【推荐1】California has lost half its big trees since the 1930s, according to a study to be published Tuesday and climate change seems to be a major factor (因素).

The number of trees larger than two feet across has declined by 50 percent on more than 46, 000 square miles of California forests, the new study finds. No area was spared or unaffected, from the foggy northern coast to the Sierra Nevada Mountains to the San Gabriels above Los Angeles. In the Sierra high country, the number of big trees has fallen by more than 55 percent; in parts of southern California the decline was nearly 75 percent.

Many factors contributed to the decline, said Patrick McIntyre, an ecologist who was the lead author of the study. Woodcutters targeted big trees. Housing development pushed into the woods. Aggressive wildfire control has left California forests crowded with small trees that compete with big trees for resources (资源).

But in comparing a study of California forests done in the 1920s and 1930s with another one between 2001 and 2010, McIntyre and his colleagues documented a widespread death of big trees that was evident even in wildlands protected from woodcutting or development.

The loss of big trees was greatest in areas where trees had suffered the greatest water shortage. The researchers figured out water stress with a computer model that calculated how much water trees were getting in comparison with how much they needed, taking into account such things as rainfall, air temperature, dampness of soil, and the timing of snowmelt (融雪).

Since the 1930s, McIntyre said, the biggest factors driving up water stress in the state have been rising temperatures, which cause trees to lose more water to the air, and earlier snowmelt, which reduces the water supply available to trees during the dry season.

【推荐2】Young Chinese are increasingly making their voices heard and influencing world opinion as they take on more important roles in international organizations and global projects. At a ceremony in Beijing, singer and actor Karry Wang was made the National Goodwill Ambassador for the United Nations Environment Programme (UNEP) by Erik Solheim, the organization’s executive director.

“The youth are no longer merely onlookers when it comes to environmental action, nor should they be. I will spare no effort to do everything I can to take care of our Earth, and I invite everyone to join me in generating a wave of positive action,” Wang said in his speech after the appointment. In 2016, Wang widely publicized the Wild for Life campaign, reaching 400 million viewers.

Beyond drawing attention to wildlife, he called on his followers to pledge to reduce their electronic waste through social media. Within 24 hours, his post was shared 1.67 million times and more than 400,000 followers signed the pledge. “Our actions will soon be the leverage to change the world.” Wang says, calling on the younger generation in China and around the world to raise their awareness of environmental issues.

Erik Solheim says, “It is inspiring to see the strong and determined voice of Chinese youth when it comes to the environment. When young people set their minds to change, it is incredible to see the great things that can be accomplished. We are very excited to work with Karry Wang to create even more awareness about the environmental problems and solutions.”

According to a UN report, young people’s participation will help achieve the sustainable development goals in the Asia-Pacific region set for 2030. Besides Wang, other UNEP Goodwill Ambassadors include actress Li Bingbing, Ellie Goulding and celebrities from all walks of life both from China and abroad.

【推荐2】Born with severe hearing loss, Li has found her way to communicate with the world—through painting.

Before learning to paint, Li always felt lonely in a silent world. She knew she was different from her peers because she could not hear. But a painting class in primary school opened for her a door to creativity and a way of expression.

“I still remember my first mural, which was to help a kindergarten to design and paint its wall,” Li says. “The project made me realize how happy I was immersing myself into painting.”

To pursue her passion for art, Li went to study advertising design at a vocational and technical school. “Painting brushes can help me create a colorful world in my imagination, telling my thoughts on paper, instead of through voices,” Li said.

Graduating from college in 2005, Li got a job as a typist at a public institute. But she could not communicate well with her other colleagues. Her husband understood how she felt because he lost his hearing due to medication when he was 1 year old. He is also an art lover. In March 2016, under her husband’s suggestion, Li quit her job and joined her husband’s company, which specializes in 3D wall and ground paintings.

Wall painting is a demanding job because it requires people to work outdoors, whether in extremely cold or hot weather. As all the people are hearing-impaired in their company, communication with clients is the most common challenge that the team faces.

Now in many parks and scenic spots, the couple have created large-scale murals and interactive pavement painting that make onlookers a part of the drawings.

“My husband and I want to introduce painting to more people like us and help them find their own way to make a living,” Li says. Now Li has an apprentice who just graduated from college. While coaching the newcomer, Li is exploring her own style and hopes to become an illustrator and open her own exhibition one day.

“They’re energetic young people with a passion to create new things, and you can feel that in their paintings,” one of their clients said. “They’re also a professional, dedicated team, often working late into the night on the designs for us.”

Li hopes that their stories can encourage more hearing-impaired people to build their own careers and achieve their goals, regardless of how tough it may be.

To help people with hearing loss, what does Li intend to do?

【推荐1】Many people would answer the question of what makes us human by insisting that we are cultural beings. There is no doubt that we are. But one definition of culture is the totality of traditions acquired in a community by social learning from other individuals, and many animal species have traditions. Can we then say that some animals are cultural beings too?

One approach to study culture in animals is the so-called Method of Exclusion (排除), in which scientists investigate behavioral variations across populations of one species. In a famous study, scientists learned that chimpanzee (黑猩猩) behaviors were socially passed on as they were present at some sites but not at others, despite having same ecological settings. For example, chimpanzees in Tai National Park in Ivory Coast are well-known for their nut-cracking skills. Chimpanzees in Gombe national part in Tanzania, on the other hand, do not crack nuts, although nuts exist in their environment too.

However, when applying the Method of Exclusion, one has to be very careful. There are other factors that could also explain the pattern of behavioral evaluation. For example, some of the chimpanzee techniques scientists evaluated occur in only one of the three subspecies. So it’s quite possible that these behaviors also have an innate component. This would mean that one chimpanzee subspecies uses a new technique not out of cultural tradition, but because the behavior is fixed to specific genes. Another factor that has to be excluded is of course the environment Chimpanzees in Mahale do not fish algae (水藻), simply because algae does not exist there.

But when we exclude all the variations that can be explained by genes or environment, we still find that animals do show cultural variations. Does that mean there is no real difference between them and us after all? Not exactly: There is a fundamental difference between human and animal culture. Only humans can build culturally on what generations before us have learned. This is called “cumulative culture”. We don’t have to keep reinventing the wheel. This is called the “ratchet (棘轮) effect”. Like a ratchet that can be turned forward but not back, people’s cultural techniques evolve.

It is likely that behaviors we see today in chimpanzee cultures could be invented over and over again by individual animals themselves. In contrast, a child born today would not be able to invent a computer without the knowledge of many past generations.