1 . Las Vegas city in Nevada is built in a desert. The city may be known to the world for its partying. But officials have found that there are 21 square kilometers of useless grass. The grass is never laid on, played on or even stepped on. The grass is only there to look nice.

Now, the city is asking the Nevada state legislature (立法机构) to ban useless grass. It is trying to become the first place in America to ban that kind of grass often seen between streets, in housing developments and in office parks.

Useless grass nearly makes up 40% of all the grass in Las Vegas and it needs lots of water to survive. Grass needs four times more water than dry climate plants. By tearing out the grass, the city could reduce yearly water usage by 15%.

In 2003, the Southern Nevada Water Authority banned developers from planting grass in front of new homes. It also offered homeowners $30 for each square meter of grass they tear out. But fewer people are now using the program. Water usage has increased here by 9% since 2019. And last year, Las Vegas set a record of 240 days without major rainfall. The Colorado River provides much of Nevada’s drinking water. The river could lose more water as climate change affects it.

Water officials in other dry cities said water usage needs to be reduced. But they fear the reaction to reforms like the ones in Las Vegas if their communities do not accept them. Cynthia Campbell is the water resources adviser for the city of Phoenix in Arizona. “The city restrictions (限制) may get too hard for some residents (居民). They’ll say that is the point of no return for them,” Campbell said. “For some people, it’s a pool. For some people, it’s grass.”

4 . A simple and common way to water plants is to hold a garden pipe (管子) and let the water fall down directly on the plants and soil. This is a good choice that does not waste water. It also can help prevent plant disease. But a garden pipe is not the only way to water your plants.

The When and How of Watering

    1     This lets the water go deeply into the soil before the weather gets too hot. If you water late in the day, the water will just evaporate (蒸发) from the surface. If you water in the evening, the plants stay too wet overnight.

How you water is just as important as when you water. If you water quickly every day, it does not help the roots, which can spread over 30 centimeters into the soil. Water the soil less often, but deeply. Be careful when watering very dry soil because the water will just run off without getting into the soil.     2    

Collect and Reuse Water

One way to help keep costs low for watering is to use used water. Instead of emptying water out after boiling foods, keep it and reuse it to water plants.     3     You can also catch and use rainwater.

Choose Native Plants

Most gardeners just think about which plants look good and the plants’ sunlight needs.     4     Drought-resistant (抗旱的) plants should not be overwatered when trying to keep thirstier plants watered.

It is also best to use plants that are native (当地的) to the area where you live. These plants are likely to be resistant to drought.     5     After that, they can live on just rainwater except for during times of extreme heat.

8 . Rainforests provide much of the world’s oxygen. People have been trying to protect them for years. But another type of forest, the cloud forest, is just as important to humans.

These forests are at the tops of mountains, generally near the equator (赤道). These wet, wooded mountaintops are mainly in African and Central and South American countries. They are called “cloud forests” because their height allows for the formation of clouds among the trees. The trees in these forests pull water out of the clouds. The water gathers on the leaves and falls into small rivers below, which flow into towns at the bottom of the mountain. The yearly rainfall in these areas is about 180 centimetres. Cloud forests can pull in up to 60 percent of that. The water is important to the plants and the people in the area. It helps them survive.

Cloud forests are also home to countless species of plants that can’t be found anywhere else. One small cloud forest has as many types of plants as there are in all of Europe. In fact, there are so many that scientists haven’t made a complete list of them yet.

These forests are being destroyed at an increasing speed. Trees are being cut down, and roads are being built in their place. Some people have a goal to get government money to protect the forests. But they have had little success so far. Another way is to take the place of the destroyed plants with new ones. That, too, has been difficult because the plants are so special. There’s plenty of work to be done, but saving the cloud forests is still possible with creative solutions.

9 . Trees don’t look at the calendar to see when spring arrives, but they seem to know when spring is here better than we do. The annual shift from winter to spring is a breathtaking event to watch as leaves become green and a lush(苍翠的) environment reveals itself. Recently a research takes a look at why trees in cities are turning green earlier than expected.

Scientists use satellite imagery to see when plants turn green. By comparing spring green ups in the 85 largest US cities, scientists found that on average trees start to turn green nine days earlier in cities due to the combined effect of artificial lights and urban heat effect.

According to the findings, one of the reasons is the artificial light. City lights brightening the night skies, billboard signs lit up on roadways and car headlights all contribute to shifting the regular day to night cycle that plants and trees rely on. In order to stay alive during cruel winters, trees hit the pause button on their growth. Since temperatures can vary dramatically throughout the winter, the length of daylight is the signal trees look for to safely start growing again and turn green.

On average cities are typically 1.8 to 5.4F warmer than rural areas. This is known as the urban heat island effect. The changes in city environments may affect seasonal changes even more than climate warming and mosquito season, water cycles, and also affect pollinators(授粉媒介).

Despite the worries and concern, it isn’t all bad news. “With a longer growing season, trees would be able to absorb more carbon dioxide,” A researcher said. “Hopefully they’d have a longer period to do the cooling effect that can help relieve the urban heating effect in cities.”

10 . A new report by a British plant protection group says that almost 30 percent of the world’s tree species (物种) are at risk of dying out. The State of the World’s Trees report shows that 17,500 tree species are at risk of extinction. And 440 species have fewer than 50 trees left in the wild. The report was recently published by Botanic Gardens Conservation International (BGCI).

In a statement, BGCI Secretary General Paul Smith said, “This report is a wake-up call to everyone around the world that trees need help.”

Trees help support the natural environment and are considered important for fighting the world’s warming and climate (气候) change. The extinction of a single tree species could mean losing many others. “Every tree species is important to millions of other species that depend on trees all over the world,” Smith said.

The report shows that thousands of kinds of trees in the world’s top six countries for tree-species diversity (多样性) are at risk of dying out. The greatest single number is in Brazil, where 1,788 species are at risk. The other five countries are Indonesia, Malaysia, China, Colombia and Venezuela.

Now tree species are facing many challenges. The most worrying thing is that climate change and terrible weather are growing dangers. The report adds that at least 180 tree species are in danger because of rising seas and terrible weather. It points out that island tree species are more at risk than other trees because many islands have species of trees that can be found nowhere else. .