1 . Between 20 and 40 per cent of planet Earth is covered in grasslands, across every continent except for Antarctica. Grass is a low-growing, flowering plant with groups of narrow leaves growing from its base. Strong roots typically hold this plant’s leaves firmly to the ground.
One of the most common sights along stretches of grass is grass-eating animals. This is because many large animals rely on extensive grasslands to survive, and grass grows well with this regular trimming (修剪). The plants gain their energy from sunlight and require healthy cells to do so. If the leaves aren’t cut, the tips die and start to rot. When they are damaged with a clean cut, however, the cells are caused to grow quicker and produce new, healthy tissue. This is also why cutting your garden’s grassland regularly can make your grass look thicker and healthier.
Humans rely on grass for food, too. Many grasses, such as w heat or corn, are harvested as a main part of some diets. Meanwhile, grass is used indirectly to produce food in the form of livestock (牲畜). Cattle farmers require grass in their fields to feed cows and sheep before they are turned into meat for human consumption.
One of the most debated questions is how long ago grass evolved. Because grass doesn’t preserve well as a fossil, a definitive answer is hard to come by. Until recently, many scientists estimated that grass began to grow on Earth between 50 and 65 million years ago.
However, within the last decade, a piece of 100-million-year-old amber (琥珀) was found that appeared to contain the oldest grass fossil to date. Studies of fossilized dinosaur faces (粪便) also suggest that some dinosaurs lived at the same time that grass grew on the planet, incorporating it into their diets.
1. What is the function of the roots mentioned in Paragraph 1?| A．To fix the leaves to the soil. | B．To store water and nutrients. |
| C．To support the growth of the plant. | D．To protect the plant from animals. |
| A．By improving soil quality. | B．By encouraging cell growth. |
| C．By preventing the tips from dying. | D．By attracting more animals to eat them. |
| A．Grass doesn’t preserve well as a fossil. | B．There are no fossils of grass available. |
| C．There is no solid evidence of its evolution. | D．Scientists can’t agree on its origin. |
| A．The Variety of Grass | B．The Development of Grass |
| C．How Grass Change Life | D．How to Make Grass Grow Well |
2 . Tree-planting, intended to help draw down carbon dioxide from the atmosphere, has become a synonym (同义词) for climate action. In our constant focus on trees, we’ve developed a fixed understanding: Trees absorb carbon dioxide, end of story. The reality is that trees don’t grow well alone. They exist within complex communities, helped along by each other as well as the animals they coexist with. The woodland isn’t nature’s only carbon sink: Grasslands and oceans also help reduce the carbon level and rely on a healthy amount of biodiversity.
That’s what the paper, published in Nature, wants to get across. Co-author Oswald J. Schmitz, a professor of ecology at Yale University, said trees might not be able to do their carbon-uptake job efficiently without the right animals in their ecosystem. That’s because animals animate the carbon cycle through their behavior and roles in the ecosystem. He added that the very presence of wild animals could cause feedback effects that change the ecosystem’s capacity to absorb, release, or transport carbon.
In Serengeti, for instance, the sharp decline in wildebeest (角马) population s during the mid-20th century allowed grass to grow wildly, eventually promoting wildfires that consumed 80 percent of the ecosystem annually and led to a net release of carbon dioxide into the atmosphere. When disease management and bans on illegal hunting helped animal populations recover, a greater share of the carbon stored in plants was consumed by wildebeest and released as waste, keeping it in the system and restoring the grassland as a carbon sink.
Researchers rarely consider wildlife conservation as a strategy to increase an ecosystem’s carbon storage capacity, said Schmitz. “They think that animals either aren’t important enough or that you can’t take up carbon and conserve animals at the same time,” he said. “Our message is that you can and should. It can be a win-win for both biodiversity conservation and carbon uptake.” We need a full picture-with both trees and animals-to explore nature’s full potential.
1. What can we learn from the first paragraph?| A．Actions are needed to reduce carbon dioxide. | B．Trees are a quick solution to the climate crisis. |
| C．People are not thinking through trees properly. | D．Grasslands and oceans help maintain biodiversity. |
| A．Activate. | B．Restart. | C．Disturb. | D．Break. |
| A．The conservation of animals is still a serious issue. |
| B．Animals can swing the ecosystem’s capacity to store carbon. |
| C．Human impacts bring about the reduction in wildlife populations. |
| D．The increase in animal species causes a decrease in carbon uptake. |
| A．Animals Adjust Themselves to Climate Change |
| B．Woodland Isn’t the Only Carbon Sink on the Earth |
| C．The Serengeti Ecosystem Needs Urgent Improvement |
| D．Trees May Fail to Fulfil Their Duties without Animals |
Watering is key to growing plants well, so here we look at how to get it just right. This not only means providing the water our gardens need but using it wisely. Water is a precious resource and supplies in the UK are under pressure from the effects of climate change, population increase and the need to protect the environment. Generally, several aspects need to be considered.
When to water
Water in the mornings, if you can, as this is when the sun comes up and plants start to transpire (蒸腾) in sunlight, drawing water from the soil, through their roots, up their stems and to their leaves. Evening watering is also fine, as the cooler conditions mean less water is lost to evaporation (蒸发). Watering in the heat of the day is not a good idea, as much water is lost through evaporation from the surface of the soil. Plants will use water more efficiently if watered in the cooler parts of the day.
How to water
Watering thoroughly matters. It helps get the water down to the deeper root tips where it’s needed. But, equally important, the soil doesn’t have to be really wet all the time because plants roots need air as well as water to grow well. Otherwise, there might be no flower or fruit, and even a worse result might come along.
Other tips
To use water in the most economical way, it’s good to learn different plants’ watering requirements. For example, a container plant in hot sunny weather may need watering daily, whereas a mature shrub might only need a drink in extreme drought. Annual flowers and vegetables produced in the spring are likely to need more watering than self-sown or autumn grown plants as they have new and shallow root systems. So, don’t treat all the plants in the same way.
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4 . Covered in lush fur, the thickest in the animal kingdom, sea otters (海獭) can live their entire lives in the ocean, feeding heavily upon seafloor animals such as shellfish. They are often seen to eat clams(蛤), which bury themselves in meadows of eelgrass (大叶藻场), a wide-ranging plant species growing in water. Eelgrass meadows where sea otters dig for clams become partly bare, which is commonly a concern for ecologists.
As it turns out, the meadows with otters are healthier, with more eelgrass, according to a new study published in Science. That's because by gently disturbing the seabed, the otters make the plants flower and produce seeds. What's more, their digging provides more space and sunlight for seeds to settle and grow. The enhanced genetic diversity caused by sea otters could make eelgrass more adaptable to present and future threats.
The finding is a powerful example of how animals such as otters influence their ecosystems beyond predation (捕食), often in unseen and little-known ways, says study leader Erin Foster, a research associate at the Hakai Institute. It also means sea otters, an endangered species, are vital to their environments and give eelgrass, which is in danger worldwide, a better chance at staying healthy and surviving.
Seagrass habitats are also important for many fish, providing food for animals, absorbing, and filtering harmful pollution and bacteria from the water. "Genetic diversity typically strengthens the adaptability of species, and considering the challenges we're facing…this will be important for eelgrass meadows, and from this aspect, the impact the otters are having deserves our lasting concern," says Foster.
1. What do we know about sea otters?| A．They live part of their lives underwater. | B．They mainly feed on sea animals like fish. |
| C．They eat clams beneath eelgrass meadows. | D．They become a new concern for ecologists. |
| A．By giving opinions. | B．By presenting reasons. |
| C．By clarifying concepts. | D．By comparing results. |
| A．To provide examples of sea otters' predation. |
| B．To show the urgency to protect the environment. |
| C．To highlight the role of otters in their ecosystems. |
| D．To warn against the potential risk of climate change. |
| A．Overestimated. | B．Noteworthy. | C．Temporary. | D．Unpredictable. |
