By Elizabeth Pennisi
The biggest trees, standing tall through storms and harsh winters, may look invincible. But a series of recent studies analyzing the effects of lightning, drought, and invasive pests on forests indicates that for trees, size is not strength, and forest giants are disproportionately vulnerable.
"There's always been an underlying assumption that large trees are somewhat buffered from environmental stress," says Andrew Barton, a forest ecologist at the University of Maine in Farmington. This new work "suggests that this might not be true." And with all three stresses likely to grow, big trees could become a particularly weak point in beleaguered forests, says forest ecologist David Lindenmayer of Australian National University in Canberra, whose work has shown that the loss of large trees puts entire ecosystems at risk of collapsing. Large trees are also major storehouses of carbon—one estimate suggests they hold 50% of a forest's carbon—and their deaths release it into the atmosphere, which could exacerbate climate change.