that certain residents experience much more dangerous temperatures than others.
That does not mean trees are an ineffective response. It means they should be part of a broader plan. Cities can combine tree planting with reflective roofs, shaded bus stops, drinking-water stations and public cooling centers. They can also involve residents in choosing planting locations and caring for young trees. When local needs guide the work, trees are more likely to survive and shade is more likely to reach people who need it most.
Ultimately, the success of an urban greening project should not be measured only by the number of trees planted. It should also be judged by whether the trees survive, whether they lower temperatures in vulnerable neighborhoods and whether residents can use the shaded spaces. A smaller project that is carefully maintained may do more for public health than a much larger planting campaign that exists mainly on paper.
五路阅读理解题
What is the main idea of the first paragraph?
A. Trees can make streets cooler by providing shade and releasing water.
B. Dark pavement is the only cause of high city temperatures.
C. Trees mainly improve the appearance of urban streets.
D. Summer afternoons are cooler in cities than in the countryside.
Why might a city’s tree-planting plan fail to bring lasting benefits?
A. Residents usually refuse to walk under mature trees.
B. Young trees need time and proper care, and some planting sites are difficult to use.
C. Trees cannot grow near sidewalks or underground pipes.
D. Construction projects always increase the amount of shade.
What does the third paragraph suggest about the distribution of tree cover?
A. It is generally equal across neighborhoods.
B. It is concentrated in areas with the highest temperatures.
C. It may reflect differences in neighborhood resources and residents’ exposure to heat.
D. It has little effect on people who work outdoors.
According to the passage, what should cities do as part of a broader heat-response plan?
A. Replace all public parks with cooling centers.
B. Plant trees without consulting local residents.
C. Combine trees with measures such as reflective roofs and shaded bus stops.
D. Focus exclusively on neighborhoods that already have many trees.
How should the success of an urban greening project be evaluated?
A. By the number of planting announcements made each year.
B. By how many trees are planted, regardless of whether they survive.
C. By whether trees survive and benefit residents who need shade.
D. By whether the project covers the largest possible area.
