雅思阅读 35: Forests in the Sky（天空中的森林）

改编自 AIPH / CTBUH case study（2026年）。雅思阅读 Section 3 难度，约 1050 词。 素材来源：https://aiph.org/green-city-case-studies/milan-italy-bosco-verticale/

Reading Passage

A. Dense cities face an awkward arithmetic. Their populations demand fresh housing close to work, yet the land on which to plant trees and parks is almost gone, and the heat trapped by streets of concrete and glass grows more oppressive each summer. One provocative answer to that dilemma arrived in Milan in 2014, when two residential towers known as the Bosco Verticale — the Vertical Forest — opened to public view in the city's regenerated Isola district. Conceived by the architect Stefano Boeri, the buildings are not merely covered in ivy; their projecting balconies support a small woodland of shrubs and mature trees. A forest that would normally require roughly five hectares of flat ground has been compressed onto a building footprint of about a thousand square metres — effectively fifty times the land use of an ordinary park of equivalent vegetation. The idea is disarmingly simple: if horizontal parks no longer fit, grow them upward. Since its completion the project has become one of the most photographed and copied experiments in contemporary urban design, and the subject of a quieter debate about whether it genuinely works as an ecosystem or is, as critics claim, an expensive gesture.

B. The claimed benefits begin with the air itself. Milan is notorious for the smog that settles in its basin during winter, and the dense canopy traps fine dust and absorbs carbon dioxide while releasing oxygen, and the leaves and branches act as a buffer against the noise of the surrounding traffic. Equally important is the effect on temperature. Milan's August heat can be oppressive, and the foliage shades the façades beneath it from direct sun; evaporation from the leaves provides a natural cooling that one study linked to a reduction of around 7.5 per cent in a building's annual energy demand. Residents of a test apartment rented by the design team reported that, in the warmest months, they did not need to switch on air-conditioning at all — a striking result for a city where such systems normally run flat out. The towers thus illustrate an attractive proposition: the same greenery that purifies the air may also pay for itself in lower cooling bills, softening the urban heat-island effect that makes city centres several degrees warmer than the countryside around them.

C. What surprised even the designers was the wildlife. Ecologists from Milan's technical university had assumed a few hardy insects might settle among the planters; instead the towers became an unexpected island of habitat in a densely built city centre. Surveys recorded more than twenty species of birds nesting among the branches, including redstarts and kestrels, and within two years peregrine falcons — birds not previously known to breed in that district at all — had moved in and raised young on the ledges. Butterflies and bees joined them, and researchers eventually estimated that some 1,600 birds and insects now live on the two buildings, which together carry around twenty thousand plants, seven hundred of them trees. The plants were chosen deliberately from more than sixty varieties of trees and shrubs, matched to the sunlight and wind of each balcony, and to keep aphids and other pests in check without heavy spraying, the team released twelve hundred ladybirds across the planters — a biological control that has, by most accounts, worked.

D. Behind the romantic image lies a demanding piece of engineering. Trees on a high balcony sway in winds that would topple them on the ground, so species were selected for their tolerance of exposed, windy sites, and every trunk was anchored securely in a deep, reinforced container that also had to support the weight of a fully grown tree, its root ball and its damp soil. The saplings are not planted straight from the nursery either: most are raised in specialist gardens for three to five years before installation, partly so that root systems develop to match the balcony containers and so that any specimen unlikely to thrive at height is weeded out early. Irrigation is centralised and automated, with sensors monitoring moisture and light around the clock, and a specialist team of "flying gardeners" — arborists who climb and descend the façade on ropes — tends, prunes and inspects the canopy once a year. None of this is cheap. A vertical forest is, in effect, a garden that must be watered, pruned and inspected in the sky, and its running costs are far higher than those of an ordinary concrete tower, a fact that critics seize upon when they argue the money would be better spent on parks at ground level.

E. Whether the model scales is the open question. From Milan the idea spread rapidly: towers inspired by the Bosco Verticale have risen in Nanjing, Utrecht and Lausanne, and a dozen other cities have announced or built similar schemes, sometimes with comparable vegetation and sometimes with a modest sprinkling of trees for show. Yet its admirers are careful not to overstate the case. A pair of towers, however leafy, cannot on their own cleanse the air of a metropolis or compensate for sprawling development at its edges; the design works best as one ingredient among many, alongside ordinary ground-level parks, reduced car use and denser, shorter buildings rather than isolated green gestures flung up above a sprawling city. Its real legacy may be attitudinal rather than numerical. Before Milan, trees were something placed around a building, a cosmetic afterthought chosen from a limited palette of street varieties and planted in the surrounding square. After the Vertical Forest, they became something a building could be — a load-bearing part of the architecture, planned from the first drawing as living, breathing structure rather than decoration added at the end.

Questions 1-4

Choose the correct heading for paragraphs B, C, D and E from the list of headings below.

List of Headings i. The environmental and cooling benefits the canopy provides ii. Why trees on a high balcony need special engineering iii. An unexpected influx of wildlife to the towers iv. How the Milan towers were financed v. The spread — and the real limits — of the model vi. The history of ivy on European buildings vii. Why concrete skyscrapers are cheaper to build

1. Paragraph B: ____
2. Paragraph C: ____
3. Paragraph D: ____
4. Paragraph E: ____

Questions 5-8

Choose the correct letter, A, B, C or D.

5. What is the central idea behind the Bosco Verticale? A. To build the tallest skyscraper in Europe. B. To grow parkland vertically when horizontal space is scarce. C. To replace apartments with farmland. D. To house endangered animals in captivity.

6. What did a study estimate about the green façades? A. They increased energy use by 7.5 per cent. B. They reduced annual energy consumption by around 7.5 per cent. C. They had no measurable effect on energy. D. They doubled the building's cooling requirement.

7. Why were ladybirds released on the towers? A. To attract tourists. B. To pollinate the flowers. C. To control pests such as aphids. D. To feed the nesting birds.

8. Why are saplings grown in nurseries for years before installation? A. To make them grow taller than the building. B. To let their root systems develop to fit the containers. C. To prevent them from being stolen. D. Because the soil arrives late.

Questions 9-13

Do the following statements agree with the claims of the writer?

Write:

• TRUE if the statement agrees with the information
• FALSE if the statement contradicts the information
• NOT GIVEN if there is no information on this

9. The towers support vegetation equivalent to about five hectares of parkland.
10. Peregrine falcons had bred in the Isola district for centuries.
11. The maintenance of a vertical forest is more expensive than that of an ordinary tower.
12. Vertical forests alone are enough to cleanse the air of a large city.
13. All the apartments in the towers were sold within a month of opening.

Questions 14-15

Complete the summary below using NO MORE THAN TWO WORDS from the passage.

Trees on exposed high balconies sway in strong (14) __________, so tolerant species were chosen and each trunk was anchored. The canopy is tended once a year by specialist "flying (15) __________".

答案与解析

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