【推荐2】If you’re looking for a reason to care about tree loss, this summer’s record-breaking heat waves might be it. Trees can lower summer daytime temperatures by as much as 10 degrees Fahrenheit, according to a recent study. But tree cover in US cities is shrinking (缩减). A study published last year by the US Forest Service found that we lost 36 million trees annually from urban and rural communities over a five-year period. “If we continue on this path, cities will become warmer, more polluted and generally unhealthier for inhabitants,” said David Nowak, a senior US Forest Service scientist and co-author of the study. Nowak says there are many reasons why our tree cover is declining, including hurricanes, tornadoes, fires, insects and disease. But the one reason for tree loss that humans can control is sensible development.

Nowak says there is a downside to trees too, such as pollen allergy (花粉过敏) or large tailing branches in storms, and people don’t like sweeping leaves. But, he says, there are ways cities and counties can manage trees to help communities thrive (繁荣). Urban forests especially need our help to replace fallen trees. Unlike rural areas, it is very difficult for trees to repopulate themselves in a city environment with so much pavement and asphalt (沥青). “A lot of our native trees can’t actually find a place to drop a seed so they can regenerate,” explains Greg Levine, co-executive director of Trees Atlanta. “That’s why the community has to go in and actually plant a tree because the areas just aren’t natural anymore.”

Nowak says the first step is caring for the trees on your own property (财产). “We think we pay for our house, and so we must maintain it. But because we don’t pay for nature, we don’t need to. And that’s not necessarily true.”

【推荐3】From red apples and yellow lemons to blueberries and green melons, fruit comes in many different colors.     1    

According to scientists, fruit colors actually come from their different pigments, such as red or yellow carotenoid and blue or purple anthocyanin. These pigments appear in different amounts, depending on the fruit’s environment. This causes the fruit to turn a certain color.

    2     They found that red fruit tends to grow in cooler places. Instead of just growing in one place, you can find them growing in many places around the world. Blue and purple fruit mostly grows in warm places.     3     The scientists also found that the closer the fruit is to the equator,the darker its color will be.

    4     Animals eat fruit and drop the seeds in other places later. This helps the fruit spread and grow in different places. However, animals see colors in a different way. Therefore, in order to attract animals, some fruit develops colors that are easy for animals to see. For example, birds can see red more easily than humans can.     5     The lemurs of Madagascar are red-green color blind. Many yellow fruit can be found in their habitats, as they can easily see this color.

【推荐2】Pesticides might just be a bee's. worst enemy. They harm their brains, stow down their re-production, and even kill their buzz. Now it seems they damage their social lives and reduce their ability to care for their young.

While previous studies have shown that commonly used neonicotinoid pesticides make bees sick and affect how they search for food and navigate, a new study gives more of an idea of how these chemicals affect the internal workings of a colony. Studying these effects has proved difficult, so the team employed a new technique. They stuck tiny QR codes to the backs of bumble-bees and tracked their movements using a robotic camera.

The researchers looked at 12 colonies housed in a lab, giving some the same level of imidacloprid-the world's most commonly used pesticide-that they'd be exposed to in the wild while keeping others pesticide free as controls. They checked on them for a few minutes 12 times a day. The findings are published in the journal Science.

Unfortunately, the researchers found a number of obvious differences between the bees exposed to the pesticide and the controls. The bees given neonicotinoids spent less time interacting with other bees and more time resting. This lull (间歇) in activity tended to happen more at night, but the researchers aren't sure why.

“Bees actually have a very strong circadian rhythm (生理节奏),”lead author James Crall explained in a statement. “So what we found was that, during the day, there was no statistically observable effect, but at night, we could see that they were crashing. We don't know yet whether the pesticides are destroying circadian gene regulation or if this is just some, maybe physiological feedback..But it suggests that, just from a practical perspective, if we want to understand or study these compounds, looking at effects overnight matters a lot."

【推荐3】A BioBlitz is an event that focuses on finding and identifying as many species(物种) as possible in a given area over a short period of time. A BioBlitz is also known as a biological inventory(清单). The main goal of a BioBlitz is to get an overall(全面的) list of the plants, animals, and other species that live in a place.

A BioBlitz has its own features different from a scientific inventory. Scientific inventories are usually limited to biologists, geographers, and other scientists. A BioBlitz brings together volunteer scientists, as well as families, students, teachers, and other members of the community. While a scientific survey often focuses on faraway or isolated areas, BioBlitzes involves places that are connected to a living or industrial areas. Finally, scientific surveys may take a long period of time to conduct. A BioBlitz lasts a short period of time, traditionally 24 hours.

These differences make a BioBlitz a unique biological survey that encourages a relationship between the nature and human communities of a certain area. Citizens work together with scientists to learn about the biological diversity of local natural spaces. In the process, they gain skills and knowledge and develop a stronger connection to their home environment. A BioBlitz makes citizens better understand and protect local natural spaces.

Hundreds of BioBlitzes have been conducted all over the world, mainly in the United States. Canada, Australia, and Europe. The first BioBlitz was sponsored by the National Park Service and the National Biological Service in Washington D.C.’s Kenilworth Park and Aquatic Gardens in 1996. Surrounded by heavy living and industrial development, Kenilworth Park was thought to have very little biological diversity. Scientists, however, recorded more than 900 species that first year and added even more species to their list at continuous Kenilworth BioBlitzes.