These oak trees in western Germany are approximately 1,000 years old. Old trees like these are dying at much faster rates than young trees, a new study finds.
California’s giant sequoias can live for more than 3,000 years, their trunks stretching two car lengths in diameter, their branches reaching nearly 300 feet toward the clouds. But a few years ago, amid a record drought, scientists noticed something odd. A few of these arboreal behemoths inside Sequoia and Kings Canyon National Parks were dying in ways no one had ever documented—from the top down.
When researchers climbed into the canopies, they discovered that cedar bark beetles had bored into a few branches. By 2019, at least 38 of the trees had died—not a large number, but "concerning because we’ve never observed this before,” says Christy Brigham, the park’s chief of resource management.
Beetles have ravaged hundreds of millions of pines across North America. But scientists had assumed that stately sequoias, with their bug-repelling tannins, were immune to such dangerous pests. Worried experts are investigating whether some mix of increased drought and wildfire, both worsened by climate change, have now made even sequoias susceptible to deadly insect invasions.
If so, these ancient sentinels would be just the latest example of a trend experts are documenting around the world: Trees in forests are dying at increasingly high rates—especially the bigger, older trees. According to a study appearing today in the journal Science, the death rate is making forests younger, threatening biodiversity, eliminating important plant and animal habitat, and reducing forests’ ability to store excess carbon dioxide generated by our consumption of fossil fuels.
“We’re seeing it almost everywhere we look,” says...