California’s trees are dying at an alarming rate. The U.S. Forest Service said an aerial survey revealed that since their last survey in May, 36 million additional trees had died while in the grip of persistent drought, bringing the total since 2010 to more than 102 million. The tree deaths have been concentrated in the southern and central Sierra Nevada, but experts warn of increasing deaths in forests all the way up to the Oregon border.

A clue as to who first farmed potatoes

Nobody knows precisely what the Pilgrims’ first Thanksgiving feast looked like. But there’s one modern favorite that would not have been found at the inaugural Plymouth celebration: mashed potatoes. That’s because potatoes are native to South America and had not yet made their way to North America. Where in South America potatoes first became domesticated, however, is still unknown. Recent genetic studies point to the Andean highlands in southern Peru and northwestern Bolivia as the crop’s birthplace, and a new study in the Proceedings of the National Academy of Sciences reports finding such direct evidence — microremains of what seems to be cultivated potatoes on ancient grinding tools from southern Peru. The remains go back as far as 3400 BC. The authors of the study looked for microscopic starch grains on stone tools recovered from an ancient, high-altitude site called Jiskairumoko, in the Titicaca Basin of southern Peru. These tools, they suspect, were used to break up the skins of potatoes.

A plan to stop the ‘koalapocalypse’

The population of wild koalas in the southeast portion of Australia’s Queensland state has plunged by 80 percent in less than two decades, but researchers are offering a simple plan to save them. They can sum it up in three words: daylight saving time. Changing the clocks would help stem the koalapocalypse by reducing fatal encounters between koalas and the motorists who drive through their ever-shrinking territory, the researchers say. According to their calculations, the number of koala deaths could fall by 8 percent on weekdays and 11 percent on weekends.

Warming alters Arctic food chain

The Arctic Ocean may seem remote and forbidding, but to birds, whales and other animals, it’s a top-notch dining destination. But the menu is changing. Confirming earlier research, scientists reported that global warming is altering the ecology of the Arctic Ocean on a huge scale. The annual production of algae, the base of the food web, increased an estimated 47 percent between 1997 and 2015, and the ocean is greening up much earlier each year. These changes are likely to have a profound impact for animals further up the food chain, such as birds, seals, polar bears and whales. These algae are grazed by krill and other invertebrates that in turn support bigger fish, mammals and birds. But scientists still don’t know enough about the biology of the Arctic Ocean to predict what the ecosystem will look like in decades to come.

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