From lettuces (生菜) farmed on New York’s skyline to thick corridors of trees occupying Colombian roadsides, green initiatives are running wild in cities around the world.

Replanting initiatives have sprung up since the start of the 21st century as urban development goals have shifted and alarm about global warming has grown.

In nine cities around the world, thanks to planting schemes on walls and roofs, the temperature can be reduced by 3.6 to 11.3 degrees Celsius (摄氏的) at the hottest time of day, according to a report by the French Agency for Ecological Transition. Green spaces have also been shown to improve health and well-being, including by reducing stress, anxiety and depression, improving attention and focus, bettering physical health, said Stephanie Merchant of Bath University’s department for health. “However, it’s about where they are created in relation to the needs of the local communities,” she added.

So, are all urban replanting projects worthwhile?

“For a scheme to be seen as effective, it must fulfill as many functions as possible,” said the economist and urban planner Jean Haentjens. In addition to lowering the temperature, he said it should also preserve biodiversity, improve well-being, raise awareness, be appealing to residents and suitable for its social context.

The Brooklyn Grange rooftop farm in New York grows more than 45 tonnes of organic produce a year. Covering three rooftops, totalling more than 22,000 square metres, the farm cultivates a wide variety of vegetables. But it has to limit the soil depth to about 30 centimeters and irrigate (灌溉) the soil a little more frequently, because it dries out very quickly. Another question is whether pesticides (杀虫剂), which scare off birds and insects, are used when the aim is to boost biodiversity. For Jean Haentjen, it represents “an interesting route”, depending on the context. “But we can’t make it the model of tomorrow,” he said.

THE WORLD’S RAREST LEOPARD

THESE BIG CATS GET A NEW CHANCE AT SURVIVAL.

Slowly stalking down the snowy hillside, the Amur leopard watches its prey through the trees. In the clearing below, a sika deer munches on tree bark, one of its few remaining food sources during the cold Russian winter. The leopard crouches, its body so low to the ground that its belly fur brushes the snow. Suddenly it bounds and springs forward, tackling the deer from 10 feet away. With a deadly combination of speed, strength, and stealth, the Amur leopard seems like it has everything it needs for survival. But not long ago — after decades of habitat loss and poaching — these endangered cats almost went extinct. Thanks in part to a newly established national park, however, Amur leopards are clawing their way back from the brink.

Disappearing Act

Most people think of leopards prowling African savannas, but the spotted predators are found in many different countries and habitats. They’ve adjusted to life in grasslands, jungles, deserts, and freezing, hilly landscapes. It’s there — along the Russian-Chinese border — that Amur leopards live, adapting to their chilly climate with bushier fur and longer legs to trudge through the deep snow.

Although Amur leopards thrive in freezing temperatures, by the late 20th century the human population moving into their habitat shrunk their California-size range by a huge 98 percent, trapping the animals in a stretch of land less than half the size of Puerto Rico. Poachers roamed the space that remained, killing the cats to sell their coats. In 2000, conservationists were stunned when a new count of Amur leopards estimated that only 30 were left in the world (though it was based on a study done by counting tracks, which isn’t the most reliable method). “These animals were going extinct,” biologist Dale Miquelle says. “Some of us were afraid it was too late to save them.”

Their solution? A new national park dedicated to protecting the endangered cat. But first, scientists had to convince the government that this was something worth doing — and that it could be done.

Domestic animals have often been known to save their human companions from danger. From the quick thinking of Duke, the dog who warned his guardians of their baby’s need for medical attention, to the smart actions of service dog Yolanda, who rescued her highly near-sighted human from a house fire by dialing 911, there are many animals out there who have earned the lasting gratitude of their human friends. However, it is truly surprising to hear about undomesticated(未驯服的) animals who, without any obvious reason, stepped in and saved humans from the coming death.

In June 2005, a twelve-year-old girl was caught by four men in rural south-west Ethiopia as she made her way home from school. A week after the kidnapping, her captors were trying to move her, when three lions chased the men off. The lions remained with the terrified girl until police officers arrived to send her to safety. She told them that although she had been beaten by her kidnappers, who it is believed had been attempting to sell her into a forced marriage, the lions had not touched her.

Sergeant Wondmu Wedaj said, “They stood guard until we found her and then they just left her like a gift and went back into the forest. Everyone thinks this is some kind of miracle, because normally the lions would attack people.” An Ethiopian wildlife expert claimed that the lions may have spared the girl because her cries had sounded like the mewing of a cub(幼兽).

This unbelievable story shows that, contrary to certain popular knowledge of wild animals as threats who must be removed to make way for human advancement, we have much more in common with non-human animals and are a lot more dependent on them than we realize. They, too, are capable of showing pity. They, too, have been known to step in and save those weaker than themselves at the most unexpected times, and in ways that humans often fail to predict. They, too, deserve to live out their lives on their own terms.