But nutrient withdrawal takes time, and the process leaves the leaves vulnerable to damage from sunlight.
Anthocyanins protect leaves by "shading" them from excessive sunlight during the plant's relatively vulnerable autumn season, Hoch explained.
In a study of plants that had been genetically modified not to be produce anthocyanins, Hoch found that the modified plants were unable to send as many nutrients to their roots for winter storage.
"So the bottom line is that the plants that were able to produce red pigments were able to squeeze more of the nutrients out of their leaves than the ones that couldn't," he said.
Thus, Hoch says, plants living in nutrient-poor soils benefit more from anthocyanin than those living on better soils.
Scientists only recently made these connections, Habnick said, because when most other leaf-peepers are taking their fall-color tours, biologists are busy with academics.
"Most people's field season is in the summer," she said.
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